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Impairment in Facial Recognition in Patients with Cerebral Disease
IMPAIRMENT IN FACIAL RECOGNITION IN PATIENTS WITH CEREBRAL DISEASE I
A. L. Benton and M. W. Van Allen (Neurosensory Center and Departments of Neurology and Psychology, University of Iowa)
INTRODUCTION
Prosopagnosia, or specific impairment in recognizing familiar faces, is a relatively uncommon complaint in patients with cerebral disease. Nevertheless, since it was first noted by Charcot and Wilbrandt, the phenomenon has been the subject of numerous case reports, as well as of one large scale study. The features of the disability are well described by Hecaen and Angelergues (1962) who have reported the only study of a relatively large group of cases. The primary disorder is the incapacity of the patient to identify persons on the basis of visual perception of their faces. Recognition is accomplished on the basis of perception of stature, clothes, gait or voice or by noting such accessories as eye glasses or cigarette holders. Faces are recognized as such and, in most cases, the patient is able to distinguish between the face of a man and that of a woman. The patient may be able to give an adequate general description of the face which he perceives but at the same time be unable to identify the person. However, some patients show features of metamorphopsia in that faces appear to them to be grossly distorted. Defective recognition of well-known public figures and of symbols (e.g., Red Cross, swastika) is also frequent in these patients. The disability has been reported to have some rather distinctive correlates. Visual memory, particularly for spatial relationships, is commonly impaired. Defects in the left visual half-field, constructional I This investigation was supported by Program-Project Grant NB-03354 and Research Grant NB-00616 from the National Institute of Neurological Diseases, Neurosensory Center Publication No. 153.
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apraxia and dyspraxia for dressing have been noted as being frequent accompaniments. However, global mental impairment mayor may not be present; some patients are quite intact intellectually and evidently capable of pursuing a high-level occupation. In general, as Hecaen and Angelergues have emphasized, the disability is associated with the constellation of behavioral deficits associated with lesions of the right hemisphere. Because facial agnosia is an uncommon symptom, direct evidence concerning its relationship to locus of cerebral lesion is meagre. Bilateral occipital lesions have been described in some cases and hence certain authors have been inclined to believe that bilateral disease is a necessary antecedent condition for the appearence of the deficit. On the other hand, Hecaen and Angelergues inferred from their material of 22 cases that lesions of the right hemisphere were present in 16 cases, lesions of the left hemisphere in 2 cases and bilateral lesions in 4 cases. They therefore concluded that the occurrence of facial agnosia is contingent upon the presence of a lesion of the right hemisphere. For the most part, the occipital lobes (but not necessarily the striate area) appear to be the site of primary involvement. The basic nature of the disorder has been a topic of some speculation. It has been thought to be the product of an interaction between a more generalized visual agnosia and a disturbance of the body schema (Hoff and Potzl, 1937; Potzl, 1953). In this regard, it may be noted that one or another type of visuoperceptive impairment (e.g., faulty identification of objects, colors, pictures or symbols and spatial disorientation) is often seen in association with facial agnosia. Other explanations have emphasized either sensory or higher-level perceptual deficits without invoking a disorder of the body schema. Thus Bay (1953), in harmony with his general position regarding the nature of agnosic disturbances, contended that facial agnosia is the expression of a primary sensory impairment that prevents simultaneous recognition of the several parts of a face so that it cannot be recognized as a distinctive global unity. The fact that patients with facial agnosia do in fact very often show primary sensory impairment, particularly visual field defects, supports Bay's conception. However, the equally evident fact that most patients with similar impairment of equal and even greater severity do not show this peculiar deficit can only weaken the cogency of his hypothesis. Moreover, there is also the consideration that the recognition of a face often follows a momentary glimpse of a single part of it and simultaneous recognition of a number of parts
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does not seem to be a necessary precondition for recognition. Faust (1947, 1955) has advanced the concept that facial agnosia represents a disorder in which the patient fails to grasp the detailed features of a complete stimulus situation so that its individuality is not identified. It follows from this that a patient suffering from impairment in the recognition of faces also should have difficulty in discriminating other types of stimuli as well and indeed Faust has described a single patient who could not distinguish between an ordinary chair and an armchair and whose recognition of visual stimuli under conditions of tachistoscopic presentation was defective. It is difficult to validate conceptions such as those of Bay and of Faust because the opportunity to study this uncommon complaint so rarely presents itself. On the other hand, if facial agnosia is a true neurological disability and not the product of psychodynamic factors (as some clinicians suspect), it is reasonable to expect that the basic impairment underlying it should be shown in less flagrant form by a larger number of patients with cerebral disease and that it should be possible to bring this impairment to light by appropriate methods of study. This consideration provided the impetus for the present investigation as weIl as for the recent studies of De Renzi and Spinnler (1966), De Renzi, Faglioni and Spinnler (1968) and Warrington and James (1967), in which the ability to recognize or remember faces was quantitatively assessed under controIled conditions of presentation. De Renzi and Spinnler (1966) investigated the performances of patients with hemispherically localized cerebral lesions on tasks involving immediate memory for photographs of faces, chairs and abstract line drawings. They found that the patients with right hemisphere disease performed on an inferior level to those with left hemisphere disease on the face and abstract drawing tests but not on the chair test. Moreover, while performances on the face and abstract drawing tests were positively intercorrelated in both groups of patients, the chair test was not correlated with either of the other two tasks. Visual field defects were associated with poor performance in the right hemisphere group but not in the left hemisphere group. Presence of aphasic disorder was not related to performance level. De Renzi and SpinnIer contend that their results provided no support for Faust's conception that facial agnosia is ascribable to a specific incapacity for identifying the "individuality" of a stimulus-complex. Instead they concluded that the deficit probably represents an impairment in visual discrimination and integration.
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A subsequent study by De Renzi, Faglioni and Spinnler (1968) confirmed these findings of a hemispheric difference in performance and of a relationship between visual field defect and inferior performance in patients with right hemisphere lesions but not in those with left hemisphere lesions. Warrington and James (1967) similarly investigated immediate memory for faces but, in addition, also assessed the recognition of the faces of well-known public figures (e.g., Winston Churchill, President Kennedy) in patients with right and left hemisphere disease. They found that the patients with lesions of the right hemisphere performed on an inferior level on both tests. However, there was no correlation between scores on the two tests in either group, indicating the absence of a common factor in the two types of performance. In view of this lack of correlation and the fact that facial agnosia appears to be primarily an impairment in recognizing familiar faces, Warrington and James express doubt that tests of the ability to recognize unfamiliar faces are relevant to the problem of facial agnosia. We have investigated this question of impairment of facial recognition in patients with cerebral disease in a somewhat different manner. A matching procedure, which makes no demands upon immediate memory, has been employed. The tasks presented to the subject have involved not only matching identical photographs of an unfamiliar face but also matching different photographs of the same face. MATERIALS AND METHODS
Materials and procedure
Photographs (2 in. X 2 in.) of front, three-quarter and profile views of draped subjects were taken under varied lighting conditions. As a result of pilot testing, a selection of these photograph was made and a test of facial recognition calling for 54 responses was developed. The test consists of 3 parts: A - Matching of identical front-view photographs (Figure 1A); the subject is presented with a single front-view photograph of a face and instructed to identify it (by pointing to it or calling its number) in a display of 6 front-view photographs placed at the right of the single photograph; 3 male and 3 female faces are presented for matching, calling for a total of 6 responses.
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B - Matching of front-view with three-quarter-view photographs (Figure 1B); the subject is presented with a single front-view photograph of a face and instructed to locate it 3 times in a display of 6 three-quarter-views, 3 being of the presented face and 3 being of other faces; 4 male and 4 female faces are presented for matching, calling for a total of 24 responses. C - Matching of front-view photographs under different lighting conditions (Figure 1C); the subject is presented with a single frontview photograph of a face taken under full lighting conditions and instructed to locate it 3 times in a display of 6 front views taken under different lighting conditions; 3 photographs are of the presented face and 3 are of other faces; 4 male and 4 female faces are presented for matching, calling for a total of 24 responses. Thus the test calls for 54 scorable responses. Since the probability of chance success is 1 in 6 in Part A and 1 in 2 in Part Band C, a score of 25 may be expected on the basis of chance alone. Hence the effective range of scores may be considered to be 25-54. Subjects
The test was given to 111 patients without obvious evidence or history of cerebral disease who were seen on the neurological, neurosurgical and medical services of the University Hospitals, Iowa City. Range of ages in this control group was 16-65 years and educational level ranged from 6 to 16 years. Twenty-two patients with lesions apparently confined to the left hemisphere and 15 patients with lesions apparently confined to the right hemisphere were given the test. Range of ages in the left hemisphere group was 19-63 years and educational level ranged from 5 to 16 years. In the right hemisphere group, range of ages was 16-60 years and' educational level ranged from 7 to 16 years. The status of the patients in the two groups with respect to type of lesion is outlined in Table 1. It will be noted that cerebrovascular disease was the most frequent diagnosis in the left hemisphere group; in contrast, intrinsic neoplasm was the most frequent diagnosis in the right hemisphere group.
A
•
II
•
•
II.
•
•
•
B
•
•
•
II.
•
•
•
c
f
~
•
•
i
•
•
Fig. 1 - A: test item calling for matching of identical front views; B: test item calling for matching of frontal view with threeLjuarter views; C: test item calling for matching of frontal views under different lighting conditions.
II.
•
•
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TABLE I
Classification of Cases with Respect to Type of Lesion
Left hemisphere cases
Vascular Neoplasm Trauma Atrophy
Right hemisphere cases
= 15)
(N =22)
(N
16 (73%) 4 (18%)
5 (33%) 8*(52%) 1 (7%) 1 (7%)
2 (9%)
* Intrinsic neoplasm (7); Meningeoma (1).
RESULTS
Normative observations
The total sample of 111 control patients was divided into subsamples according to age, sex and educational level in order to assess the influence of these factors on performance level (Table II). InspecTABLE II
Mean Scores of Control Subgroups Age range: 16-50 years Males with 12 + years of education (N = 24) Males with < 12 years of education (N 9) 33) Females with 12 + years of education (N Females with < 12 years of education (N = 26)
= =
Mean 46.5 46.7 46.2 44.8
Range 36-53 43-51 35-54 37-50
42.9 41.6
39-52 38-51
Older age groups 51-60 years (all subjects N = 12) 61-70 years (all subjects N = 7)
tion of data for patients under the age of 51 indicates no important differences attributable to sex or educational level. As will be seen, the normative date for older subjects are quite meagre. They suggest a moderate decline in performance level with increasing age. However, it will be noted that the range of scores in the older age groups is not wider than in the younger groups and that the lowest scores were
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in fact made by some younger subjects. With these considerations in mind, it was felt that, for the purposes of the present study, it was justifiable to combine the subsamples into a single total sample of control patients. In Table III are shown the mean scores of this TABLE III
Mean Scores
Left hemisphere
Control (SD
Right hemisphere
42.5 (SD = 5.0)
45.3
= 4.5)
(SD
34.7
= 6.4)
Differences Control vs. Left Control vs. Right Right vs. Left
2.8 (t = 2.67; p 10.6 (t = 8.04; p 7.8 (t = 4.00; p
< .01) < .001) < .001)
sample and in Table IV are shown the distributions of the individual scores. TABLE IV
Distributions of Scores Right
Score
Control
Left
52-54 49-51 46-48 43-45 40-42 37-39
7 25 25 25 17 9
2 4 6 4 3
3
34-36
3
2
4
1
31-33 28-30 25-27
1
1
3
2
111
22
15
Performances of patients with cerebral disease
The mean scores of the two groups of patients with cerebral disease are shown in Table III. It will be seen that the overall performance levels of both groups are significantly lower than that of the control patients. However, it will also be noted that the mean score
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of the patients with right hemisphere disease is significantly lower than that of the -patients with left hemisphere disease. Table IV shows the distributions of the individual scores of the brain-damaged groups in comparison to that of the control patients. The fact that a significant proportion of patients with right hemisphere lesions made grossly inferior performance is quite clear. As will be seen, the scores of 6 (40 per cent) of these 15 patients were below that of the poorest control patients, while this was true of only 1 (4.5 per cent) of the patients with left hemisphere disease. If a score of 36 or less (i.e., a score exceeded by more than 97 per cent of the controls) is adopted as a criterion of defective performance, a majority (66.7 per cent) of the patients with right hemisphere disease would be classified as impaired, as compared to 3 (13.6 per cent) of the patients with left hemisphere disease. Performance level and visual field defect
Visual field defects were demonstrated in 8 of the 15 patients with right hemisphere disease and in 7 of the 22 patients with left hemisphere disease. The mean performance levels of the patients with and without visual field defects in the two groups are shown in Table V. TABLE V
Visual Field Defects and Performance Level
Right hemisphere cases Field defect (N
= 8)
Mean score = 35.5 Range of scores: 28-50
Field defect (N
= 7)
Mean score = 41.4 Range of scores: 35-51
No field defect (N
= 7)
Mean score = 33.9 Range of scores: 26-44 Left hemisphere cases No field defect (N
= 15)
Mean score = 42.9 Range of scores: 31-50
It is evident from inspection of this table that performance level was not related to the presence of visual field defect in either group of patients.
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Performance level mid aphasia
Ten of the 22 patients with left hemisphere disease were clinically aphasic in the sense that they showed manifest disturbances in expressive language. In some cases, language understanding was also clearly impaired; in the other cases, impairment in language comprehension, if present, was minimal. The mean performance levels of the aphasic and non-aphasic patients are presented in Table VI. No relationship between performance on the test of facial recognition and the presence of clinically manifest aphasic disorder is shown. TABLE VI
Aphasia and Performance Level
Left hemisphere cases Aphasic (N
= 10)
Not aphasic (N
Mean score
=
Mean score = 42.6
42.3
Range of scores: 35·48
With VFD (N Mean score
= 2)
= 41.0
Without VFD (N Mean score
= 8)
= 42.6
= 12)
Range of scores: 31-51
With VFD (N Mean score
= 5)
= 42.6
Without VFD (N Mean score
= 7)
= 42.6
Performance level and intrahemispheric locus of lesion
It was possible to specify the primary site of pathologic involvement in 13 of the 15 cases of right hemisphere disease and in 13 of the 22 cases of left hemisphere disease. The performance levels of subgroups of patients classified according to intrahemispheric locus of lesion are shown in Table VII. No systematic trends are apparent. It will be noted particularly that in both hemispheric groups the performance levels of the patients with lesions apparently confined to the frontal lobes are not higher than those of the patients with lesions of the parieto-occipital area.
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TABLE VII
Locus of Lesion and Performance Level
Mean scores Right hemisphere
Left hemisphere
Frontal
(4) 33_8
(3) 38.7
Temporal Temporo-parietal Temporo-occipital
(2) 42.5
(3) 46.0
Parietal Parieto-occipital Fronto-parietal
(7) 35.0
(7) 42.9
Undetermined
(2) 28.0
(9) 42.2
Performance level and type of lesion
Since the two hemispheric groups were not comparable in respect to the relative frequency of different types of lesions, an analysis of the relationship between performance level and type of lesion was made. The findings are shown in Table VIII. It will be noted that, in the right hemisphere group, the performance of the intrinsic neoplasm subgroup is not inferior to the vascular subgroup. Grossly
TABLE VIII
Type of Lesion and Performance Level
Right hemisphere cases (Mean scores) Neoplastic (N = 8)* Vascular (N = 5) Traumatic (N = 1) Atrophic (N = 1)
34.8
31.2
50 35
Left hemisphere cases (Mean scores) Neoplastic (N = 4) Vascular (N = 16) Atrophic (N = 2)
42.0
43 .1 38.0
* Intrinsic neoplasm (7), Mean score = 35.7; Meningeoma (1), Score = 28.
defective performances (i.e., scores of less than 34) were made by 2 (29 per cent) of the 7 patients with intrinsic neoplasm but also by 3 (60 per cent) of the 5 patients with vascular disease.
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DISCUSSION
Our results clearly indicate that impairment in facial recognition, as assessed by the task presented to our patients, is closely associated with disease of the right hemisphere. The patients with right hemisphere lesions performed on a significantly lower level than those with left hemisphere disease. Moreover, the most grossly defective performances were made practically only by patients with disease of the right hemisphere. The observed differences between the two unilateral groups cannot be ascribed to such factors as presence or absence of of visual field defect, type of lesion or intrahemispheric locus of lesion. In comparative clinical studies of the type exemplified by the present investigation, the factor of size of lesion usuany remains an uncontrolled variable . This circumstance poses a problem in interpretation if there is reason to suspect inequality with respect to size of lesion in the two hemispheric groups. There are considerations which raise the question of whether random selection of patients on a neurological or neurosurgical service may not tend to result in the formation of a sample of patients with right hemisphere lesions of unlimited extent as compared to a sample of patients with left hemisphere lesions of limited extent. For example, it seems possible that, because of the more handicapping effects of left hemisphere lesions in general (language disturbance, impairment of the preferred hand), patients with such lesions will be seen for study and treatment at an earlier, less advanced stage of disease than patients with lesions of the right hemisphere. Moreover, an extensive lesion of the left hemisphere may render a patient so severely aphasic that he cannot be made to understand test instructions and he is therefore excluded from a study. This is not likely to happen in the case of patients with extensive lesions of the right hemisphere who typically retain a fair degree of language understanding. However, a number of observations make it seem unlikely that the variable of size of lesion was a significant determinant of the interhemispheric difference in performance found in the present study. First, there is the finding that the aphasic patients with left hemisphere lesions did not perform more poorly than the non-aphasic patients with left hemisphere lesions. We have no direct evidence that these two subgroups differed in respect to extent of lesion. However, it may be presumed that by definition the non-aphasic patients had
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lesions of limited extent in the sense that the language zone was not compromised and that this limitation does not apply to the aphasic patients. Yet no difference in performance level was observed. Secondly, there is the consideration that patients with lesions confined to one or the other frontal lobe did not differ in performance from their counterparts with post-Rolandic lesions. This was particularly noteworthy in the case of patients with right frontal lesions who showed as high a frequency of failure as those with right parieto-occipital lesions. Thirdly, patients with infiltrating neoplasms of the right hemisphere, some of which probably extended into neighboring areas, did not perform at a lower level than patients with other types of lesions in the right hemisphere. Finally, inspection of the individual cases discloses instances of defective performance on the part of some patients with right hemisphere lesions of apparently rather limited extent. The relationship of the findings to the symptom of "facial agnosia" remains problematical. No patient in the study spontaneously complained of inability to recognize familiar faces. The finding in this study and those of De Renzi and Spinnler (1966) and of Warrington and James (1967) of right hemisphere "dominance" for performance on facial recognition tasks is in consonance with the generalization that facial agnosia is preeminently a complaint of patients with disease of the right hemisphere. On the other hand, as Warrington and James have pointed out, facial agnosia involves loss of recognition of familiar faces, an operation which presumably involves memory processes, and indeed they speculate as to whether the symptom may not represent a partial form of the amnesic syndrome. In any case, since defective discrimination of unfamiliar faces appears to be specifically associated with right hemisphere disease, it is of interest in its own right, independently of its possible relationship to the clinical complaint of facial agnosia. The question then arises as to the nature of the basic impairment underlying this performance deficit. Do patients who fail this task suffer from significant visual impairment so that they do not receive the basic sensory information required to effect the discrimination? Parenthetically, it may be noted that this question in more general form has been raised about other forms of "agnosia" as well, e.g., visual object agnosia, visuospatial agnosia, tactile agnosia (Bay, 1953; Bender and Feldman, 1965). All the patients in our study appeared to have adequate visual acuity, as judged from notations in the case records. However, a standard
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assessment of visual acuity was not done as part of the study and it would be of interest to explore the influence of this as well as other visuosensory factors on performance level. De Renzi and Spinnler found an association between inferior performance and visual field defect in their patients with right hemisphere disease but not in those with left hemisphere lesions. As has been noted, our own findings were quite negative in this respect . In summary, it does not appear that one deals here with a performance deficit which is explainable in terms of simple sensory impairment. General mental impairment also needs to be considered as a possible determinant of defective performance. In a critique of the concept of agnosia, Bender and Feldman (1965) have advanced the hypothesis that the performance deficits which are placed in this category are the product of a combination in varying degrees of sensory impairment and general mental impairment. Applying this idea to defective facial discrimination, it may be asked whether the deficit is not simply a partial expression of general behavioral incompetence. Our observations do not support the idea. Of the different subgroups, one would expect that the aphasic patients would be most impaired intellectually. However, as has been shown, not only were these patients not inferior to non-aphasic patients with left hemisphere disease but they were decidedly superior to those with right hemisphere lesions. It will be recalled that De Renzi and Spinnler (1966) also found no evidence for an association between aphasia and defective facial recognition. It was not possible to evaluate the concept of Bender and Feldman that a combination of general intellectual impairment and basic sensory deficit is responsible for the appearance of agnosic phenomena since only two aphasic patients showed visual field defects. One of these made a poor performance but the other made a relatively good score on the test of facial discrimination. It may also be observed that the one patient in the left hemisphere group who made a grossly defective performance was not aphasic, showed no visual field defects and was noted as having 20/20 vision bilaterally. Thus it seems likely that "higher-level" visuoperceptive deficit, i.e. , impairment in the integration of received sensory data, underlies failure in facial discrimination. If this is so, it should be possible to disclose evidence of this basic impairment in other task performances. De Renzi and Spinnler (1966) found a significant positive correlation between performance level on tasks involving immediate memory for
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faces and immediate memory for abstract line drawings in both patients with right hemisphere and with left hemisphere disease. They therefore concluded that a more generalized impairment in visual discrimination underlies defective facial recognition. In an investigation of the relationship between facial recognition and various other task performances in mental defectives, Benton and Gordon (1964) found that performance on a test involving the discrimination of patterns of brightness correlated most closely with performance on the facial recognition test. The possible implications of this finding deserve further exploration, particularly in patients with focal cerebral disease. Empirical observations to date are not sufficient to provide the basis for a precise definition of the disability underlying defective facial recognition. However, two facts seem to be reasonably clear. First, the disability is shown with greater frequency and in more severe form by patients with lesions of the right hemisphere; hence, by inference, it would appear that the right hemisphere plays a special role in the mediation of this ability. Secondly, the weight of evidence suggests that the disability involves faulty integration and discrimination of sensory data rather than simple sensory deficit. Thus defective facial recognition takes its place among those types of performances which have been found to be particularly severely impaired as a consequence of disease of the right hemisphere. The nature of the basic functions or abilities underlying these performances remains an unanswered question. SUMMARY
A test requiring the identification of unfamiliar faces was developed and given to groups of patients with lesions of the left or the right hemisphere as well as to a large group of control patients. Performance level in the control group showed a slight decline with age but was not related to education or sex. The mean performance levels of both brain-damaged groups were significantly inferior to that of the control group. In addition, however, the mean performance level of the patients with right hemisphere lesions was significantly inferior to that of the patients with left hemisphere lesions and grossly defective performances were made mainly by patients with right hemisphere lesions. Performance level was not related to the presence of visual field defect, the presence of aphasia, type of lesion or intrahemispheric locus of lesion. A number of considerations suggested that the observed interhemispheric difference in performance
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was not related to a possible difference in the extent of lesion in the two groups. The observations clearly indicate that impairment in facial recognition, as assessed by the procedures utilized in the study, is rather closely associated with disease of the right hemisphere. The relationship of the findings to the clinical complaint of prosopagnosia and the nature of the basic disabilities underlying defective facial recognition are considered. Acknowledgment. We are indebted to Dr. Musetta Gordon for her aid in developing the test materials and in conducting the pilot study which preceded the present investigation. REFERENCES BAY, E. (1953) Disturbances of visual perception and their examination, "Brain," 76,
515-550. BENDER, M. B., and FELDMAN, M. (1965) The so-called visual agnosias, Proc. 8th Internat. Congo NeuroL, 3, 153-156. BENTON, A. L., and GORDON, M. C. (1964) Aspects of facial recognition:n mental deficiency, Paper presented at Meeting of American Association on Mental Deficiency, Omaha . DE RENZI, E., FAGLIONI, P ., and SPINNLER, R . (1968) The performance of patients with unilateral brain damage on face recognition tasks, "Cortex," 4, 17-34. - , and SPINNLER, H. (1966) Facial recognition in brain-damaged patients, "Neurology," 16, 145-152. FAUST, (1947) Partielle Seelenblindheit nach Occipitalhirnverletzung mit besonderer Beeintriichtigung des Physiognomieerkennens, "Nervenarzt," 18, 294-297. (1955) Die Zerebrale Herdstorungen bei Hinterhauptsverletzungen und ihre Beurteilung, Georg Thieme Verlag, Stuttgart. HtCAEN, H., and ANGELERGUES , R. (1962) Agnosia for faces (prosopagnosia), "Arch. NeuroL," 7, 92-100. HOFF, R., and POTZL, O. (1937) Ober eine optisch-agnostische Storung des "Physiognomie-Gedachtnisses" (Beziehung zur Riickbildung eines Wortblindheit) , "Ztschr. NeuroL Psychiat.," 159, 367-395. POTZL, O. (1953) Zur Agnosie des Physiognomiegedachtnisses, "Wiener Ztschr. Nervenheilk.," 6, 335-354. WARRINGTON, E. K., and JAMES, M. (1967) An experimental investigation of facial recognition in patients with unilateral cerebral lesions, "Cortex," 3, 317-326.
c.
Prof. A. L. Benton, Department of Neurology, University Hospital, Iowa City, Iowa 52240 (U.S.A.).
A. L. Benton and M. W. Van Allen (Neurosensory Center and Departments of Neurology and Psychology, University of Iowa)
INTRODUCTION
Prosopagnosia, or specific impairment in recognizing familiar faces, is a relatively uncommon complaint in patients with cerebral disease. Nevertheless, since it was first noted by Charcot and Wilbrandt, the phenomenon has been the subject of numerous case reports, as well as of one large scale study. The features of the disability are well described by Hecaen and Angelergues (1962) who have reported the only study of a relatively large group of cases. The primary disorder is the incapacity of the patient to identify persons on the basis of visual perception of their faces. Recognition is accomplished on the basis of perception of stature, clothes, gait or voice or by noting such accessories as eye glasses or cigarette holders. Faces are recognized as such and, in most cases, the patient is able to distinguish between the face of a man and that of a woman. The patient may be able to give an adequate general description of the face which he perceives but at the same time be unable to identify the person. However, some patients show features of metamorphopsia in that faces appear to them to be grossly distorted. Defective recognition of well-known public figures and of symbols (e.g., Red Cross, swastika) is also frequent in these patients. The disability has been reported to have some rather distinctive correlates. Visual memory, particularly for spatial relationships, is commonly impaired. Defects in the left visual half-field, constructional I This investigation was supported by Program-Project Grant NB-03354 and Research Grant NB-00616 from the National Institute of Neurological Diseases, Neurosensory Center Publication No. 153.
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apraxia and dyspraxia for dressing have been noted as being frequent accompaniments. However, global mental impairment mayor may not be present; some patients are quite intact intellectually and evidently capable of pursuing a high-level occupation. In general, as Hecaen and Angelergues have emphasized, the disability is associated with the constellation of behavioral deficits associated with lesions of the right hemisphere. Because facial agnosia is an uncommon symptom, direct evidence concerning its relationship to locus of cerebral lesion is meagre. Bilateral occipital lesions have been described in some cases and hence certain authors have been inclined to believe that bilateral disease is a necessary antecedent condition for the appearence of the deficit. On the other hand, Hecaen and Angelergues inferred from their material of 22 cases that lesions of the right hemisphere were present in 16 cases, lesions of the left hemisphere in 2 cases and bilateral lesions in 4 cases. They therefore concluded that the occurrence of facial agnosia is contingent upon the presence of a lesion of the right hemisphere. For the most part, the occipital lobes (but not necessarily the striate area) appear to be the site of primary involvement. The basic nature of the disorder has been a topic of some speculation. It has been thought to be the product of an interaction between a more generalized visual agnosia and a disturbance of the body schema (Hoff and Potzl, 1937; Potzl, 1953). In this regard, it may be noted that one or another type of visuoperceptive impairment (e.g., faulty identification of objects, colors, pictures or symbols and spatial disorientation) is often seen in association with facial agnosia. Other explanations have emphasized either sensory or higher-level perceptual deficits without invoking a disorder of the body schema. Thus Bay (1953), in harmony with his general position regarding the nature of agnosic disturbances, contended that facial agnosia is the expression of a primary sensory impairment that prevents simultaneous recognition of the several parts of a face so that it cannot be recognized as a distinctive global unity. The fact that patients with facial agnosia do in fact very often show primary sensory impairment, particularly visual field defects, supports Bay's conception. However, the equally evident fact that most patients with similar impairment of equal and even greater severity do not show this peculiar deficit can only weaken the cogency of his hypothesis. Moreover, there is also the consideration that the recognition of a face often follows a momentary glimpse of a single part of it and simultaneous recognition of a number of parts
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does not seem to be a necessary precondition for recognition. Faust (1947, 1955) has advanced the concept that facial agnosia represents a disorder in which the patient fails to grasp the detailed features of a complete stimulus situation so that its individuality is not identified. It follows from this that a patient suffering from impairment in the recognition of faces also should have difficulty in discriminating other types of stimuli as well and indeed Faust has described a single patient who could not distinguish between an ordinary chair and an armchair and whose recognition of visual stimuli under conditions of tachistoscopic presentation was defective. It is difficult to validate conceptions such as those of Bay and of Faust because the opportunity to study this uncommon complaint so rarely presents itself. On the other hand, if facial agnosia is a true neurological disability and not the product of psychodynamic factors (as some clinicians suspect), it is reasonable to expect that the basic impairment underlying it should be shown in less flagrant form by a larger number of patients with cerebral disease and that it should be possible to bring this impairment to light by appropriate methods of study. This consideration provided the impetus for the present investigation as weIl as for the recent studies of De Renzi and Spinnler (1966), De Renzi, Faglioni and Spinnler (1968) and Warrington and James (1967), in which the ability to recognize or remember faces was quantitatively assessed under controIled conditions of presentation. De Renzi and Spinnler (1966) investigated the performances of patients with hemispherically localized cerebral lesions on tasks involving immediate memory for photographs of faces, chairs and abstract line drawings. They found that the patients with right hemisphere disease performed on an inferior level to those with left hemisphere disease on the face and abstract drawing tests but not on the chair test. Moreover, while performances on the face and abstract drawing tests were positively intercorrelated in both groups of patients, the chair test was not correlated with either of the other two tasks. Visual field defects were associated with poor performance in the right hemisphere group but not in the left hemisphere group. Presence of aphasic disorder was not related to performance level. De Renzi and SpinnIer contend that their results provided no support for Faust's conception that facial agnosia is ascribable to a specific incapacity for identifying the "individuality" of a stimulus-complex. Instead they concluded that the deficit probably represents an impairment in visual discrimination and integration.
Facial recognition in brain-damaged patients
347
A subsequent study by De Renzi, Faglioni and Spinnler (1968) confirmed these findings of a hemispheric difference in performance and of a relationship between visual field defect and inferior performance in patients with right hemisphere lesions but not in those with left hemisphere lesions. Warrington and James (1967) similarly investigated immediate memory for faces but, in addition, also assessed the recognition of the faces of well-known public figures (e.g., Winston Churchill, President Kennedy) in patients with right and left hemisphere disease. They found that the patients with lesions of the right hemisphere performed on an inferior level on both tests. However, there was no correlation between scores on the two tests in either group, indicating the absence of a common factor in the two types of performance. In view of this lack of correlation and the fact that facial agnosia appears to be primarily an impairment in recognizing familiar faces, Warrington and James express doubt that tests of the ability to recognize unfamiliar faces are relevant to the problem of facial agnosia. We have investigated this question of impairment of facial recognition in patients with cerebral disease in a somewhat different manner. A matching procedure, which makes no demands upon immediate memory, has been employed. The tasks presented to the subject have involved not only matching identical photographs of an unfamiliar face but also matching different photographs of the same face. MATERIALS AND METHODS
Materials and procedure
Photographs (2 in. X 2 in.) of front, three-quarter and profile views of draped subjects were taken under varied lighting conditions. As a result of pilot testing, a selection of these photograph was made and a test of facial recognition calling for 54 responses was developed. The test consists of 3 parts: A - Matching of identical front-view photographs (Figure 1A); the subject is presented with a single front-view photograph of a face and instructed to identify it (by pointing to it or calling its number) in a display of 6 front-view photographs placed at the right of the single photograph; 3 male and 3 female faces are presented for matching, calling for a total of 6 responses.
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A. L. Benton and M. W . Van Allen
B - Matching of front-view with three-quarter-view photographs (Figure 1B); the subject is presented with a single front-view photograph of a face and instructed to locate it 3 times in a display of 6 three-quarter-views, 3 being of the presented face and 3 being of other faces; 4 male and 4 female faces are presented for matching, calling for a total of 24 responses. C - Matching of front-view photographs under different lighting conditions (Figure 1C); the subject is presented with a single frontview photograph of a face taken under full lighting conditions and instructed to locate it 3 times in a display of 6 front views taken under different lighting conditions; 3 photographs are of the presented face and 3 are of other faces; 4 male and 4 female faces are presented for matching, calling for a total of 24 responses. Thus the test calls for 54 scorable responses. Since the probability of chance success is 1 in 6 in Part A and 1 in 2 in Part Band C, a score of 25 may be expected on the basis of chance alone. Hence the effective range of scores may be considered to be 25-54. Subjects
The test was given to 111 patients without obvious evidence or history of cerebral disease who were seen on the neurological, neurosurgical and medical services of the University Hospitals, Iowa City. Range of ages in this control group was 16-65 years and educational level ranged from 6 to 16 years. Twenty-two patients with lesions apparently confined to the left hemisphere and 15 patients with lesions apparently confined to the right hemisphere were given the test. Range of ages in the left hemisphere group was 19-63 years and educational level ranged from 5 to 16 years. In the right hemisphere group, range of ages was 16-60 years and' educational level ranged from 7 to 16 years. The status of the patients in the two groups with respect to type of lesion is outlined in Table 1. It will be noted that cerebrovascular disease was the most frequent diagnosis in the left hemisphere group; in contrast, intrinsic neoplasm was the most frequent diagnosis in the right hemisphere group.
A
•
II
•
•
II.
•
•
•
B
•
•
•
II.
•
•
•
c
f
~
•
•
i
•
•
Fig. 1 - A: test item calling for matching of identical front views; B: test item calling for matching of frontal view with threeLjuarter views; C: test item calling for matching of frontal views under different lighting conditions.
II.
•
•
Facial recognition in brain-damaged patients
349
TABLE I
Classification of Cases with Respect to Type of Lesion
Left hemisphere cases
Vascular Neoplasm Trauma Atrophy
Right hemisphere cases
= 15)
(N =22)
(N
16 (73%) 4 (18%)
5 (33%) 8*(52%) 1 (7%) 1 (7%)
2 (9%)
* Intrinsic neoplasm (7); Meningeoma (1).
RESULTS
Normative observations
The total sample of 111 control patients was divided into subsamples according to age, sex and educational level in order to assess the influence of these factors on performance level (Table II). InspecTABLE II
Mean Scores of Control Subgroups Age range: 16-50 years Males with 12 + years of education (N = 24) Males with < 12 years of education (N 9) 33) Females with 12 + years of education (N Females with < 12 years of education (N = 26)
= =
Mean 46.5 46.7 46.2 44.8
Range 36-53 43-51 35-54 37-50
42.9 41.6
39-52 38-51
Older age groups 51-60 years (all subjects N = 12) 61-70 years (all subjects N = 7)
tion of data for patients under the age of 51 indicates no important differences attributable to sex or educational level. As will be seen, the normative date for older subjects are quite meagre. They suggest a moderate decline in performance level with increasing age. However, it will be noted that the range of scores in the older age groups is not wider than in the younger groups and that the lowest scores were
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350
in fact made by some younger subjects. With these considerations in mind, it was felt that, for the purposes of the present study, it was justifiable to combine the subsamples into a single total sample of control patients. In Table III are shown the mean scores of this TABLE III
Mean Scores
Left hemisphere
Control (SD
Right hemisphere
42.5 (SD = 5.0)
45.3
= 4.5)
(SD
34.7
= 6.4)
Differences Control vs. Left Control vs. Right Right vs. Left
2.8 (t = 2.67; p 10.6 (t = 8.04; p 7.8 (t = 4.00; p
< .01) < .001) < .001)
sample and in Table IV are shown the distributions of the individual scores. TABLE IV
Distributions of Scores Right
Score
Control
Left
52-54 49-51 46-48 43-45 40-42 37-39
7 25 25 25 17 9
2 4 6 4 3
3
34-36
3
2
4
1
31-33 28-30 25-27
1
1
3
2
111
22
15
Performances of patients with cerebral disease
The mean scores of the two groups of patients with cerebral disease are shown in Table III. It will be seen that the overall performance levels of both groups are significantly lower than that of the control patients. However, it will also be noted that the mean score
Facial recognition in brain-damaged patients
351
of the patients with right hemisphere disease is significantly lower than that of the -patients with left hemisphere disease. Table IV shows the distributions of the individual scores of the brain-damaged groups in comparison to that of the control patients. The fact that a significant proportion of patients with right hemisphere lesions made grossly inferior performance is quite clear. As will be seen, the scores of 6 (40 per cent) of these 15 patients were below that of the poorest control patients, while this was true of only 1 (4.5 per cent) of the patients with left hemisphere disease. If a score of 36 or less (i.e., a score exceeded by more than 97 per cent of the controls) is adopted as a criterion of defective performance, a majority (66.7 per cent) of the patients with right hemisphere disease would be classified as impaired, as compared to 3 (13.6 per cent) of the patients with left hemisphere disease. Performance level and visual field defect
Visual field defects were demonstrated in 8 of the 15 patients with right hemisphere disease and in 7 of the 22 patients with left hemisphere disease. The mean performance levels of the patients with and without visual field defects in the two groups are shown in Table V. TABLE V
Visual Field Defects and Performance Level
Right hemisphere cases Field defect (N
= 8)
Mean score = 35.5 Range of scores: 28-50
Field defect (N
= 7)
Mean score = 41.4 Range of scores: 35-51
No field defect (N
= 7)
Mean score = 33.9 Range of scores: 26-44 Left hemisphere cases No field defect (N
= 15)
Mean score = 42.9 Range of scores: 31-50
It is evident from inspection of this table that performance level was not related to the presence of visual field defect in either group of patients.
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Performance level mid aphasia
Ten of the 22 patients with left hemisphere disease were clinically aphasic in the sense that they showed manifest disturbances in expressive language. In some cases, language understanding was also clearly impaired; in the other cases, impairment in language comprehension, if present, was minimal. The mean performance levels of the aphasic and non-aphasic patients are presented in Table VI. No relationship between performance on the test of facial recognition and the presence of clinically manifest aphasic disorder is shown. TABLE VI
Aphasia and Performance Level
Left hemisphere cases Aphasic (N
= 10)
Not aphasic (N
Mean score
=
Mean score = 42.6
42.3
Range of scores: 35·48
With VFD (N Mean score
= 2)
= 41.0
Without VFD (N Mean score
= 8)
= 42.6
= 12)
Range of scores: 31-51
With VFD (N Mean score
= 5)
= 42.6
Without VFD (N Mean score
= 7)
= 42.6
Performance level and intrahemispheric locus of lesion
It was possible to specify the primary site of pathologic involvement in 13 of the 15 cases of right hemisphere disease and in 13 of the 22 cases of left hemisphere disease. The performance levels of subgroups of patients classified according to intrahemispheric locus of lesion are shown in Table VII. No systematic trends are apparent. It will be noted particularly that in both hemispheric groups the performance levels of the patients with lesions apparently confined to the frontal lobes are not higher than those of the patients with lesions of the parieto-occipital area.
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TABLE VII
Locus of Lesion and Performance Level
Mean scores Right hemisphere
Left hemisphere
Frontal
(4) 33_8
(3) 38.7
Temporal Temporo-parietal Temporo-occipital
(2) 42.5
(3) 46.0
Parietal Parieto-occipital Fronto-parietal
(7) 35.0
(7) 42.9
Undetermined
(2) 28.0
(9) 42.2
Performance level and type of lesion
Since the two hemispheric groups were not comparable in respect to the relative frequency of different types of lesions, an analysis of the relationship between performance level and type of lesion was made. The findings are shown in Table VIII. It will be noted that, in the right hemisphere group, the performance of the intrinsic neoplasm subgroup is not inferior to the vascular subgroup. Grossly
TABLE VIII
Type of Lesion and Performance Level
Right hemisphere cases (Mean scores) Neoplastic (N = 8)* Vascular (N = 5) Traumatic (N = 1) Atrophic (N = 1)
34.8
31.2
50 35
Left hemisphere cases (Mean scores) Neoplastic (N = 4) Vascular (N = 16) Atrophic (N = 2)
42.0
43 .1 38.0
* Intrinsic neoplasm (7), Mean score = 35.7; Meningeoma (1), Score = 28.
defective performances (i.e., scores of less than 34) were made by 2 (29 per cent) of the 7 patients with intrinsic neoplasm but also by 3 (60 per cent) of the 5 patients with vascular disease.
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DISCUSSION
Our results clearly indicate that impairment in facial recognition, as assessed by the task presented to our patients, is closely associated with disease of the right hemisphere. The patients with right hemisphere lesions performed on a significantly lower level than those with left hemisphere disease. Moreover, the most grossly defective performances were made practically only by patients with disease of the right hemisphere. The observed differences between the two unilateral groups cannot be ascribed to such factors as presence or absence of of visual field defect, type of lesion or intrahemispheric locus of lesion. In comparative clinical studies of the type exemplified by the present investigation, the factor of size of lesion usuany remains an uncontrolled variable . This circumstance poses a problem in interpretation if there is reason to suspect inequality with respect to size of lesion in the two hemispheric groups. There are considerations which raise the question of whether random selection of patients on a neurological or neurosurgical service may not tend to result in the formation of a sample of patients with right hemisphere lesions of unlimited extent as compared to a sample of patients with left hemisphere lesions of limited extent. For example, it seems possible that, because of the more handicapping effects of left hemisphere lesions in general (language disturbance, impairment of the preferred hand), patients with such lesions will be seen for study and treatment at an earlier, less advanced stage of disease than patients with lesions of the right hemisphere. Moreover, an extensive lesion of the left hemisphere may render a patient so severely aphasic that he cannot be made to understand test instructions and he is therefore excluded from a study. This is not likely to happen in the case of patients with extensive lesions of the right hemisphere who typically retain a fair degree of language understanding. However, a number of observations make it seem unlikely that the variable of size of lesion was a significant determinant of the interhemispheric difference in performance found in the present study. First, there is the finding that the aphasic patients with left hemisphere lesions did not perform more poorly than the non-aphasic patients with left hemisphere lesions. We have no direct evidence that these two subgroups differed in respect to extent of lesion. However, it may be presumed that by definition the non-aphasic patients had
Facial recognition in brain-damaged patients
355
lesions of limited extent in the sense that the language zone was not compromised and that this limitation does not apply to the aphasic patients. Yet no difference in performance level was observed. Secondly, there is the consideration that patients with lesions confined to one or the other frontal lobe did not differ in performance from their counterparts with post-Rolandic lesions. This was particularly noteworthy in the case of patients with right frontal lesions who showed as high a frequency of failure as those with right parieto-occipital lesions. Thirdly, patients with infiltrating neoplasms of the right hemisphere, some of which probably extended into neighboring areas, did not perform at a lower level than patients with other types of lesions in the right hemisphere. Finally, inspection of the individual cases discloses instances of defective performance on the part of some patients with right hemisphere lesions of apparently rather limited extent. The relationship of the findings to the symptom of "facial agnosia" remains problematical. No patient in the study spontaneously complained of inability to recognize familiar faces. The finding in this study and those of De Renzi and Spinnler (1966) and of Warrington and James (1967) of right hemisphere "dominance" for performance on facial recognition tasks is in consonance with the generalization that facial agnosia is preeminently a complaint of patients with disease of the right hemisphere. On the other hand, as Warrington and James have pointed out, facial agnosia involves loss of recognition of familiar faces, an operation which presumably involves memory processes, and indeed they speculate as to whether the symptom may not represent a partial form of the amnesic syndrome. In any case, since defective discrimination of unfamiliar faces appears to be specifically associated with right hemisphere disease, it is of interest in its own right, independently of its possible relationship to the clinical complaint of facial agnosia. The question then arises as to the nature of the basic impairment underlying this performance deficit. Do patients who fail this task suffer from significant visual impairment so that they do not receive the basic sensory information required to effect the discrimination? Parenthetically, it may be noted that this question in more general form has been raised about other forms of "agnosia" as well, e.g., visual object agnosia, visuospatial agnosia, tactile agnosia (Bay, 1953; Bender and Feldman, 1965). All the patients in our study appeared to have adequate visual acuity, as judged from notations in the case records. However, a standard
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A. L. Ben/on and M. W . Van Allen
assessment of visual acuity was not done as part of the study and it would be of interest to explore the influence of this as well as other visuosensory factors on performance level. De Renzi and Spinnler found an association between inferior performance and visual field defect in their patients with right hemisphere disease but not in those with left hemisphere lesions. As has been noted, our own findings were quite negative in this respect . In summary, it does not appear that one deals here with a performance deficit which is explainable in terms of simple sensory impairment. General mental impairment also needs to be considered as a possible determinant of defective performance. In a critique of the concept of agnosia, Bender and Feldman (1965) have advanced the hypothesis that the performance deficits which are placed in this category are the product of a combination in varying degrees of sensory impairment and general mental impairment. Applying this idea to defective facial discrimination, it may be asked whether the deficit is not simply a partial expression of general behavioral incompetence. Our observations do not support the idea. Of the different subgroups, one would expect that the aphasic patients would be most impaired intellectually. However, as has been shown, not only were these patients not inferior to non-aphasic patients with left hemisphere disease but they were decidedly superior to those with right hemisphere lesions. It will be recalled that De Renzi and Spinnler (1966) also found no evidence for an association between aphasia and defective facial recognition. It was not possible to evaluate the concept of Bender and Feldman that a combination of general intellectual impairment and basic sensory deficit is responsible for the appearance of agnosic phenomena since only two aphasic patients showed visual field defects. One of these made a poor performance but the other made a relatively good score on the test of facial discrimination. It may also be observed that the one patient in the left hemisphere group who made a grossly defective performance was not aphasic, showed no visual field defects and was noted as having 20/20 vision bilaterally. Thus it seems likely that "higher-level" visuoperceptive deficit, i.e. , impairment in the integration of received sensory data, underlies failure in facial discrimination. If this is so, it should be possible to disclose evidence of this basic impairment in other task performances. De Renzi and Spinnler (1966) found a significant positive correlation between performance level on tasks involving immediate memory for
Facial recognition in brain-damaged patients
357
faces and immediate memory for abstract line drawings in both patients with right hemisphere and with left hemisphere disease. They therefore concluded that a more generalized impairment in visual discrimination underlies defective facial recognition. In an investigation of the relationship between facial recognition and various other task performances in mental defectives, Benton and Gordon (1964) found that performance on a test involving the discrimination of patterns of brightness correlated most closely with performance on the facial recognition test. The possible implications of this finding deserve further exploration, particularly in patients with focal cerebral disease. Empirical observations to date are not sufficient to provide the basis for a precise definition of the disability underlying defective facial recognition. However, two facts seem to be reasonably clear. First, the disability is shown with greater frequency and in more severe form by patients with lesions of the right hemisphere; hence, by inference, it would appear that the right hemisphere plays a special role in the mediation of this ability. Secondly, the weight of evidence suggests that the disability involves faulty integration and discrimination of sensory data rather than simple sensory deficit. Thus defective facial recognition takes its place among those types of performances which have been found to be particularly severely impaired as a consequence of disease of the right hemisphere. The nature of the basic functions or abilities underlying these performances remains an unanswered question. SUMMARY
A test requiring the identification of unfamiliar faces was developed and given to groups of patients with lesions of the left or the right hemisphere as well as to a large group of control patients. Performance level in the control group showed a slight decline with age but was not related to education or sex. The mean performance levels of both brain-damaged groups were significantly inferior to that of the control group. In addition, however, the mean performance level of the patients with right hemisphere lesions was significantly inferior to that of the patients with left hemisphere lesions and grossly defective performances were made mainly by patients with right hemisphere lesions. Performance level was not related to the presence of visual field defect, the presence of aphasia, type of lesion or intrahemispheric locus of lesion. A number of considerations suggested that the observed interhemispheric difference in performance
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was not related to a possible difference in the extent of lesion in the two groups. The observations clearly indicate that impairment in facial recognition, as assessed by the procedures utilized in the study, is rather closely associated with disease of the right hemisphere. The relationship of the findings to the clinical complaint of prosopagnosia and the nature of the basic disabilities underlying defective facial recognition are considered. Acknowledgment. We are indebted to Dr. Musetta Gordon for her aid in developing the test materials and in conducting the pilot study which preceded the present investigation. REFERENCES BAY, E. (1953) Disturbances of visual perception and their examination, "Brain," 76,
515-550. BENDER, M. B., and FELDMAN, M. (1965) The so-called visual agnosias, Proc. 8th Internat. Congo NeuroL, 3, 153-156. BENTON, A. L., and GORDON, M. C. (1964) Aspects of facial recognition:n mental deficiency, Paper presented at Meeting of American Association on Mental Deficiency, Omaha . DE RENZI, E., FAGLIONI, P ., and SPINNLER, R . (1968) The performance of patients with unilateral brain damage on face recognition tasks, "Cortex," 4, 17-34. - , and SPINNLER, H. (1966) Facial recognition in brain-damaged patients, "Neurology," 16, 145-152. FAUST, (1947) Partielle Seelenblindheit nach Occipitalhirnverletzung mit besonderer Beeintriichtigung des Physiognomieerkennens, "Nervenarzt," 18, 294-297. (1955) Die Zerebrale Herdstorungen bei Hinterhauptsverletzungen und ihre Beurteilung, Georg Thieme Verlag, Stuttgart. HtCAEN, H., and ANGELERGUES , R. (1962) Agnosia for faces (prosopagnosia), "Arch. NeuroL," 7, 92-100. HOFF, R., and POTZL, O. (1937) Ober eine optisch-agnostische Storung des "Physiognomie-Gedachtnisses" (Beziehung zur Riickbildung eines Wortblindheit) , "Ztschr. NeuroL Psychiat.," 159, 367-395. POTZL, O. (1953) Zur Agnosie des Physiognomiegedachtnisses, "Wiener Ztschr. Nervenheilk.," 6, 335-354. WARRINGTON, E. K., and JAMES, M. (1967) An experimental investigation of facial recognition in patients with unilateral cerebral lesions, "Cortex," 3, 317-326.
c.
Prof. A. L. Benton, Department of Neurology, University Hospital, Iowa City, Iowa 52240 (U.S.A.).