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DIFFERENTIAL RESPONDING TO THE INTERNAL AND EXTERNAL FACIAL FEATURES:

HOLISTIC AND PART-BASED PROCESSING

Margaret C. McKinnon

A thesis submitted in conformity with the requirements for the degree of Masters of Arts

Graduate Department of Psychology University of Toronto

O Copyright by Margaret C. McKinnon, 1998.

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Margaret C. McKinnon Masters of Arts, 1998

Department of Psychology, University of Toronto

Abstract

We investigated earlier daims (e.g., Moscovitch et al., 1997) that recognition of

upright (same and different) and inverted faces relies upon holistic and part-based

decompositional processing strategies associated with the face- and object-

recognition systems, respectively. Viewers made a same-different judgment of two

faces presented either sequentially or simultaneously on screen. Whereas

responding to upright same faces appeared to rely upon holistic or configurational

processing strategies, responding to upright different and al1 inverted faces was

instead mediated by part-based processing strategies. Moreover, attending to the

intemal features alone was sufficient to form a discrimination judgment for upright

different and al1 inverted faces; the same was true for upright same faces when

attention was focused on the intemal features alone at study. By contrast, viewers

relied upon both the interna1 and external features to form a discrimination judgment

for upright same faces when attention was focused on the entire face at study.

Acknowledgments

I would like to express my sincere appreciation to my supervisor, Morris

Moscovitch, for his many insightiul cornments and suggestions during the

preparation of this thesis. 1 am also indebted to Giampaolo Moraglia, my subsidiary

supervisor, for his valuable comments. In addition, Marilyne Ziegler provided

invaluable assistance in the computer programming of these experiments, as did

Elizabeth Olszewska in scheduling participants. I would also like to thank Jason

Gold and Filippo Speranza for their aid in preparing stimuli for an adjunct project

associated with this thesis and Sarah Khan for her assistance in running

participants and analyzing the current experiments.

I would also like to thank my fellow graduate students, Amy Siegenthaler,

Myra Fernandes, Tara Moroz, and Derryn Jewell for providing much appreciated

moral support throughout the year. I am also indebted to Glenn Schellenberg for the

early interest he took in rny career and for his continued encouragement. As always,

I also appreciate the support and encouragement provided by Julia Nelson and

Carlo Sullo. Finally, I thank my family, Matthew McKinnon and Ellen Trinh, and most

especially my parents, Barry and Susan McKinnon, for their love, support, and

guidance, not only in the period surrounding the preparation of this thesis, but

throughout.

Table of Contents

........................................................................................................ List of Tables vi ...................................................................................................... List of Figures vii

General Introduction ..................................................................................... 1

Expe riment 1 ....................................................................................................... M ethod ...................................................................................................... . . .................................................................................... Participants

...................................................................................... Apparatus ............................................................................................ Stimuli

...................................................................................... P roced u re ........................................................................................................ Resuits

........................................................................................ Accu racy .......................................................................................... Latency

Discussion ................................................................................................

Experiment2 ...................................................................................................... 20 Method ..................................................................................................... 21

................................................................................... Participants 21 Apparatus ..................................................................................... 21 Stimuli ........................................................................................... 21 Procedure ................................................................................... 21

Resutts ....................................................................................................... 22 ....................................................................................... Accuracy 22

Latency .......................................................................................... 23 Discussion .......................................................................................... 25

Experiment 3 ...................................................................................................... Method ..................................................................................................... . . ................................................................................... Parttapants

Apparatus ..................................................................................... Stimuli ...........................................................................................

..................................................................................... Procedu re Resuits .......................................................................................................

....................................................................................... Accu racy Latency ..........................................................................................

Discussion ................................................................................................

...................................................................................................... Experiment 4 Method ..................................................................................................... ... Participants ...................................................................................

..................................................................................... Apparat us ........................................................................................... Stimuli

..................................................................................... P roced u re Results .......................................................................................................

....................................................................................... Accu racy .......................................................................................... Latency

Discussion ................................................................................................

.......................................................................................... General Discussion 40

......................................................................................................... References 48

Tables .................................................................................................................. Table 1 ...................................................................................................... Table 2 ...................................................................................................... Table 3 ...................................................................................................... Table 4 ...................................................................................................... Table 5 ...................................................................................................... Table 6 ...................................................................................................... Table 7 ......................................................................................................

...................................................................................................... Table 8

................................................................................................................ Figures 62 Figure1 ..................................................................................................... 62

List of Tables

Table 1 : Mean Accuracy by Mode of Response and Target Format, Experimentl ................................................................................................... 54

Table 2: Mean Reaction Time by Mode of Response and Target Format, Experiment 1 ...................................................................................................... 55

Table 3: Mean Accuracy by Mode of Response and Target Format, Experirnent 2 .................................................................................................. 56

Table 4: Mean Reaction Time by Mode of Response and Target Format, Experirnent 2 ..................................................................................................... 57

Table 5: Mean Accuracy by Mode of Response and Target Format, Experiment 3 ................................................................................................. 5 8

Table 6: Mean Reaction Time by Mode of Response and Target Format, Experiment 3 ................................................................................................... 5 9

Table 7: Mean Accuracy by Mode of Response and Target Format, Expenment 4 ................................................................................................ 60

Table 1: Mean Reaction Time by Mode of Response and Target Format, Experiment 4 ...................................................................................................... 6 1

List of Figures

Figure 1 : Examples of experimental conditions ....................................... 62



General Introduction

Claims of a double dissociation between face and object recognition (e.g.,

Bentin, Allison, Puce, Perez, & McCarthy, 1996; Farah, 1990) have provided an

impetus for the study of facial recognition as distinct from other foms of recognition

(Newcombe, Metha, & de Haan, 1994). In fact, the selective nature of facial

recognition processing has been demonstrated through a variety of experimental

tasks (e.g., functional neuroimaging; Allison et al., 1994; facial inversion; Bartlett &

Searcy, 1993; Searcy and Bartlett, 1996) using both normal (Haxby et al., 1 994)

and brain-damaged (Moscovitch, Winocur, & Behrmann, 1997) human populations,

as well as animal species (Desimone, 1991; Yamane, Kaji, & Kawano, 1988), as

subjects. Moreover, research with young infants (Fagan, 1973) and children

(Peters, 1987) shows that they can discriminate reliably arnong different facial

stimuli. The selective nature of facial processing and the early onset of

discrimination suggests that processing faces is distinct from processing other

complex visual patterns.

Evidence of dissociations between face and object processing is exhibited

in a variety of experimental tasks. For example, recent studies involving functional

neuroimaging and ERP techniques confirrn that faces and objects differ in both the

pattern and location of electrophysiological and blood flow responses that they

evince (e.g., Allison et al., 1994a; 199413). In general, the amplitude of some ERP

waveforms is greater and latency is shorter to faces than to objects, with faces and

objects activating distinct loci in the same general location, usuaily the right

fusifon gyrus. In one fMRl study, McCarthy and his colleagues (McCarthy, Puce,

Gore, & Allison, 1994) reported that presentation of faces resulted in activation of a

srnall region located primarily in the right lateral fusiform gyrus. Similar findings

have been reported in studies involving monkeys as the subject population; these

studies (see for example, Bruce, Desimone, & Gross, 1981 ; Yamane, Kaji, &

Kawano, 1988) confirm that cells within the inferotemporal cortex respond

selectively to faces.

Neuropsychological studies of patient populations also lend support to

claims of a double dissociation between face and object processing, indicating that

these processes may be subserved by distinct neural substrates (Newcombe,

Metha, & de Haan, 1994). Whereas severe deficits in facial recognition

(prosopagnosia) are typically associated with bilateral damage in the region of the

fusiform gyrus, but can be elicited following rig ht-hemisphere damage alone

(Farah, IWO), impaired object recognition is usually linked to bilateral damage in

the same region, but can occur following damage to the left hemisphere alone. In

cases of impaired object or facial recognition, typically the opposing form of

processing is selectively spared (e.g., impaired facial recognition and relatively

intact object processing). The finding that such patients sornetirnes are able to

respond with detailed information when questioned regarding the attributes of

faces or objects that they fail to recognize confirrns that these deficits can occur at

the level of perceptual representation, rather than memory (Banich, 1997).

An additional line of evidence concerning possible dissociations between

face and object processing concems the differential effects of inversion on

recognition of faces and objects. The greater detrimental effect of inversion upon

face- than object-recognition is well-docurnented (e.g., Bartlett & Searcy, 1 993;

Diamond & Carey, 1986; Rhodes, Brake, & Atkinson, 1993; Searcy & Bartlett, 1996;

Yin, 1969). Specifically, inversion of faces relative to the viewer results in impaired

encoding; this effect is greater for faces than for most, but not al1 (Diamond & Carey,

1986; Yin, l969), other objects. Moreover, although dissenting opinions have

been expressed (e.g., Valentine, 1988, 1 W l ) , the available evidence (Bartlett &

Searcy, 1993, Rhodes et al., 1993; Searcy & Bartlett, 1996) suggests that inversion

has a greater effect upon the encoding and subsequent discrimination of the

spatial-relational (i.e., configurational) information contained in facial stimuli than it

does on discrimination of isolated facial components (e.g., eyes, ears, and mouth).

Indeed, several researchers maintain (see for example, Carey, 1978; 1981 ; Farah,

Tanaka, & Drain, 1995; Rhodes et al., 1993; Tanaka & Farah, 1993; Young,

Hellawell, & Hay, 1987) that whereas recognition of upright faces may rely upon

holistic or "configurational" (see Moscovitch et al., 1997; Yin, 1969) representation

schemes, recognition of inverted faces, much like objects, may rely upon part-

based decompositional strategies (see Marr & Nishihar, 1978 for an original

interpretation, as well as Biederman & Gerhardstein, 1993). Hence, recognition of

faces and objects may differ according to the degree of part-based decomposition

required for processing of the two types of stimuli, with recognition of upright faces

requiring little such decomposition or attention to component features of the face,

such as the eyes, nose, or mouth. Because faces are typically presented upright,

recognition performance for inverted faces may suffer as a result of the unfamiliar

part-based representations that accompany inversion (Haman & Moscovitch, in

preparation; Farah et al., 1995).

Several recent studies by Farah and her colleagues provide partial support

for these claims. Specifically, Tanaka & Farah (1 993) found that participants

performed more poorly when required to recognize isolated parts of upright faces

than when required to recognize the same components of inverted or scrarnbled

faces and objects. A later study (Farah, Tanaka, & Drain, 1995) revealed that

inversion effects are also apparent for non-face stimuli if participants are

encouraged to encode these stimuli as whole units or perceptual "gestalts", rather

than decompose them into parts. By contrast, treating faces like objects appears to

lessen the effects of inversion. Specifically, participants in the Farah et al. (1995)

study were required to study line drawings of unfamiliar faces in either whole form

or decomposed into parts. At test, participants were required to identify whole

faces presented either upright or inverted; inversion of the test faces resulted in

greater deficits when faces were studied as wholes rather than as parts. Hence,

initial representation of complex stimuli in a holistic form appears to result in

impaired recognition performance at inversion. The detrimental effects of inversion

are not as apparent, however, when stimuli are initially represented in a part-based

manner. A recent series of experiments by Harman and Moscovitch (in

preparation) replicated these findings using fractured (part-based) and intact

(upright and inverted) photographs of whole faces, while also suggesting that

format incongruency between study and test stimuli may have contributed to the

inversion effect. Taken together, the results of the studies by Farah and her

colleagues, as well as those of other researchers (Carey, 1978; 1981 ; Harman &

Moscovitch, in preparation; Moscovitch et al., 1997; Rhodes et al., 1993; Young,

Hellawell, & Hay, 1987) constitute strong evidence for daims of a dissociation

between face and object processing by suggesting that these processes may rely

upon two distinct mechanisms, one that is specialized for holistic or configurational

processing, and another that relies upon part-based representations.

Although dissenting opinions have been expressed (see for example,

Esgate, Burton, & Burton, 1996; Kreuger, 1978), the common observation voiced in

much of the literature is that whereas responding for same items may rely upon

rapid, global modes of processing, different responses may instead reiy on more

analytic or feature-based cornparisons (Bagnara, Boles, Simion, & Umiltà,, 1982;

Hock, 1973; Tzylor, 1 976a, 1976b). This pattern of responding may extend to the

processing of facial stimuli. For example, in one early study, Smith and Neilson

(1970) required participants to make a same-different judgment of schematic line

drawings of faces. At delays of 1 to 4 seconds, the number of features differing

between the two faces predicted the latency of different responses, with less tirne

being required for judgments of faces comprised of a greater number of different

features. Such effects were not apparent for same judgments, however; these

judgments were not affected by the total number of features present in the faces,

suggesting that participants did not engage in a serial comparison of the individual

features for these judgments, as was likely upon different responses. At delays of

10 seconds, however, both same and different judgrnents yielded a pattern of

results consistent with a reliance upon feature-by-feature comparison processes.

Although these findings (Smith 8 Neilson, 1970), as well as those of other

researchers (Bradshaw & Wallace, 1971), provide some evidence that processing

strategies for faces may Vary as a function of same versus different modes of

responding, with more holistic or configurational processing strategies being

associated with same judgments of facial stimuli, and more analytic or feature-

based comparisons being required for different judgments, particularly at short

retention intervals not requiring long-term or consolidated memory representations

(e.g., Bradshaw & Wallace, 1971 ; Smith & Neilson, 1970), such conclusions are

equivocal given viewers' reliance upon both holistic and feature-based strategies

for same and different judgments other studies of a similar nature (e.g., Sergent

1 984; Matthews, 1978).

The present experirnents will examine these daims in light of one aspect of

facial processing that has received much attention (e.g., Ellis, Shepard, & Davies,

1979; Nachson, Moscovitch, & Umiltà, 1995) in the recent literature: the

relationship between the internal and external facial features. Evidence of a

differential perceptual status for the intemal and externat features of facial stimuli is

seen in early infancy. Infants younger than two months of age typically limit their

visual scan to extemal facial features (Mauer & Salapatek, 1976). By contrast,

infants older than two months shift their gaze to internal facial features;

explanations for this effect have centered upon the optimal spatial frequencies

(Valenza, Simion, Cassisa, & Umiltà, 1996) of the stimuli, as well as their

differential complexity (e.g., Mauer, 1983). There is preliminary evidence

(Campbell & Tuck, 1995) to suggest that the recognition of farniliar faces follows a

similar pattern of development. Specifically, although younger children appear to

rely more heavily upon the external facial features for recognition, by age 10

recognition of familiar faces is achieved more efficiently by presentation of internal,

rather than external, facial features.

Other researchers (de Haan & Hay, 1986; de Haan, Young, & Newcornbe,

1987; Ellis et al., 1979; Hines, Jordan-Brown, & Juzwin, 1987; Moscovitch et al.,

1997; Nachson et al., 1995; Young, Hay, McWeeny, Flude, & Ellis, 1985) have

investigated the differential contribution of the internal and external features to the

recognition of familiar and unfamiliar faces in regards to adult populations. For

example, Ellis and his colleagues (Ellis, Shepard, & Davies, 1979) assessed

participants' reliance upon intemal and external features for identification.

Specifically, participants were requi red to identify familiar and unfamiliar faces

upon brief presentations of either the internal or external features. The results of

their study indicated that whereas participants appear to rely heavily upon the

information available in the internal facial features for identification of familiar faces,

there was no reliable difference in identification rates for unfamiliar faces when

participants were presented with internal or external features.

Later studies (de Haan & Hay, 1986; Hines, Jordan-Brown, & Juzwin, 1987;

Nachson et al., 1995; Young et al., 1985; see Moscovitch et al., 1997 for a different

experimental method) using matching tasks have revealed conflicting results

regarding the contribution of intemal and extemal features to the recognition of

familiar and unfamiliar faces. For example, whereas two studies (de Haan & Hay,

1986; Nachson et al., 1995) that used different experimental methods provided

evidence that external features are more efficacious than internal features in

matching tasks for unfamiliar faces, other studies [Ellis et al., 1979 (identification

task); Hines et al., 1987; Young et al., 19851 have failed to replicate this pattern of

findings. By contrast, the results of Young et al. (1985), as well as other

researchers (Campbell & Tuck, 1995; de Haan & Hay, 1986; Ellis et al., 1979)

converge on the finding that recognition of familiar faces is best achieved through

presentation of the intemal features.

Neuropsychological studies have also dernonstrated a pattern of diff erential

responding to internal and external facial stimuli. Ptischel and Zaidel (1994)

reported that removal of external facial features affected performance in a same-

different task when stimuli were presented to the right (left hemisphere) but not left

(right hernisphere) visual field. Hence, the left hemisphere may be less dependent

upon feature-dependent mechanisms, such as those found in the intemal features,

than is the right hernisphere. In a seemingly contradictory pattern of findings,

however, Young (1 984) reported a right-hemisphere superiority for recognition of

familiar faces from both internal and external features. This pattern of responding

was replicated in a later study by deHaan and Hay (1986) involving both normal

controls and patients with diffuse damage to either the left (LH) or right (RH)

hemisphere as the subject population. Normal controls exhibited a right-

hemisphere (left visual field) advantage for a sarne-different task requiring

participants to make judgments between a whole face and a face comprised of the

intemal or external features only. ln addition, patients suffering RH damage were

found to exhibit greater functional impairment for this task than were patients with

LH damage. A later neurophysiological study with monkeys as the subject

population (Horel, 1 993) indicated that bilateral cooling of the inferotemporal cortex

resulted in a severe irnpainent of monkeys' ability to perform a task that required

them to discriminate among different within-species faces that were identical

except for their internal features. Hence, although there is preliminary evidence of

a possible neurological (as well as functional) dissociation between the internal

and external features, the current status of this claim is equivocal at best.

Although there is preliminary evidence of a differential perceptual status for

the processing of internal and external features of facial stimuli, further

investigation is required to clarify the nature of the dissociability. Indeed, these

features may subsume distinct roles in facial recognition. A recent study by

Moscovitch and his colleagues (Moscovitch et al., 1997) that demonstrated

selective sparing of recognition w hen extemal featu res were inverted lends partial

support to this claim. Moscovitch and his colleagues recently compared facial

recognition in a patient (CK) with impaired object recognition, but intact facial

recognition processing, (Le., associative visual object agnosia and dyslexia; see

Behrmann, Winocur, & Moscovitch, 1992; Behnnann, Moscovitch, & Winocur, 1994

for a discussion in regards to this patient), to that of normal controls. Indeed, the

results of this research demonstrated that recognition of fractured and inverted

faces may rely upon the object-recognition system that is thought to be impaired in

this patient. In one experiment, the effects of inversion of the intemal versus

extemal features on recognition of a familiar face were compared. The results of

Moscovitch et al.'s experiment indicated that although inversion of the interna/

facial features resulted in irnpaired performance for both normal controls and CK,

the observed impairment in recognition was much greater for CK (drop of 60

percent versus drop of 20 percent in normal controls). By contrast, inversion of the

extemal features had no effect on recognition for either CK o r the controls. A

su bsequent experiment also resulted in impaired recognition performance when

the spatial relations among the internal features of a fractured face were disrupted;

again the detrimental effects of this manipulation were greater for CK than for

controls, suggesting that control subjects were able to rely on other mechanisms,

such as those used to identify objects, to aid in recognition.

Although it is possible that under conditions of inversion recognition is

subsumed by the individual features alone, Moscovitch and his colleagues

(Moscovitch et al., 1997) present recent evidence that renders this conclusion

unlikely. Specifically , the patient CK who demonstrated intact facial recognition,

but impaired object recognition, was able to recognize individual facial features as

well as controls, an indication that the facial-recognition system (which apparently

suffers breakdown under conditions of inversion) is attuned to these features. In

cases where CK was able to identify successfully inverted or fractured faces, he

sometimes appeared to do so through identification of separate features that were

especially salient (e.g., Prince Charles' large ears). Moreover, when he had

difficulty recognizing inverted cartoon faces, as well as overlapping objects and

Mooney figures (black and white pictures of objects and faces that are constructed

of patches of intense light and shadow), it appeared to be because he had difficulty

in appreciating the relation of the parts to the whole, an impairment that may have

hindered reintegration. Similarly. it is unlikely that facial recognition under

conditions of inversion is reliant upon mental rotation of inverted stimuli to an

upright position (Bartlett & Searcy, 1 993). Mental rotation of corn plex stimuli,

including faces, is impossible or highly error-prone (Rock, 1973). Hence, partial

reintegration or "normalization" of the disrupted facial features, as postulated by

Harman and Moscovitch (in preparation), as well as other researchers (Farah et al.,

1995), appears a likely possibility for recognition following inversion or other such

disruptions of facial processing.

Because inversion of the internal features affected recognition (as did

disrupting the spatial relations among the internal features of the fractured faces),

but inversion of the external features did not (Moscovitch et al., 1997), it appears

likely that the intemal features may carry the "burden of information" (p. 575) in

normal facial recognition. The relative importance of the different features under

conditions of impaired facial recognition processing (e.g., inversion), however, is

less clear. In the experiment conducted by Moscovitch and his colleagues, the

internal and external features were manipulated separately, yet in the context of a

whole face. For example, when the intemal features were inverted, the extemal

features remained upright and vice versa. Further research is necessary to clarify

the differential contribution of the internal and external features under conditions

that manipulate presentation of these features (e.g., full congruency of inversion).

One possibility suggested by Moscovitch and his colleagues is that the external

features (or facial contours) may be used as a frame or point of reference for

realignrnent of the internal features when they are impaired or fractured, acting as a

sort of perceptual "anchor" for reintegration or normalization. Indeed, several

researchers (Farah et al., 1995) have suggested that under conditions of inversion,

the locus of processing switches from that of the facial-recognition system to the

object-recognition system. Because it is apparent that the object-recognition

system has access to the extemal features (Moscovitch et al., 1997), it is possible

that it uses these features to guide reintegration. In fact, a similar proposal has

been made by Hurnphreys and his colleagues (Humphreys et al., 1994) in regards

to the perceptual reintegration of objects.

In the present series of experiments, we proposed to investigate differential

processing of the internal and external facial features through a series of

manipulations involving sarne-different judgments of unfamiliar faces. We

investigated these claims using an inversion paradigm by initially presenting

participants with upright faces with the external features either present (whole face

condition) or absent (internal features only) and later testing their ability to rnake

same-different judgments between these faces and a cornparison face that was

presented either upright or inverted. Whereas recognition of upright faces rnay be

subsumed by the facial-recognition system that relies upon holistic or

configurational processing strategies, the available evidence suggests that

recognition of inverted faces rnay be mediated by the object-recognition system

that relies upon analytic or part-based decompositional strategies for discrimination

(Moscovitch et . al., 1997). Although holistic or configurational processing

strategies required for the processing of upright faces rnay dictate attention to the

entire face, a reliance upon more part-based decompositional strategies requiring

attention to the individual facial features (e.g., eyes, nose, and mouth) rnay facilitate

responding to the internai features alone. We rnanipulated viewers' initial attention

to such features by presenting either an upright whole face or a part face at study.

Nonetheless, such strategies rnay be additionally mediated by responding to

upright same versus upright different cornparison items. Specifically, the results of

several earlier investigations (Bradshaw & Wallace, 1971 ; Matthews, 1978; Smith

& Neilson, 1970; Sergent, 1984) provide some preliminary evidence that whereas

responding to upright same items rnay rely upon holistic or configurational

processing strategies, responding to upright different items rnay rely upon analytic

or part-based decornpositional processing schemes. Although the available

evidence strongly suggests that the facial-recognition system relies predominately

upon holistic representation schemes to mediate recognition of upright faces

(Farah et al., 1995; Moscovitch et al., 1997), it is possible that performance for

same and different items requires this system to accommodate both holistic and

part-based representational schemes, respectively. By contrast, we did not expect

viewers' performance for inverted faces to be mediated by same versus different

modes of responding, instead relying chiefly upon part-based decomposition

schemes dictated by the object-recognition system (Biederman & Gerhardstein,

1993; Marr & Nishihar, 1978; Moscovitch et al., 1997).

Because the intemal features are thought to carry the burden of information

in facial recognition (Moscovitch et al., 1997), attention to these features may be

sufficient to f o m a discrimination judgment. Although recent evidence

accumulated by Moscovitch and his colleagues with the patient CU suggests that

this patient's difficulty in recognizing inverted (as well as fractured) faces may have

arisen from his inability to appreciate the relation of parts of these stimuli to the

whole (i.e., reintegration of the face to a perceptual gestalt), it is possible that

successful recognition performance following inversion is possible by attending to

the intemal features alone. An altemate possibility we considered was that the

preferential access accorded the external features by the object-recognition system

following inversion may allow these features to serve as an anchorhg point for

reintegration or normalization of disrupted facial stimuli. Because recognition of the

external features is not thought to be impaired following inversion (Moscovitch et

al., 1997), reintegration or normalization of facial stimuli may be required for the

internal features only. Hence, an additional aim of the current study was to

determine whether the internal and external features played a differential role in

discrimination performance upon upright and inverted presentations, perhaps as a

result of different processing strategies required for the discrimination of upright

(same and different) and inverted faces (Farah et al., 1995).

Experiments I and 2: lnitial Presentation of Whole Faces

Experiment 1 : Simultaneous Discrimination Task lnvolving Initial Presentation of

Whole Faces

Introduction. In the first experiment, participants were required to make a same-

different judgment of a test and comparison face presented simultaneously on

screen. Study faces were presented upright with both the internal and external

features present (whole face condition). By contrast, comparison faces were

presented either upright or inverted. Half of the comparison faces were presented

with both the internal and extemal features present (whole face); the remaining

faces were comprised of the intemal features only (part face). Because inversion of

faces relative to the viewer results in impaired perceptual encoding (see for

example, Bartlett & Searcy, 1993; Yin, 1969), this paradigm allowed us to compare

participants' ability to reliably discriminate different facial stimuli under conditions of

intact (upright) and impaired (inverted) facial processing.

Whereas recognition performance for inverted faces is thought to rely upon

part-based processing strategies mediated by the object-recognition system that

rnay require attention to individual parts of faces (Moscovitch et al., 1997),

recognition performance for upright faces rnay instead rely upon holistic processing

strategies requiring attention to the entire face. Moreover, the available evidence

(Bradshaw & Wallace, 1971 ; Smith & Neilson, 1970) suggests that performance for

same versus different upright faces rnay be additionally rnediated by holistic and

part-based decompositional processing strategies, respectively. Because initial

study presentations involved an upright whole face, we expected that participants

would rely upon holistic or configurational processing strategies at study. Indeed,

we expected these processing strategies to result in superior performance for the

presentation of whole rather than part same comparison faces that would also rely

upon holistic processing strategies for discrimination. By contrast, presentations of

whole comparison faces would no longer be favored upon upright different and al1

inverted comparison presentations, when discrimination performance rnay be

based upon individual consideration of the internal and extemai facial features.

One possibility we considered was that part-based processing strategies

associated with the recognition of inverted faces rnay lead to a reliance upon the

intemal features alone (part face condition) following inversion. Indeed, because

the intemal features are thought to carry the burden of information in facial

recognition, attention to these features alone rnay be sufficient to form a

discrimination judgment. If, however, the extemal features serve as an anchoring

point for reintegration following inversion (Moscovitch et al., 1997), we might expect

superior performance for inverted presentations of whole (intemal and external

features), rather than part, comparison faces following inversion. Because this

experiment involved sirnultaneous presentations of only two faces, responding

relied chiefly upon participantst perceptual representations of the stimuli, and was

unlikely to engage the rnemory systems directly.

Method

Participants. The participants were 24 members of the University of Toronto

at Mississauga comrnunity; five were male and 19 female. Al1 had either normal or

corrected-to-normal vision. Participants received nominal payment or academic

credit for their participation in the experirnent, which took approximately 20

minutes.

Apparatus. The stimuli were 16 unfamiliar faces, half male and half female,

taken from yearbook photographs and scanned into a computer file by a software

scanning prograrn (Picture Publisher 4.0, Micrografx) installed on a Computech

486-33 PC computer. Stimulus presentation and response recording were

controlled by a customized software program created by a commercially-produced

software program (MEL 2.0). Stimuli were presented via the computer screen on a

15-inch View Sonic 15GS monitor; participants used a response box connected to

a Pentium 166 PC computer to record their responses.

Stimuli The stimuli were unfamiliar faces (standards) scanned at a constant

level of contrast. Ail provided a frontal view of the face; sideways views were not

included (experimenter's judgment). The final size of the scanned images was 180

pixels wide by 250 pixels in height. Along with the study faces (upright position;

whole face), four different sets of comparison faces served as stimuli: i) upright

faces (whole face); ii) upright faces (intemal features only); iii) inverted faces

(whole face) and; iv) inverted faces (internal features only) (see Figure 1). The

intemal features of the face, consisting of the eyes, nose, and mouth, were cut out

with comparable pentagon-shaped tracing lines. Sixteen (eight male, eight female)

different standard faces were used to forrn the test and comparison faces. Each of

the sixteen standard faces seived as a study face and was manipulated to satisfy

the requirements of the four comparison conditions for a total of 64 comparison

faces. On each trial, the external features (when present) were identical across

study and comparison faces. Four different sets of external features were used.

Hence, four male faces shared the same external features; the remaining four male

standards shared a different set of external features, The same was true of the

female standards. Faces were matched such that when different cornparisons

were made, the internal features of the study and comparison faces were as similar

as possible (e.g., similarly shaped eyebrows or mouths). The stimuli were

presented as Greyscale (black-and-white) images on a white background.

---4 nsert Figure 1 about here-----

Each comparison face was presented twice (once as a same face and once

as a different face) alongside a study face in a different random order for each

participant for a total of 128 test trials. Sixteen practice trials (eight sarne, eight

different) were constructed from a different set of male faces. The practice trials

were identical to the test trials, with the exception that on different trials, the internai

features of the comparison faces differed more widely (e.g., incongruent shape of

mouth) from the study faces than was true on actual experimental trials.

Procedure. Participants were tested individually and received instructions

both verbally and on the cornputer screen. Their task was to make a same-different

judgment of a study and comparison face based on the internal features only.

Same, in this experiment, referred to full congruency between the internai features

of study and comparison faces; participants were instructed that differences

(including omission) between the external features of the study and comparison

faces were not to be considered in their judgment. At conclusion of the testing

session, few participants reported noticing that the external features were constant

(i.e., identical) across study and comparison presentations. Participants were

instructed to respond as quickly and as accurately as possible; both accuracy and

response-time data were recorded. Al1 trials were self-paced.

To eliminate possible hemispheric biases in responding, stimuli were

centered on screen, with study and cornparison faces vertically aligned. Study

faces consisting of both the interna1 and external facial features (whole face

condition) were presented at the top of the screen; comparison faces were

presented at the bottom of the screen. All trials (including the practice trials)

involved simultaneous presentations of the study and comparison faces. Stimuli

remained on screen until the initiation of a response by the participant. Following

responding, a fixation cross appeared on screen signaling participants to initiate a

new trial. Hand of responding was counterbalanced across participants.

Participants initially completed sixteen practice trials (eight same, eight

different), during which they were allowed to ask questions about the experimental

procedure. The actual test session consisted of 128 trials; sixty-four trials were

same trials, the remaining 64 were different trials. The test trials were presented in

a different random order for each participant.

Results.

Accuracy. Inversion of test faces resulted in decrements in viewer

performance. When the response data were analyzed by grouping responses for

same versus different presentations, however, it was revealed that holistic

processing strategies contributed to marginally (though not statistically significant)

superior performance upon upright same presentations of whole comparison faces

only (see Table 1 ). Hence, although differences in performance for upright and

inverted faces may have stemmed from either differences in format between test

and study faces (Harman & Moscovitch, in preparation) or in encoding strategies

used by viewers (Farah et al., 1995), accuracy scores exhibited little evidence of

the effects of holistic versus part-based processing strategies on discrimination of

part versus whole comparison faces.

----- lnsert Table 1 about here ----- These results were confirmed using a factorial ANOVA design. Means were

entered into a 2 (Mode of Responding: Same and Different) X 2 (Target Orientation:

Upright and Inverted) X 2 (Target Format: Part and Whole) factorial ANOVA with

Mode of Responding, Target Orientation, and Target Fona t treated as within-

subjects factors. The results of testing revealed a main effect of Target Orientation

(E(1, 23) = 1 17.64, g c .O01 ; upright faces were processed more accurately than

were inverted faces. Main effects of Mode of Responding also approached

significance, (E(1, 23) = 3.19, g c .09; viewers exhibited superior performance for

same than for different responses. Main effects for Target Format (E (1, 23) = .32, g

> .05) were non significant; there were no interactions between Mode of

Presentation and Target Orientation (E (1, 23) = 0.00, g > .05), Mode of

Presentation and Target Form (E (1 , 23) = 0.05, g > .05), or between Target

Orientation and Target Format (E (1, 23) = 1.76, g > .05). The three-way interaction

between Mode of Responding, Target Orientation, and Target Form also failed to

attain significance, (E (1, 23) = 1.29, g 2 .05).

Post-hoc comparison contrasts between faces presented upright and faces

presented inverted using the Ryan-Einot-Gabriel-Welsch multiple range q-test

(REGW-Q) confimed that discrimination performance for faces presented upright

was better than that for faces presented inverted (g c -05).

Latencv.

The results for the latency data were similar to those reported for the

accuracy data in that response time was faster for faces presented upright than it

was for faces presented inverted. When these data were analyzed by grouping

responses by mode of presentation (i.e., same versus different), however, it was

revealed that viewers exhibited superior performance for upright same

presentations of whole faces. By contrast, at inversion viewers exhibited little

differences in responding for part versus whole presentations of comparison faces,

regardless of the mode of responding required (see Table 2). No differences were

apparent in responding to whole versus part upright different comparison faces.

----- lnsert Table 2 about here -----

These results were confirmed using a 2 (Mode of Responding: Same and

Different) X 2 (Target Orientation: Upright and Inverted) X 2 (Target Format: Part

and Whole) factorial ANOVA with Mode of Responding, Target Orientation, and

Target Format treated as within-subjects factors. Medians were calculated for each

subject for each condition; only reaction times for accurate responses were

included in the analysis. In addition, we elirninated from the analysis al1 reaction

times that fell more than two standard deviations frorn the mean and calculated

new medians using the remaining data (see Ratcliff, 1993 for a discussion of the

treatment of reaction time outliers). This procedure resulted in elimination of less

than 4.3 percent of the total observations. The results of testing revealed a main

effect of Target Orientation (E(1, 23) = 21 -21, Q < .O01 ; upright faces were

processed more efficiently than were inverted faces. This result was confirmed by

post-hoc analysis using the REGW-Q (g < .05). There was also an interaction

between Mode of Responding and Test Orientation (E(1, 23) = 4.50, g c .OS) such

that differences in responding between upright and inverted faces were less

apparent for different (E(1, 23) = 38, g > .05) than for same (E(1, 23) = 4.03, g c .06)

responses. A three-way interaction between Mode of Responding, Target

Orientation, and Target Format (E (1, 23) = 577, p c .05) confimed that whereas

responding for upright same items varied as a function of part versus whole

presentations (E (1, 23) = 10.03, g < .01), responding did not Vary for either upright

different responses (E (1, 23) = 0.02, g > .05) or inverted same (E (1,23) = 1.41, g >

.05) and different (E (1, 23) = 0.37, g > .05) responses. Hence, viewers exhibited

superior performance for whole, rather than part, presentations of comparison

faces upon upright same presentations only. Main effects for both Mode of

Presentation (E (1 , 23) = .24, > .05) and Target Format (E (1, 23) = .29, g > -05)

were non significant; there were no interactions between Mode of Presentation and

Target Form (E (1, 23) = 2.58, g z .05) or between Target Orientation and Target

Format (E (1, 23) = 0.06, g > .05).

Discussion.

Faces presented upright were recognized more efficiently than were

inverted faces. In addition, whereas the results of the accuracy analysis provided

little evidence that responding varied as a function of part versus whole

presentations, the resuits of the latency analysis were clear in suggesting that

viewers exhibited superior performance for whole, rather than part, presentations of

upright sarne cornparison items. We speculate that such performance may arise

from a reliance upon holistic encoding strategies required for recognition of upright

same faces; these strategies may require attention to the entire face upon such

presentations.

By contrast, holistic encoding strategies resulting from study presentations of

an upright whole face may be incongruent with more part-based encoding

strategies required for the processing of upright different faces and al1 inverted

faces. These strategies may result in representation of whole comparison faces as

two separate parts, comprised of the internai and external facial features;

discrimination judgments following such representations may be based upon

individual consideration of the intemal and extemal features, mitigating any

advantages previously observed for whole faces. Indeed, viewers' tendency

toward part-based processing may have been counteracted by initial holistic

representations of the entire face.

We found no evidence that the external features serve as an anchoring point

for the reintegration of facial stimuli following inversion; performance was

equivalent for part and whole presentations of inverted cornparison faces.

Although this result favored our view that the intemal features may provide

sufficient information to form a discrimination judgment following inversion, the

equivalent performance observed for part and whole faces upon inversion

provided little evidence to support this claim. A second experiment, involving rapid,

sequential presentations of response items, was designed to heighten viewers'

initial reliance upon holistic processing strategies for upright study faces.

Experiment 2: Sequential Discrimination Task lnvolving Initial Presentation of

Whole Faces

Introduction.

In the first experiment, participants were required to make a same-different

judgment of a study and comparison face presented simultaneously on screen.

Because stimuli remained on screen until the initiation of a response, participants

may have relied on feature-by-feature comparisons between component parts of

study and comparison faces, rather than holistic or configurational encoding of the

images, to facilitate responding. We reasoned that conditions involving a higher

perceptual load (Le., more rapid encoding) would be more likely to result in

configurational or global processing (Bagnara, Boles, Simion, & Umiltà, 1982) of

upright faces by precluding, in part, the possibility that participants would be able to

rely on feature-by-feature comparisons between test and studied items (as when

stimuli remained on screen until responding) to facilitate responding. Hence, faces

were presented sequentially for a brief duration. In addition, a visual mask,

comprised of jumbled faces not seen in the experiment, was introduced between

presentations of the study and comparison faces; its purpose was to prevent

participants from forming an enduring perceptual representation of the initial study

face.

Although neither experiment 1 nor 2 allowed for an exploration of the effects

of long-terrn memory representation on subsequent discrimination, the rapid nature

of the stimulus presentations in the current experiment required that participants

form a judgment based upon their memory representations of the stimuli, perhaps

in working memory .

Method.

Partici~ants. The participants were 24 members of the University of Toronto

at Mississauga community; six were male and 18 female. All had either normal or

corrected-to-normal vision. Participants received nominal payment or academic

credit for their participation in the experiment, which took approximately 15

minutes.

Amaratus. The apparatus was identical to that in Experiment 1.

Stimuli. The study and comparison faces were identical to those in

Experirnent 1. In addition, a visual mask, comprised of the individual features of

several jurnbled faces, was introduced. The mask, like the study and comparison

faces, was a Greyscale image 180 pixels wide and 230 pixels in height presented

on a white background; it was created by mixing together the component parts of

several different faces not seen in the experiment.

Procedure. The procedure was identical to that in Experiment 1, with the

exception that in order to preclude the possibility of feature-by-feature cornparisons

between study and comparison faces, stimuli were presented sequentially for a

brief duration, with the introduction of a visual mask between study and cornparison

images. On each experimental trial, a study face consisting of both the intemal and

external features (whole face) was presented for 1 second (sec), followed by the

presentation of a visual mask for a 500 rnillisecond (rnsec) duration. lmrnediately

following presentation of the mask, a cornparison face appeared on screen for 1

sec. Stimuli, including the visual mask, were centered on the computer screen. All

trials were self-paced; following presentation of the cornparison face, a fixation

cross appeared on screen at which time participants were instructed to record their

responses and then initiate a new trial. As in Experiment 1, both accuracy and

response-time data were recorded.


different) during which they were allowed to ask questions about the experimental

procedure. The actual test session consisted of 128 trials; sixty-four were same

trials, 64 were different trials. Test trials were presented in a different random order

for each participant.

Results.

Accuracv. Performance in the second experiment was somewhat worse

than in the first experiment. Nonetheless, performance for both upright and

inverted faces appeared to be rnediated by holistic and part-based

representational strategies associated with the face- and object-recognition

systems, respectively (Farah et al., 1995; Moscovitch et al., 1997), as well as

differences in processing strategies for same and different facial stimuli (upright

faces only) (see Table 3).

-----Insert Table 3 about here-----

These results were confirmed using a factorial ANOVA design. Means were



Mode of Responding, Target Orientation, and Target Format treated as within-

subjects factors. The results of testing revealed a main effect of Target Orientation

(E(1, 23) = 117.64, g c .O01 and Mode of Responding (E(1,23) = 16.98, g c .O01 ;

upright faces were processed more accurately than were inverted faces and same

faces were processed more accurately than were different faces. A two-way

interaction between Mode of Responding and Target Format was also observed, (E

(1, 23) = 15.38, g < .OOl); planned contrasts confirmed that although performance

for upright faces differed as a function of same versus different modes of

responding (E (1, 23) = 49.09, g c .001), performance for upright faces did not (E

(1, 23) = 2.13, p < .05). The two-way interaction between Target Orientation and

Target Format also attained significance (E (1, 23) = 7.42, g < .02); a simple effects

analysis revealed that whereas viewers exhibited superior performance overall for

upright presentations of whole faces (E (1, 23) = 196.1, g < .001), superior

performance was observed for inverted presentations of part faces (E (1,23) =

103.0, p < Bol). Main effects of Target Format (E (1, 23) = 0.00, g > .05) were non

significant; there were no interactions between Mode of Presentation and Target

Orientation (E (1, 23) = 0.93, p > .OS), or between Mode of Responding, Target

Orientation, and Target Fomi (E (1, 23) = 2.95, > .05).

Post-hoc cornparison contrasts using the REGW-O between faces presented

upright and faces presented inverted and between same and different

presentations confirmed that discrimination performance for faces presented

upright was better than that for faces presented inverted and for same than for

different responses (es < .05) . Latencv. When the latency data were analyzed by grouping responses for

same versus different presentations, performance for inverted faces was somewhat

better for whole than for part faces, regardless of the mode of responding (i.e.,

same versus different) required (see Table 4). By contrast, performance for upright

faces was again rnediated by same versus different modes of responding.

Whereas performance for upright, same faces was best when comparison faces

were whole faces, performance for upright, different faces was best when

comparison faces were comprised of only part of the face (i.e., the intemal

featu res).





Target Format treated as within-subjects factors. As in Experiment 1, medians were

calculated for each subject for each condition; only reaction times for accurate

responses were included in the analysis. In addition, we eliminated from the

analysis al1 reaction times that fell more than two standard deviations from the

mean and calculated new medians using the remaining data. This procedure

resulted in elirnination of less than 3.7 percent of the total observations. Testing

revealed a main effect of Target Orientation (E(1, 23) = 30.65, g < .001); upright

faces were processed more efficiently than were inverted faces. This result was

confirrned by post-hoc analysis using the REGW-Q (e c .05). There was also a

main effect of mode of responding (E(1, 23) = 7.87, Q < .O2 ), with faster responses

being made for same than for different presentations (REGW-Q, g < .05). A three-

way interaction between Mode of Responding, Target Orientation, and Target

Format (E (1, 23) = 5.77, g < .05) confirmed that viewers exhibited the greatest

differences in performance between whole and part presentations of comparison

faces following upright same presentations (E (1, 23) = 10.03, g c .01). Main effects

of Target Format (E (1, 23) = 2.1 1, g > .05) were non significant; there were no

interactions between Mode of Presentation and Target Orientation (E (1, 23) = 1.47,

Q > .05), Mode of Presentation and Target Form (E (1, 23) = 2.75, p > .05), or

between Target Orientation and Target Format (E (1, 23) = .48, g z .05).

Discussion. The results of Experiment 2 both confinned and extended our earlier

observations in Experiment 1. The main finding of both experiments was that

differential processing strategies associated with the recognition of upright and

inverted faces (Farah et al., 1995; Moscovitch et al., 1997), as well as responding to

same versus different upright faces (Bradshaw & Wallace, 1971 ; Matthews, 1978;

Smith & Neilson, 1 970; Sergent, 1 984), appear to rnediate viewers' responses to

facial stimuli.

Performance in Experiment 2 was best for whole, rather than part,

presentations of upright same faces. By contrast, whereas viewers exhibited more

accurate performance for whole presentations of upright different faces, response

latency was actually faster for part presentations of these faces, suggesting a

speed-accuracy trade-off; the more accurate responses observed for whole faces

upon different responses may reflect the longer amount of processing time

accorded these stimuli (i.e., responses were approximately 83 msec slower to

whole than to part comparison faces).

The observed disparities in responding for upright faces in Experiments 1

and 2 may stem from differences in the processing of same and different faces. In

both experiments, viewers exhibited superior performance for same presentations

of whole rather than part comparison faces, likely reflecting a reliance upon holistic

encoding strategies requiring attention to the entire face. By contrast, we found

little evidence of differences in responding to part versus whole faces upon upright

different presentations. We speculate that an initial reliance upon holistic encoding

strategies at study of whole faces may have counteracted more part-based

representations of upright different faces, that may have relied upon separate

consideration of the intemal and extemal features. Hence, we observed few

differences in performance for part versus whole comparison faces upon such

presentations.

The results of the accuracy and latency data for inverted faces in Experiment

2 were somewhat contradictory in suggesting that whereas viewers exhibited more

accurate performance for part rather than whole presentations of companson faces,

efficiency was sornewhat better for whole than for part presentations. Most notably,

performance was approximately 100 msec faster for whole presentations of

inverted different faces, while responding in the same condition was more accurate

for part faces. Nonetheless, the low viewer accuracy (approximately 55 percent

correct, a response rate only slightly above chance) in this condition resulted in

only slightly more than half of viewers' responses being included in the analysis of

the response data. This observation, coupled with the only slight differences in

latency for inverted same presentations, suggest that for inverted presentations in

Experiment 2, accuracy may be the best reflection of participant responding.

The superior accuracy observed for part faces upon such presentations

constitutes strong proof for out- daim that performance for inverted faces may be

mediated by part-based representational strategies associated with the object-

recognition system (Moscovitch et al., 1997); such strategies may result in attention

being focused upon the intemal features alone. Because these features may carry

the burden of information in facial recognition (Moscovitch et al., 1997), it is likely

that attention to these features is sufficient for recognition. In fact, the extemal

features may prove an unnecessary distraction at test when performance is driven

by feature-based cornparisons that are most readily available via the interna1

features.

Thus, although the task demands of Experiment 2 appeared to dictate more

global responding to upnght stimuli than was true in Experiment 1, we nonetheless

observed differential processing as a consequence of part versus whole

presentations of inverted comparison faces. That no evidence of superior

performance was found for inverted presentations of comparison faces comprised

of both the internal and external features strongly suggested that the extemal

features do not play a role in the reintegration or nonnalization of facial stimuli

following inversion.

Although the results of two previous studies (de Haan & Hay, 1986; Nachson

et al., 1995) suggest that the external features are more efficacious than the

intemal features in forming discrimination judgments for unfamiliar faces, the

findings of several other researchers (Ellis et al., 1979; Hines et al., 1987, Young et

al., 1985) are contradictory in that they found no reliable difference in identification

rates for unfamiliar faces when participants were presented with the internal or

external facial features. Nonetheless, participants in these studies were required to

make discrimination judgments of upright faces only. The results of the present

study suggest that part-based decornpositional strategies may result in a reliance

upon the internal rather than external features to form a discrimination judgrnent for

unfamiliar faces following inversion. Moreover, participants in both Experirnents 1

and 2 exhibited superior performance for presentation of both the internal and

external facial features upon upright same presentations of comparison faces,

suggesting that the extemal features aid in recognition performance for upright

same presentations of comparison faces. It is worth noting, however, that such

performance may be related to holistic processing strategies dictating attention to

the entire face, a factor seldom considered in determining the efficacy of the

internal and external features in forming discrimination judgments.

Experiments 3 and 4: Initial Presenta tion of Interna1 Fea tures

Experiment 3: Simultaneous Discrimination Task lnvolving Initial Presentation of

lntemal Features

Introduction. In a second set of experirnents, we sought to examine whether initial

presentation of the internal features only (part face) would heighten reliance upon

these features for discrimination. We reasoned that by focusing viewers' attention

on the internal features at study, it was likely that attention would continue to be

focused on these features at test.

In the present series of experirnents, initial encoding of the intemal features

was expected to result in superior performance being observed for part rather than

whole comparison faces, regardless of the orientation of test stimuli or the mode of

responding required. Specifically, although initial study presentations may still

have relied upon holistic encoding of an upright face, such faces were comprised

of the intemal features alone. Hence, initial viewer representations subsurned

these features only. Upon upright same presentations, holistic encoding of the

internal features at study was expected to focus attention on these features at test

(part face). By contrast, presentations of whole same faces were expected to result

in holistic encoding of the entire comparison face; such representations would be

incongruent with viewers' initial representations of the internal features alone.

Because upright different and al1 inverted presentations may rely upon part-

based encoding strategies, we again expected to observed superior performance

for part, rather than whole, presentations of corn parison faces. Indeed, evidence

accurnulated in Experiments 1 and 2 led us to betieve that the external features

may prove distracting at test when attention is focused upon the internal features

alone. Because part-based decompositional strategies require attention to

individual facial features such as the eyes, nose, and mouth, it is apparent that the

internal features which contain such information, may be the focus of viewer

attention when such strategies are required, thereby heightening the perceptual

saliency of these features. We did not expect, however, to observe as great of a

magnitude of difference in responding to part versus whole cornparison faces upon

such presentations as was expected for upright same presentations of comparison

faces. Although initial representations of the intemal features alone at study may

require that viewers "disentangle" these features from the whole upon cornparison

presentations of an entire face, this process would be far less difficult than for

upright same presentations that result in holistic or blended, rather than separate

representations, of the internal and extemal features.

Participants. The participants were 24 mernbers (mean age = 21 -96 years;

rnean years of education = 16.78) of the University of Toronto at Mississauga

community; nine were male and 15 female. Al1 had either normal or corrected-to-

normal vision. Participants received either nominal payrnent or academic credit for

their participation in the experiment, which took approximately 1 5 minutes.

Amaratus. The apparatus was identical to that in Experiments 1 and 2.

Stimuli. The stimuli were the same as those in Experiments 1 and 2. The

present experiment differed from Experiment 1 and 2, however, in that study faces

consisted of the intemal features only. Hence, on each experimental trial,

participants were required to make a same-different judgment of an upright test

face (internal features only) and one of four possible comparison faces: i) upright

faces (whole face); ii) upright faces (intemal features only); iii) inverted faces

(whole face) and; iv) inverted faces (internal features only). Whereas study faces

were always presented upright, comparison faces consisting of either the entire

face or internal features alone were presented either upright or inverted.

Procedure. The procedure was identical to that in Experiment 1, with the

exception that study faces consisted of the internal featu res only. Stimuli were

presented centered on screen, with study and comparison faces vertically aligned.

Study faces, consisting of the interna1 features only, were presented at the top of

the screen; comparison faces consisting of either the entire face or the intemal

features alone were presented either upright or inverted at the bottom of the

screen.


different), during which they were allowed to ask questions about the experimental

procedure. The actual test session consisted of 128 trials; siw-four trials were

same trials, the remaining 64 were different trials. Test trials were presented in a

different random order for each participant.

Results.

Accuracv. Inversion of test faces again resulted in decrements in viewer

performance. When these data were analyzed by same versus different

responding (see Table 5), superior performance was again observed for upright

presentations of part comparison faces.


These results were confirmed using a factorial ANOVA design. Means were

entersd into a 2 (Mode of Responding: Same and Different) X 2 (Target Orientation:

Upright and Inverted) X 2 (Target Format: Part and Whole) factoria! ANOVA with


subjects factors. The results of testing revealed main effects of Target Orientation

(E(1, 23) = 51.03, g == .O01 , Target Format (E(1, 23) = 8.97, g < .01, and Mode of

Responding (E(1,23) = 12.00, g < .01. Thus, upright faces were processed more

accurately than were inverted faces and part faces were processed more

accurately than were whole faces. In addition, responses to same items were more

accurate than those to different items. A two-way interaction between Mode of

Responding and Target Format was also observed, (E (1,23) = 9.06, < .01); a

simple effects analysis revealed performance for part faces varied more as a

function of same versus different modes of rssponding (F: (1, 23) = 65.69, g c -001)

than did performance for whole faces (E (1,23) = 14.81, g c .001). The two-way

interaction between Mode of Responding and Target Format was not significant (E

(1,23) = 2.59, g > .05) nor was that between Target Orientation and Target Format

(E (1,23) = .07, Q > .05). A three-way interaction between Mode of Responding,

Target Format, and Target Orientation was not observed, (E (1, 23) = 1.80, g > .05).

Post-hoc comparison contrasts (REGW-Q) between upright and inverted

faces confimed that discrimination performance for faces presented upright was

better than that for faces presented inverted (g < .05); viewers also exhibited

superior performance for part rather than whole presentations of comparison faces

(REGW-Q, e .05) and for same rather than different responses (REGW-O, g c .05).

Latencv. Similar to the accuracy data, response times were faster for faces

presented upright than for faces presented inverted. Superior performance was

also obseived for upright presentations of part rather than whole faces, regardless

of whether a same or different response was required (see Table 6). Similarly,

presentation of parf faces resulted in superior performance for inverted faces, but

for same responses only.




Target Format treated as within-subjects factors. As in Experiments 1 and 2,

medians were calculated for each subject for each condition; only reaction times for

accurate responses were included in the analysis. In addition, we eliminated from

the analysis al1 reaction times that fell more than two standard deviations from the

mean and calculated new medians using the remaining data. This procedure

resulted in elimination of less than 3.7 percent of the total observations. This

procedure resulted in elirnination of less than 3.8 percent of the total observations.

Testing revealed a main effect of Target Orientation (E(1, 23) = 31.47, p c .001);

upright faces were processed more efficiently than were inverted faces. There was

also a main effect of Target Format (E(1, 23) = 26.70, Q c .001); part faces were

processed more efficiently than whole faces. These results were confirmed by

post-hoc analysis using the REGW-Q (g e .05).

A two-way interaction was observed between Mode of Presentation and

Target Format (E (1, 23) = 6.85, g c .OS); differences between modes of responding

(same versus different) were more evident for comparison presentations of part (E

(1, 23) = 18.34, g < ,001) rather than whole (E (1,23) = .34, > .05) faces. The

three-way interaction between Mode of Responding, Target Orientation, and Target

Format also approached significance (E (1, 23) = 3.70, Q c .07); although it was

readily apparent that viewers exhibited superior performance for part, rather than

whole, presentations of comparison faces upon upright same (E (1, 23) = 37.87, c

.001) and different (E (1, 23) = 30.77, e c .001) presentations, as well as inverted

same presentations (E (1, 23) = 28.24, g c .001), such differences were not as

apparent following inverted different trials (E (1, 23) = 0.74, Q > .05).

Main effects of Mode of Responding (E (1, 23) = 1.75, g z .05) were not

significant nor were there any interactions between Mode of Presentation and

Target Orientation (E (1, 23) = 1.56, g > .05) or between Target Orientation and

Target Format (E (1, 23) = 2.30, Q > .05).

Discussion. In Expet-iment 3, superior performance was observed for upright,

rather than inverted, presentations of comparison faces. Moreover, the results of

the accuracy data indicated that viewers exhibited superior performance for part

than for whole presentations of comparison faces. Responding was faster to part

than to whole comparison faces upon al1 upright trials, as well as for inverted same

responses. These results confimed Our earlier hypothesis that initial presentation

of the interna1 features alone would result in superior performance being observed

for part rather than whole comparison faces. Although faster responding for part

than for whole comparison faces was not observed upon different inverted

presentations, an inspection of the response data indicates that this non significant

finding may stem from the greater amount of time viewers required to make a

judgment of a part face on different trials (as cornpared to inverted same trials);

different presentations may have encouraged viewers to attend more closely to

individual facial features than was true upon same presentations (e.g., Matthews,

1978; serial processing for different faces only).

As we had predicted, the greatest magnitude of difference in responding to

part rather than whole comparison faces occurred for upright same presentations

[approximately 690 milliseconds as cornpared to 572 (upright different), 597

(inverted same), and 96 (inverted different) milliseconds]. Holistic processing

strategies for upright same faces likely resulted in global encoding of the entire

face upon comparison presentations of the entire face, requiring viewers to

disentangle the interna1 features from their holistic representation upon such trials.

Although such parsing would be required upon upright different and inverted

presentations of whole faces as well, part-based encoding strategies likely

resulted in separate representations of the intemal and external facial features,

making this process easier to accomplish. Moreover, part-based processing

strategies focusing attention upon the intemal features alone may have heightened

the perceptual saliency of these features upon such judgments. Although overall

responding to part and whole faces was slower for upright different and al1 inverted

presentations than it was for upright same faces, it was likely that the slower

response times observed for these stimuli can be attributed to the piecemeal nature

of responding to these items, when compared to the more rapid or global nature of

responding to upright same items.

Indeed, the results of the present experiment lend confirmation to our earlier

hypothesis that the extemal features rnay prove disruptive at test when

discrimination judgments can be fonned based upon the internal features alone.

The slower and less accurate responding observed for presentations of

comparison faces comprised of both the internal and external features for al1

upright presentations, as well as inverted sarne responses, indicates that these

features add no new or informative information for discrimination. Rather, it

appears that these featu res rnay prove disruptive at test when attention rernains

focused on the internal features. Indeed, these findings allow us to more strongly

reject our hypothesis that the external features serve as an anchoring point for

reintegration or norrnalization of facial stimuli following inversion; performance was

worse when the extemal features were present than when they were absent.

Experiment 4: Sequential Discrimination Task lnvolving Initial Presentation of the

Intemal Features

Introduction.

Because the third experiment involved simultaneous presentations of test

and comparison items that may have allowed for direct feature-by-feature

cornparisons to occur, we reasoned that a sequential paradigm like that used in

Experiment 2 would preclude the possibility that participants could rely upon this

mode of responding to facilitate discrimination. Hence, the procedure used in

Experiment 4 was identical to that in Experiment 2, with the exception that at study

faces consisted of the intemal features only. We reasoned that this paradigm may

result in more global encoding of test stimuli, at least upon initial study

presentations, than may have been true in Experiment 3, where participants would

have more opportunity to rely upon feature-by-featu re corn parisons than was

possible under the present experimental paradigm. Indeed, we expected that the

lack of difference in response times for part versus whole faces observed upon

inverted different presentations in Experiment 3 might be eliminated under the

present paradigm which required participants to retain a holistic representation of

the internal features presented at study and make judgments based upon their

mernory representations of the stimuli.

Participants. The participants were 24 members (mean age = 20.88; mean

years of education = 1 6.79) of the University of Toronto at Mississauga community;

seven were male and 17 female. AI1 had either normal or corrected-to-normal

vision. Participants received either nominal payment or academic credit for their

participation in the experirnent, which took approximately 15 minutes.

Apparatus. The apparatus was identical to that in the preceding

experiments.

Stimuli. The stimuli were identical to those in Experiment 2, with the

exception that comparison faces consisted of the internal features of the face only.

Procedure. The procedure was identical to that of Experiment 2, with the

exception that study faces consisted of the internal features only.

Results.

Accuracv. Inversion of test faces again resulted in decrements in viewer

performance. When these data were analyzed by same versus different modes of

responding, superior performance was again observed for upright and inverted

presentations of part comparison faces (see Table 7).

---4 nsert Table 7 about here-----

These results were confimed using a factorial ANOVA design. Means were




subjects factors. The results of testing revealed main effects of Target Orientation

(E(l,23) = 37.88, Q < ,001, Target Format (E(1, 23) = 24.70, g .001, and Mode of

Responding (E(1.23) = 21.67, p c .OUI. Thus, upright faces were processed more

accurately than were inverted faces and part faces were processed more

accurately than were whole faces. In addition, responses to sarne items were more

accurate than those to different items. A two-way interaction was also observed

between Mode of Responding and Target Orientation, (E (1,23) = 9.29, g c .01);

planned contrasts revealed performance varied more as a function of same versus

different modes of responding (E (1, 23) = 56.41, g < .001) than did performance for

inverted faces (E (1, 23) = 10.24, g < .01). The three-way interaction between Mode

of Responding, Target Format, and Target Orientation (E (1, 23) = 4.17, g > .06) was

marginally significant. Planned comparisons revealed that performance accuracy

less as a function of part versus whole presentations for upright same comparison

faces (E (1, 23) = 3.72, g >.05), than for upright different, (E (1, 23) = 30.26, g c

.001) and inverted same (E (1,23) = 17.44, Q .001) and different (E (1, 23) =

13.44, g < .01) faces. The two-way interaction between Mode of Responding and

Target Format was not significant (E (1, 23) = .43, g > .05) nor was that between

Target Orientation and Target Format (E (1, 23) = .03, g > .05).

Post-hoc comparison contrasts (REGW-Q) between upright and inverted

faces confirrned that discrimination performance for faces presented upright was

better than that for faces presented inverted (e c .05); viewers also exhibited

superior performance for part than for whole presentations of cornparison faces

(REGW-Q, g < .05) and for same rather than different responses (REGW-Q, e c .05).

Latencv. Response times were faster for faces presented upright than for

faces presented inverted. More interestingly, however, responding was faster to

part rather than whole presentations of comparison faces, regardless of mode of

responding (same versus different) required or the target orientation (upright

versus inverted) of stimuli (see Table 8).

-----ln sert Table 8 about here-----




Target Format treated as within-subjects factors. As in Experiments 1 and 2,

medians were calculated for each subject for each condition; only reaction times for

accurate responses were included in the analysis. In addition, we eliminated from

the analysis al1 reaction tirnes that fell more than two standard deviations from the

rnean and calcuiated new rnedians using the remaining data. This procedure

resulted in elimination of less than 3.6 percent of the total observations. Testing

revealed a main effect of Target Orientation (E(1, 23) = 24.74, c .001); upright

faces were processed more efficiently than were inverted faces. There was also a

main effect of Target Format (E(1, 23) = 27.28, g c .001); part faces were processed

more efficiently than were whole faces. A main effect of mode of responding (E(1,

23) = 8.65, g c .Ol) revealed that same presentations resulted in faster responding

than was observed for different responses. These results were confined by post-

hoc analysis using the REGW-Q (g e .05).

A two-way interaction was observed between Mode of Presentation and

Target Orientation (E (1, 23) = 6.85, g c .05); differences between modes of

responding (same versus different) were more evident for comparison

presentations of upright than inverted faces. In contrast to Experiment 3, however,

the three-way interaction between Mode of Responding, Target Orientation, and

Target Fonat was not significant (E (1, 23) = .23, g > .05); response performance

was better for presentation of part rather than whole comparison faces regardless

of mode of responding and target orientation. There were no interactions between

Mode of Presentation and Target Format (E (1, 23) = .33, g > .05) or between Target

Orientation and Target Format (E (1 , 23) = 1.43, g > .05).

Discussion. The results of Experiment 4 were relatively clear in suggesting that

initial attention to the internal features alone heightened viewers' reliance upon

these features at test. Similar to the results reported in Experiment 3, viewers

exhibited faster and more accurate performance for part rather than whole

presentations of comparison faces. Whereas in Experiment 3, however,

differences in response time were not apparent for inverted different cornparison

faces, the present experimental paradigm appeared to heighten viewers' reliance

upon holistic encoding at least upon initial presentation of an upright study face,

resulting in superior performance being obsetved for part than for whole

comparison faces, regardless of the orientation of test faces, or the mode of

responding required.

We once again observed the greatest differences in response time to part

versus whole faces upon upright presentations of sarne comparison faces.

Although the three-way interaction between Target Orientation, Target Format, and

Mode of Responding did not prove to be significant, performance for upright same

comparison faces varied by approximately 196 msec for part versus whole

comparison faces, as compared to 150 msec for upright different responses and

11 9 and 75 msec for inverted same and different presentations, respectively.

Hence, viewers appeared to have the greatest difficulty disentangling the internal

features from holistic representations of the entire face encouraged by global

responding to upright same presentations. Although overall responding to part and

whole faces was slower for those comparison faces that appeared to rely upon

part-based processing strategies (i.e., upright different and al1 inverted

presentations) than it was for upright same faces, it was likely that the slower

response times observed can be attributed to the piecemeal nature of responding

to these items, when compared to more rapid or global responding to upright same

items. Moreover, although greater differences in accuracy were observed for part

versus whole presentations for upright different and al1 inverted comparison

presentations than for upright same responses, the near-ceiling accuracy in this

condition (approximately 94 percent for part faces and 90 percent for whole faces)

may have precluded the emergence of any substantial differences in accuracy for

upright same faces.

Part-based encoding strategies once again appeared to result in a focus of

attention upon the internal features; superior performance was observed for part

rather than whole presentations of comparison faces. Indeed, initial attention to the

internal features alone rnay have rendered the external features distracting at test,

such that superior performance was observed when these features were absent

rather than present. Although viewers' initial holistic representation of a part face at

study rnay have required them to disentangle the internal features from the whole

face upon upright same presentations of the internal and extemal features, the

heightened perceptual saliency of the internal features, as well as separate

representations of the internal and external features that likely occurred as the

result of part-based decompositional processing strategies, for upright different and

al1 inverted presentations may have facilitated this process for these presentations.

Although recent evidence accumulated by Moscovitch and his colleagues

(Moscovitch et al., 1997) with the patient CK suggests that his difficulty in

recognizing inverted (as well as fractured) faces may have arisen from an inability

to appreciate the relation of parts of these stimuli to the whole (i.e., reintegration of

the face to a perceptual gestalt), the results of the present series of experiments are

consistent with those of Experiments 1 and 2 in suggesting that successful

recognition performance following inversion is possible by attending to the internal

features alone. Moreover, whereas viewers in Experiment 1 and 2 exhibited

superior performance for upright same presentations of whole faces comprised of

both the intemal and external features, viewers in the second series of experiments

were better able to form their discrimination judgments in this condition based on

consideration of the internal features alone. It is likely that initial attention to these

features alone upon upright study presentations heightened later reliance upon the

intemal features for discrimination. Hence, although two studies (de Haan & Hay,

1986; Nachson et al., 1995) that used different experimental methods provided

evidence that external features are more efficacious than internal features in

recognition tasks for upright unfamiliar faces, the results of the present series of

experiments suggest that these features rnay prove distracting at test when

attention is focused on the intemal features alone at study.

General Discussion

The central issue addressed in this study was whether differences in

processing strategies for upright and inverted faces (Farah et al., 1995; Moscovitch

et al., 1 997; Tanaka & Farah, 1 993), as well as in same versus different modes of

responding to upright faces (Bradshaw & Wallace, 1971; Matthews, 1978; Smith &

Neilson, 1970; Sergent, 1984) would mediate responding to upright and inverted

comparison faces comprised of either the internal and external features orthe

internal features alone. An additional aim of the present study was to determine

whether the internal and external features played a differential role in

discrimination performance upon upright and inverted presentations. Our results

provide new evidence that whereas holistic processing strategies mediate

responding to upright same facial stimuli, more analytic or part-based

decompositional strategies rnay be responsible for the processing of upright

different and al1 inverted facial stimuli. Moreover, attending to the internal features

alone was sufficient to form a discrimination judgment for upright different and al1

inverted faces; the same was true for upright same faces when attention was

focused on the internal features alone ai study. By contrast, viewers relied upon

both the internal and external features to form a discrimination judgment for upright

same faces when attention was focused on the entire face at study.

We found no evidence that the external features seive as an anchoring point

for reintegration or normalization of facial stimuli following inversion. Rather, the

superior performance observed upon inverted presentations in Experiment 2 and

across al1 presentations in Experirnents 3 (with the exception of inverted different

presentations) and 4, when the external features were absent, rather than present,

suggests that these features rnay prove disruptive at test when attention is focused

upon the internal features alone.

Our findings were consistent with the suggestion that different processing

strategies may rnediate responding to same versus different presentations of

upright faces (Bradshaw & Wallace, 1971 ; Matthews, 1978; Smith & Neilson, 1970;

Sergent, 1984). Whereas two early studies (Bradshaw & Wallace, 1971 ; Smith &

Neilson, 1970) provided some preliminary evidence that responding to upright

different items at short retention intervals (simuitaneous presentations, as well as

delays of up to 4 sec between presentations of test and comparison faces) relies

predominately upon feature-by-feature processing strategies, the results of later

studies (Matthews, 1978; Sergent, 1984) were contradictory in that they

demonstrated that responding to these stimuli rnay rely upon both holistic and part-

based encoding strategies. The results of the current investigation indicate that

whereas responding to upright sarne faces may rely upon holistic or configurational

processing strategies dictating attention to the entire face, responding to upright

different items may instead rely upon more feature-based or analytic processing

mechanisms dictating attention to the internal features alone, which appear to carry

the burden of information processing in facial recognition (Moscovitch et al., 1997)

When initial study presentations involved whole faces, performance was better for

whole than for part presentations of upright same comparison faces. By contrast,

initial encoding of a whole face at study appeared to overwhelm more part-based

representations of upright different comparison faces at test, resulting in no

differences being obsewed in performance for upright different presentations in

Experiments 1 and 2.

When initial study presentations involved the intemal features alone,

however, performance upon upright same presentations was best for part rather

than whole presentations of comparison faces; difficulties in disentangling the

intemal features from holistic representations of whole comparison faces may

account for this finding. Performance for upright different responses was also

better for part than for whole presentations of comparison faces, although the

magnitude of difference between part and whole presentations of cornparison

faces was not as great as for upright same presentations, suggesting that separate

representation of the intemal and external features, as well as the heightened

salience of the intemal features as a result of part-based encoding strategies, may

have made it easier for viewers to disentangle the part from the whole upon such

presentations.

It is worth noting that, similar to the Matthews (1978) and Bradshaw and

Wallace (1 971 ) investigations, our experiments involved either simultaneous

presentations of study and comparison stimuli, or brief one-second delays between

study and test presentations. It is unclear whether differences in responding to

same and different items would emerge at longer retention intervals that may rely

more upon long-term or consolidated memory representations. Nonetheless,

although processing of upright faces appears to rely predominately upon holistic

encoding strategies described by other authors (e.g., Farah et al., 1995; Yin, 1969),

it is clear that facial-recognition system is able to accommodate the part-based

representations that rnay be required for processing of different faces. Whether

such representations rely upon serial processing mechanisms, however, while

responding to same items relies upon more parallel processing mechanisms is one

interesting area awaiting further investigation.

We speculate that part-based decompositional strategies encouraged by the

object-recognition systern that appears to be responsible for the processing of

inverted faces (Farah et al., 1995; Moscovitch et al., 1997) may have dictated a

focus of attention on the internal features alone at inversion, resulting in superior

performance being observed for part rather than whole presentations of

cornparison faces in Experiments 3 (with the exception of different responses) and

4; viewers also exhibited superior performance for part faces at inversion in

Experiment 2. No evidence was found that the external features, which appear to

have preferential access to the object-recognition system following inversion

(Moscovitch et al., 1997), aided in the perceptual reintegration or nonalization of

inverted stimuli. Because it is apparent that the intemal features carry the burden

of information in facial recognition processing, i t appears that attention to these

features alone is sufficient to form a discrimination judgment under conditions of

inversion. Moreover, because part-based decompositional strategies require

attention to individual facial features such as the eyes, nose, and mouth, it is

apparent that the internal features, which contain such features, are the likely focus

of attention when such strategies are required.

Because part-based decompositional strategies may focus attention on the

internal features at test, as well as facilitate separate representations of the intemal

and external features following comparison presentations of whole faces, we did

not observe as great of differences in responding to part versus whole inverted

faces as we did for upright same items in Experiments 3 and 4. We speculate that

the heightened perceptual saliency of the intemal features, as well as the

individual consideration allowed the internal and external features due to part-

based encoding strategies, may have made it easier to disentangle the intemal

features upon comparison presentations of whole inverted faces. Indeed, the

external features may prove distracting at test under such conditions; we also

observed interference by the external features upon both upright same and

different presentations in Experiments 3 and 4, suggesting that when attention is

focused primarily upon the intemal features alone these features may prove

distracting, regardless of the orientation of the stimuli.

Although the results of two previous studies (de Haan & Hay, 1986; Nachson

et al., 1995) suggest that the external features are more efficacious than the

internal features in forming discrimination judgments for unfamiliar faces, the

findings of other researchers (Ellis et al., 1979; Hines et al., 1987, Young et al.,

1985) are contradictory in that they found no reiiable difference in identification

rates for unfamiliar faces when participants were presented with the intemal or

external facial features. Nonetheless, participants in these studies were required to

make discrimination judgments of upright faces only. The results of the present

study make it clear that part-based decompositional strategies may result in a

reliance upon the internal rather than external features to form a discrimination

judgment for unfamiliar faces following inversion.

Participants in both Experiments 1 and 2 exhibited superior performance for

presentation of comparison faces consisting of both the intemal and external facial

features upon uprig ht sarne presentations, suggesting that the external features aid

in recognition performance for such unfamiliar faces. It is important to note,

however, that such performance may be related to holistic processing strategies

dictating attention to the entire face; no differences were observed in performance

for upright different comparison faces which may rely upon more part-based

processing mechanisms. When attention was focused on the intemal features at

study in Experiments 3 and 4, viewers exhibited superior performance for

comparison faces comprised of the intemal features alone upon both same and

different comparison presentations of upnght faces. The short conclusion is that

whereas the external features may aid in recognition performance for upright faces

when attention is focused upon the entire face and holistic processing strategies

are required (as for upright same judgments), the intemal features alone may be

sufficient to f o n a discrimination judgment when attention is focused upon these

features alone, in particular when part-based encoding strategies are required.

One alternative explanation for our findings is that format congruency

between test and comparison faces contributed to superior performance being

observed for comparison faces that shared the same features as those presented

at test (e.g., part face to part face). A recent series of experiments by Harman and

Moscovitch (in preparation) both replicated and extended the findings of other

researchers (e.g., Bruce, 1982; 1988; Farah et al., 1995; Patterson & Baddeley,

1977) in suggesting that format incongruency (i.e., differences in orientation or

form) between test and studied items may lead to subsequent detriments in

recognition performance. In Harman and Moscovitch's (in preparation) experiment,

participants were required to make an old-new judgment of faces and objects

presented either upright or inverted orfractured and whole. Half of the stimuli were

incongruent at study and test (e.g., whole to inverted) and the remaining half were

congruent (e.g., inverted to inverted). If congruence between study and test items

facilitates recognition, then items tested in a congruent format should exhibit

superior performance, regardless of whether they are presented upright or inverted

(or fractured or whole). Indeed, the results of the experiment indicated that facial-

recognition performance was best when the orientation of items at study matched

that at test, regardless of whether items presented were upright or inverted (or

fractured or whole). Recognition of objects, however, was best when test stimuli

were presented upright, regardless of study orientation.

In the present experiment, viewers exhibited superior performance for

comparison faces sharing the same facial features as those at test (e.g., part face to

part face). Nonetheless, such results were rnediated by processing strategies

associated with the recognition of upright (same and different) and inverted faces.

Specifically, viewers in Experiments 1 and 2 were presented with whole faces at

study; superior performance for whole faces was observed only upon upright same

presentations of cornparison faces that likely relied upon holistic or configurational

processing mechanisms. Indeed, superior performance was observed for part

faces following inverted comparison presentations in Experiment 2 perhaps

reflecting the contribution of part-based processing mechanisms mediated by the

object-recognition system. Study presentations in Experiments 3 and 4 involved

the intemal features only. With the exception of inverted different trials in

Experiment 3, superior performance was observed for part (interna1 features only)

rather than whole comparison trials, regardless of the orientation of comparison

stimuli or the mode of responding required; 2 reliance upon either holistic (upright

same faces) or part-based (upright different and inverted faces) processing

strategies could account for these findings. Because processing strategies (i.e.,

holistic or part-based) appear to supersede format congruencies between test and

cornparison items in detemining viewer performance, we suggest that a reliance

upon differential processing strategies for upright (same and different) and inverted

faces provides a better explanation of the current findings than does format

congruency.

Performance in several experimental conditions was relatively low. In

particular, viewers found it difficult to discriminate sequentially-presented inverted

cornparison faces, limiting the number of latency responses that were included in

the analysis of these conditions. Future research may incorporate testing

paradigms that provide for more accurate responding by viewers (e.g., longer

presentations of facial stimuli). In addition, although previous research suggests

that the object-recognition systern has preferential access to the external features

(Moscovitch et al., 1997) under conditions of inversion, the results of the present

study suggest that viewers may rely primarily upon the interna1 features to rnake a

discrimination judgment. Nonetheless, viewers were instructed to explicitly attend

to these features in forming their discrimination judgments. Future experimental

paradig ms rnay inco rporate different external features at study and test

presentations to determine more conclusively the role of the extemal features in

discrimination performance. In addition, other experiments, involving inverted

presentations of study faces may also be required to assess more carefully the

effects of part-based processing strategies ai initial study. Nonetheless, the results

of the present series of experirnents make it clear that viewers appear to rely upon

differential processing strategies in the recognition of upright (same and different)

and inverted faces. Moreover, in the present study attending to the intemal

features alone was sufficient to form a discrimination judgment for upright different

and al1 inverted faces; the same was true for upright same faces when attention

was focused on the intemal features alone at study. By contrast, viewers relied

upon both the intemal and external features to form a discrimination judgment for

upright same faces when attention was focused on the entire face at study.

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Table 1

Ex~eriment 1: Mean Accuracv bv Mode of Response and Taraet Format

Upright l nverted

Mode of - M - SD - n - M - SD - n Response

Same

Target Format

Part

Whole

Different

Target Fo m a t

Part

Whole

Table 2

Ex~eriment 1 : Mean Reaction Time bv Mode of Response and Taraet F o n a t

Upright 1 nverted

Mode of - M - SD - n - M - SD - n Response

Same

Target F o n a t

Part

Whole

Different

Target F o n a t

Part 1582.15 303.49 24 2056.13 640.22 24

Whole 1645.04 479.69 24 2023.52 850.76 24

Table 3

Experiment 2: Mean Accurac bv Mode of Response and Target Format

Upright l nverted

Mode of Response

Same

Target Format

Part

Whole

Different

Target Format

Part

Whole

Table 4

Exueriment 2: Mean Reaction Time bv Mode of Response and Taraet Format

Upright l nverted

Mode of - M SD - n Response

Same

Target Format

Part

Whole

Different

Target Format

Part

Whole

Table 5

Experiment 3: Mean Accuracv bv Mode of Response and Taraet Format

Upright

Mode of Response

Same

Target Format

Part

Whole

Different

Target Format

Part

Whole

Table 6

Experiment 3: Mean Reaction Time bv Mode of Res~onse and Taraet Format

Mode of Response

Same

Target Format

Part 1203.77 339.36 24

Whole 1893.10 814.03 24

Oifferent

Target Format

Part 954.06 309.32 24 2351.04 1193.64 24

Whole 1037.41 358.1 0 24 2443.56 1161 -44 24

Table 7

Ex~eriment 4: Mean Accuracv bv Mode of Response and Taraet Format

Upright lnverted

Mode of - M SD - n - M - SD - n Response

.. - -

Same

Target Format

Part

Whole

Different

Targ et Format

Part

Whole

Table 8

Experiment 4: Mean Reaction Time bv Mode of Response and Target Format

Upright 1 nve rted

Mode of Response

Same

Target Format

Part

Whole

Different

Target Format

Part 1063.83 262.13 24 1143.90 271.73 24

Whole 1213.48 414.53 24 1218.46 358.64 24

Fiaure 1. Examples of experimental conditions.

Condition 1: Upright whole face.

Condition 2: Upright part face.

Condition 3: lnverted whole face.

Condition 4: lnverted part face.

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