1. Impoverished faces evoke activity in the ventral visual stream.2. Spatial selectivity is limited, but an inversion effect is still present.3. Face classification is impaired by object primes.

INTRODUCTIONPrevious electrophysiological, neuroimaging, and lesion studies

have demonstrated that regions within the fusiform gyrus show selective activity to images of faces compared to other stimuli (Kanwisher et al., 1997; McCarthy et. al, 1997). In the present studies, we explore whether greatly impoverished face stimuli evoke activity within these regions and how the processing of impoverished face stimuli is influenced by prior stimulus context.

In Experiment 1, we presented line drawings of faces (Brunswik& Rieter, 1938) and objects while measuring changes in brain activity using fMRI at 4T. We investigated whether such simple faces reliably activated ventral visual regions, whether activity depended upon the orientation of the stimulus, and whether face selective regions showed selectivity for impoverished faces. Previous results havesuggested that specificity is greatly reduced to such simple stimuli (Peters et al., 2000).

In Experiment 2, we examined the influence of irrelevant priming information upon behavioral responses to these faces in a simplediscrimination task. We evaluated whether processing of these simple faces can be influenced by the characteristics of a priming stimulus, and whether priming effects depended upon the hemisphere of processing.

Experiment 1: fMRI• Participants: 10 young adults (18-26y)• Screening Task:

• Alternating blocks of photographs of objects and faces• 8s of objects, 8s of faces/objects• 4 runs of 3:42min

• Experimental Task:• Upright & inverted face drawings (Brunswik & Rieter, 1938)• Line drawings of objects (courtesy of Michael J. Tarr, BrownUniversity, Providence, RI)

• Stimuli presented for 200ms, with 12-16s ISI• 9 runs of 6:14min

• fMRI data acquisition at 4T:• BOLD contrast T2*-weighted spiral-in pulse sequence• TR, 1500ms; TE, 31ms; flip angle, 80�• Voxel size: 3.75*3.75*3.8mm• 34 axial slices parallel to AC-PC line

• Preprocessing and analysis:• Correction for head motion & slice timing, spatial smoothing (6mm FWHM), and spatial normalization using SPM99.• Screening task: Fourier analysis used to identify voxels whose activity followed task frequency and phase. Regions of interest were defined in ventral occipito-temporal cortex.• To evaluate functional selectivity, the raw functional signal was time-locked to stimulus onset, and averaged epochs were calculated for the screening-task ROIs. • To evaluate the inversion effect, voxels active to any stimulus were identified using correlation analyses of the experimental task data and random-effects analyses across subjects. The mean amplitude to upright and inverted faces was calculated in these functionally-defined ROIs.

Experiment 2: Behavior•Participants: 10 young adults (20-28y)•Task:

• At the beginning of each trial, an arrow (2000ms) cued subjects to attend to the left or right side of the display. • Following a 500ms delay, one of three priming stimuli was presented on the uncued side for 100ms: a blank screen (no prime), a scrambled set of lines, or an object line drawing. • At the offset of the priming stimulus, a face or an object appeared on the cued side of the display for 100ms.• The participant pressed the left button if the cued stimulus was a face, or the right button if it was an object.• 630 trials: 462 of face targets, 168 of object targets.• 7 runs of 6:03min

METHODS

Lisa H. Berghorst1,6, Scott A. Huettel1,2,3,4, & Gregory McCarthy1,3,4,5

1Brain Imaging and Analysis Center; Departments of 2Psychiatry, 3Neurobiology, and 4Radiology, Duke University Medical Center;Department of 5Psychology, Duke University; 6Trinity College, Duke University.

author contact: scott.huettel@duke.edu

References:• Brunswik, E. & L. Rieter. (1938). Eindruckscharaktere schematisierter Gesichter. Zeitschrift Fuer

Psychologie, 142: 67-134.

• Kanwisher, N., J. McDermott, & M. M. Chun. (1997). The fusiform face area: A module in human extrastriate cortex specialized for face perception. J Neuroscience, 17: 302-11.

• McCarthy, G., A. Puce, J. C. Gore, & T. Allison. (1997). Face-specific processing in the human fusiform gyrus. J Cognitive Neurosci, 9(5): 605-10.

• Peters, R. J., F. Gabbiani, J. Jovicih, & C. Koch. (2000). Models of visual object representation in humans. J Cognitive Neurosci, 0:72.

• Simon, J. R., & A. M. Small Jr. (1969). Processing auditory information: interference from an irrelevant cue. J Applied Psychology, 53: 433-5.

CONCLUSIONS

Do impoverished faces evoke activity in the ventral visual stream?Experiment 2: Behavior

Do visual primes influence processing of impoverished face stimuli?

Does the influence of irrelevant visual information depend upon the hemifield of face presentation?

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Do face- and object-selective regions show selectivity for impoverished stimuli?

Is there a face inversion effect?

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Yes, schematic faces evoked activity in similar regions as schematic objects.

Yes, an inversion effect was found for both hemispheres.

Although similar regions were active to faces and objects,

there was a significant interaction between region and

stimulus type.

Yes, both scrambled and object primes appeared to slow responses to faces.

Objects

Faces & Objects

4. Priming effects are only present for right hemifield faces.5. A right-hemisphere face module may resist influence of

irrelevant object information from the left hemisphere.

Yes, priming effects were only found for faces presented to the right hemifield. The observed main effect of hemifield across all conditions may reflect faster processing by the

right hemisphere or may be due to a Simon effect.

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