Neuropsycnologia. Vol., 18 pp. 85 to 87. C Pergamon Press Ltd. 1980. Prinled in Grear Britain.

0028-7932/80/0201-0085/SO2.00/0

NOTE

FACTORS AFFECTING THE SENSE OF FAMILIARITY WITH

CUE-ELICITED RESPONSES IN AMNESIC PATIENTS

GERALDINE OWEN and MOYRA WILLIAMS*

Department of Clinical Psychology, Cambridge Area Health Authority, Cambridge, U.K.

(Received 25 May 1979)

Abstract-An investigation was carried out into the parts played by basic target familiarity and cue-relevance on the sense of familiarity associated with cue-elicited responses in amnesic and senile patients. The amnesic subjects tended to accept as to-be-remembered targets any highly aroused items, but to the senile subjects the cues tended to act as distracters rather than as prompts.

IT HAS long been recognized that patients suffering from organic amnesia may alter their behaviour due to previous experiences despite being unable to recall the experience themselves. Claparede’s dramatic demon- stration of this phenomenon have been described by MCCURDY [I] while Bonhoeffer drew attention to it in some of the earliest descriptions of the organic amnesic states [2].

Such phenomena have come to be attributed to the absence of a sense of familiarity; but in laboratory situations where the selected target may be a word or picture, familiarity with the object as the to-be-remem- bered target has to be distinguished from its familiarity in the overall life situation due to frequency of past exposure or usage.

In normal subjects these two aspects to the sense of familiarity may be separate, but in Amnesic subjects they may be confused, for HUPPERT and PIERCY [3] have shown that on a recognition test using the yes/no procedure, Korsakov patients make more false as well as true positive responses to frequent than to rare items, due to a tendency to “say yes to familiar as opposed to unfamiliar items”. In other words, they may be taking as their criterion for target identity the arousal level of the stimulus only and ignoring (because they are unavailable?) any possible contextual anchors which identify it as target.

It is a characteristic of memory in both normal and amnesic subjects for recall to be facilitated by prompts or cues. However, in none of the experiments using prompts or cues with amnesic subjects has attention been paid to date to the effectiveness of the cues in arousing a sense of familiarity with the target as opposed to arousal of the target response.

To investigate this point, we conducted a group of experiments wherein both the familiarity of the target and the probability of the cue in arousing it could both be varied. In a preliminary pilot experiment with normal subjects the authors compared five different types of cue for their effectiveness in arousing both the name of the target and its recognition when this was presented either as a picture or a written word. These results were compared with the effectiveness of the cue in arousing the target name in a free association situation (“Guess what I am referring to”) when no target was seen.

It was found that the effectiveness of the cue as a prompt after target exposure was closely related to its effectiveness in arousing the object name in the free-association situation. The most effective cue was an incomplete sentence in which the target word was missing: the least effective was one referring to its category. These two types of cue were then used in a study of six amnesic subjects aged 55-65 and six patients suffering from senile dementia.

The number and proportion of correct responses in cued recall was compared with the number of correct (target) responses to the cue alone and showed the same relationship as in the control group: namely the more likely the cue was to elicit the target response in a free situation, the more likely it was to arouse a sense of familiarity with the target.

In senile subjects the difference between high and low probability cues was smaller, as the seniles tended to

*On a grant from the Mental Health Research Fund.

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respond to the cues as they would to distracters. For example, in response to the cue for the cart, “Put the horse before the. . .” one subject responded, “Oh yes, we had a lot of pictures of horses at home. I remember one quite well”.

Using only high-probability cues, we than examined the sense of familiarity following cued recall of rare as opposed to common objects, following HUPPERT and PIERCY’S [3] suggestion that in amnesics basic familiarity played an important part in determining target familiarity.

Eight pictures of common objects (name-frequency in the Thorndike/Lorge Word Count [4] over 100 per million) and eight rare objects (name-frequency less than 10 per million) were drawn on cards, and for each object a cue was prepared consisting of a sentence in which the target word (replaced by a blank) had a 90 % probability of occurrence.

The subjects were shown four of the common objects and four of the rare ones, and after 10 min were asked how many pictures they could remember. For each picture not recalled, and for the eight pictures which had not been shown to them, they were then given the appropriate cue and were asked after each response to say whether they remembered seeing a picture of the named object.

The results shown in Table 1 were evaluated to indicate the extent to which ability to discriminate between target and non-target picture-names was affected by the frequency of that name (PLACKETT, [5] p. 88). For the controls and the seniles the mean effect was nonsignificant (I = 0.007 and I = 0.375 respectively); but for the amnesics the effect was significant (z = 1.97, P < 0.025 one-tailed) and indicated that the sense of familiarity was related to the frequency of past usage-what might be called its “basic arousal level”.

In a further experiment an attempt was made to see whether the basic arousal level of a word in amnesics could be affected as it is in normals by associational spread from synonyms and homonyms (Light [6]). The results, however, indicated considerable variability among amnesic subjects in this respect.

Table 1.

Subjects Free recall

No storable response

Correct “Yes”

Correct “no”

Incorrect “Yes”

Incorrect “no” Total

Control rare 9 7 13 16 2 1 48 (N = 6) common 8 2 15 19 3 1 48 Amnesic rare 2 6 20 13 6 1 48 (N = 6) common 2 0 16 11 13 6 48 Senile rare 5 II 14 17 0 1 (N = 6) common 7 1 15 21 3 1 ::

CONCLUSION It seems that amnesic patients do tend to judge the familiarity of a cue-evoked response on the strength

with which it is aroused, this being due partly to its basic arousal level (due to past usage) and partly to the intensity of its arousal by the cue. Whereas normal subjects usually tend to seek additional evidence for target familiarity in the recall of contextual events, amnesics seem to lack the ability to summon this support and have to make their judgements without it.

Acknowledgements-We would like to express our thanks to the Mental Health Research Fund for financial support, and the Consultants and Staff in the Cambridge Area Health Authority and Dr. Dennis Leigh of the Maudsley Hospital for permission to study the patients under their care.

We would also like to thank the staff at the MRC Applied Psychology Unit in Cambridge for assistance especially Dr. I. Nimmo-Smith for his statistical analysis of the data.

REFERENCES 1. 2. 3. 4.

MCCLJRDY, J. T. Common Principles in Psychology and Physiology. University Press, Cambridge, 1928. BONHOEFFER, K. Die akuren Geisteskrankheiten der Gewdhnkeitstrinker. Jena, 1901. HUPPERT, F. and PIERCY, M. Recognition memory in amnesic patients. Cortex 12, 8. 1976. THORNDIKE, E. L. and LORGE, I. The Teachers Word Book of3O,OOO Words. Teacher’s College, Columbia University, NT, 1944.

5. PLACKETT, R. L. The Analysis of Categorical Data. Griffin, London, 1974. 6. LIGHT, L. L. Homonyms and synonyms as retrieval cues. J. exp. Psychof. 96,255, 1972.

NOTE 87

On a recherche cher des malades amnesiques et s6niles

le r6le joue par la familiarit@ de la cible et par la pertinence par

rapport a la cible au sens de la familiar-it6 associee aux reponses

6voquees par l’indice. Les sujets amnLsiques tend&e& a accepter comme

cible devant &tre rem&aoris~e tout item frequexmuent evoque tandis que

chez les sujets seniles, les reperes tendaient a agir comme distrac-

teurs plutCit qu’a entrainer les reponses.

Zusammenfassung r

Bei Amnestischen und Patienten mit seniler Demenz wurde untersucht,

welche Rolle die allpemeine Bekanntheit und welche spezielle Anhalts-

punk’te fiir das Eintreten eines Gefiihls der Vertrautheit haben. Die

amnestischen Patienten nelgten dasu, jede Art van stark stimulierenden

Items als Material der Merkaufpabe su akseptleren, wahrend die speziellen

Hinweise bei senil-dementen Patienten cher als Ablenker wirkten.