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Prosopagnosia and facial discrimination
167
Journul of the neurological Sciences Elsevier Publishing Company, Amsterdam
Printed
in The Netherlands
and Facial Discrimination
Prosopagnosia A. L. BENTON
AND
(Received
M. W. VAN
3 June,
ALLEN
1971)
INTRODUCTION
The clinical symptom of “prosopagnosia”, i.e., failure to recognize the faces of,fhmiliul persons, has provided the starting point for a number of experiment’al studies . ‘of _ the
capacity of patients with cerebral disease to discriminate representations of u$miliai faces under various conditions of stimulus presentation (cf De Renzi and Spinnler 1966 : Warrington and James 1967 ; De Renzi, Faglioni and Spinnler 1968 ; Benton and Van Allen 1968; Tzavaras, Hecaen and Le Bras 1970; Yin 1970). Undoubtedly the original impetus for this development was the assumption that the experimental procedure probed the same cognitive and perceptual abilities as those involved in the recognition of the faces of familiar persons. However, despite the finding that both the clinical complaint and impairment in the discrimination of unfamiliar faces as assessed by special tests have been found to be associated with disease of the right hemisphere, it has become increasingly apparent that the two deficits are not necessarily identical and that their interrelations still need to be worked out. Evidence for the problematic nature of the association between prosopagnosia and disturbances in the discrimination of unfamiliar faces as assessed experimentally comes from two sources. First, Warrington and James (1967) found that, although impairment in both the discrimination of unfamiliar faces and in the recognition of well-known public figures was associated with right hemisphere disease, there was no correlation between scores on the two tests in either right-hemisphere-damaged or left-hemisphere-damaged patients. This lack of empirical evidence for a common factor underlying the two performances, coupled with the fact that failure to recognize the faces of well-known public figures is a common feature of the prosopagnosic syndrome, led the authors to express doubt that facial agnosia and impairment in the discrimination of unfamiliar faces are ascribable to the same cognitive defects. The second line of evidence bearing on the relationship between the two disabilities comes from the few instances in which patients with prosopagnosia have been * This Investigation was supported by Research Grant NS-00616 and Program-Project Grant NS-03354 from the National Institute of Neurological Diseases and Stroke. Neurosensory Center Publication No. 224.
J. neural. Sci.. 1972, 15: 167 172
168 given tests assessing
A.
L. 13ENTON. M. W. VAN
their capacity
to discriminate
ALLEN
unfamiliar
faces and their perfor-
mances compared with those of both control subjects and patients with cerebral disease who were not prosopagnosic. Three such cases have been reported recently in the literature. De Rcnzi c’t trl. (196X) have described a 54-year-old man with a history of a probable cerebrovascular accident 2 years previously whose “main complaint was that he was unable to recognize people, even his wife and relatives, unless he heard their voices”. He also failed to identify well-known public figures from inspection of their faces. He was alert and cooperative, free from general mental impairment, but did have a left homonymous superior quadrantanopia. Given standardized tests involving the discrimination of unfamiliar faces, his performance was markedly defective and indeed significantly below the relatively poor level which is characteristic of patients with disease of the right hemisphere. The second case has been reported by Assal (1969). Following removal of a large (100 ml) intracerebral hematoma in the right parieto-occipital area, this 57-year-old man was oriented for time and place and showed no memory deficits or impairment in verbal intelligence. However, he did suffer from various forms of spatial disability including disturbances in route-finding, apraxia for dressing and visuoconstructive deficits as well as a left homonymous hemianopia and left somatosensory defect. He recognized his relatives only after they had spoken to him. Physicians and nurses were recognized when they were in uniform but not when they were in civilian dress. A physician, having been identified by the patient, changed his white coat for an overcoat: the patient failed to recognize him until spoken to. Photographs of celebrities that were identified with ease by control subjects posed great difficulty for him. During this period when he showed pronounced “facial agnosia”, the patient was given a battery of tests in which he had to match unfamiliar faces with each other under various conditions of stimulus presentation (c$ Tzavaras rt al. 1970). His performance on these tests was well within normal limits. The findings in a third prosopagnosic patient, originally described by Rondot, Tzavaras and Garcin (1967), have been reported recently by Tzavaras et ul. (1970). An interesting feature of this case is that the facial agnosia of this 61-year-old man has persisted for 16 years following a cerebrovascular accident, the other sequelae being a left homonymous quadrantanopia, spatial disorientation and impaired color recognition. Over the course of years the difficulties in spatial orientation and color recognition have very largely disappeared. The visual field defect has changed in character, taking the form of a superior altitudinal hemianopia, this finding taken together with other signs suggesting the presence of an irreversible bilateral lesion. As indicated, the difficulty in recognizing the faces of familiar persons has not changed and the patient has developed various stratagems to achieve identification on the basis of other cues such as gait, coiffure and spectacles. When his wife put on a nurse’s uniform, he could not identify her alongside other nurses. Nevertheless, on a battery of tests assessing the capacity to discriminate among unfamiliar faces, his performances were almost exactly equivalent to the mean scores obtained from control subjects. In summary. the first of these 3 case reports found a prosopagnosic patient to be markedly impaired in the discrimination of unfamiliar faces, a result which would J. neural. Sri., 1972. I5 : 167~ 172
PKOSOPAGNOSIA
support
the conclusion
169
AND FACIAL DISCRIMIiKATION
that the same basic disability
underlies
both facial agnosia
and defective visual discrimination. On the other hand, the second and third case reports describe prosopagnosic patients whose performances on fairly demanding tests of facial discrimination were essentially normal and this outcome, argues for a dissociation between the two types of impairment. We have had the opportunity
of studying
yet another
prosopagnosic
of course, patient
in
considerable detail and, in view of the paucity of published data on the question of the performances of such patients on tasks requiring the discrimination of unfamiliar faces, it appears worth-while to describe the findings in this case and to consider their implications. It may be mentioned at once that this patient performed on a mediocre level. but within unfamiliar faces.
broad
normal
limits, on a test requiring
the discrimination
of
CASE REPORT A 24.year-old right-handed white woman was admitted to the Department of Neurology. University l{ospitals. lowa City. 3 weeks after an apparently normal labor and delivery, complicated only by a bladder infcctlon. The day before admission she complained of headache, mild confusion and had a grand mal TelTurc. Some hours later she had a second grand mal seizure which began with convulsive movements of the left arm and leg. On admission she was lethargic but did respond to commands: she showed no localizing neurological signs but did have bilateral Babinski signs. Rectal temperature was 100.6” F. Her condition changed littlc over the 1~x1 several days with fever to 101.5 F. persistent lethargy. confusion and IrritabiliI\. There was mild rc\i\tancc to flcwion of the neck. lilt-inalgsis, hcmogram and blood serology wcrc normal. The spinal fluid pressure was 220 mm of H,O. the fluid was clear. There were no cells and pr~~tcin wah 40 mg;lOO ml. Blood chemistry studies were normal. Roentgenograms of chest and skull disclosed only maxillary sinusitis. An electroencephalogram (EEG) done 2 days after admission was very abnormal with diffuse slow activity. A tentative diagnosis ofencephalitls was made although a subsequent series of complement lixatlon tests were negative. Five days alter admIssIon she became more responsive, answered simple questions but had no memor! for her illness. Attempts at visual field plotting at this time were unsuccessful. She remained disoriented and could not remember the names of her children. An EEG taken 9 days after admission was much less abnormal with poorlv developed alpha activity and small spikes. Ten days after admission she experienced difficulty in wriiing a letter and complained that her script “did not look like writing”. She improved steadily over the course of the 10th to the 15th day. She manifested no focal signs and the visual fields were full to confrontation. She was afebrile. her confusional state disappeared and she interacted normally with other people. However, she still showed gaps in personal memory and it was evident that she had difficulty in identifying familiar persons. She was seen for neuropsychological assessment on the 16th and 17th days after admission. Her improvement continued and she was discharged 33 days after admission. A radioactive brain scan. done 19 days after admission, was found to be normal. Pneumoencephalography 28 days after admission also yielded normal findings. A third EEG, taken 30 days after admission. was only slightly abnormal with posterior slow activity. Discharge diagnosis was viral encephalitis. She was quite well when she returned for check-up 3 months after discharge.
By the 15th day after admission, her confusional state had disappeared. She still showed a memor) deficit but this was improving steadily. At this point in time, it became apparent that she had marked difficulty in identifying familiar persons. When her husband visited her, she at first failed to recognize him and only after some minutes of conversation did she identify him. When she was shown pictures of her children. she failed to recognize them and said, “they don’t look like they should”. Failure to recognize well-known persons. a common feature of the prosopagnosic syndrome. was also the subject of spontaneous complaint. When watching television. she was unable to identify star performers who were well-known to her until they spoke or sang. She also commented that people looked younger to her than she surmised they really w/cre. This last complaint was investigated by having her estimate the ages of 4 members of the medical staff. Her guesses were reasonably accurate with a slight tendency toward underestimation of age. Two middle-aged men. 55 years and 46 years old. were judged to be 50 years and 45 years old. respectl\cl>.
170
A. L. BENTON,
M. W. VAN ALLEN
She judged a 30-year-old man to be 28 years old and a 28-year-old woman to be 25 years old. She was given a 54-item test calling for the matching of unfamiliar faces under different conditions of \t~mulus presentation (cf: Benton and Van Allen 1968). The first part of the test (6 responses) requires the matching of identical front-view photographs of faces: the subject is presented with a single front-vrew photograph and instructed to identify it (by pointing or calling its number) on a display of 6 front-view photographs placed to the right of the single photograph. In the second part of the test (24 responses), the subject is required to match a front-view photograph with three-quarters view photographs of the same person on the multiple choice display. In the third part of the test (24 responses). he matches frontview photographs of the same person which have been taken under different lighting conditions. The patient correctly matched all 6 items of the first part of the test, She made I9 correct identifications on the 24 trials of the second part and 17 correct identifications on the 24 trials of the third part. Hence her total score was 42 correct responses which may be compared with the mean score of 45.6 obtained from a group of 107 normal subjects within the age range of 16-55 years. Inspection of the distribution of scores of this normative group shows that her score was at the 2lst percentile of the distribution. i.e.. it was exceedalthough mediocre, was well within the limits of normal ed by 79 1,, of the group. Thus her performance, variation. It was also decidedly higher than the mean score (34.7) made by a group of non-proropagnosic patients with right hemisphere disease (c$ Benton and Van Allen 1968).
She was given a battery of mental tests on the 16th and 17th days after admission. Although she still showed gaps in personal memory for events extending over the previous 4 or 5 years, her temporal orientation was adequate. She knew the year, month and day of week but misstated the day of the month by 1 day and the time of day by 35 min. Objectively scored, her performance was within normal limits (c$ Benton, Van Allen and Fogel 1964). She was completely free from aphasic disorder, performing normally on tests of reading and writing, as well as speaking and understanding. However, on detailed testing. she showed a variety of defects, most of these being in the area of visual perception, imagination and memory. Her ability to achieve recognition offragmented figures and to identify hidden figures was impaired. She copied designs well but was unable to reproduce them from memory under a no-delay condition. This defect in immediate visual memory was not shown in the auditory sphere; she was able to repeat 7 digits and to reverse 4 digits. Tactile kinesthetic form perception (tracing sandpaper figures of an abstract nature) was intact in both hands. She showed no difficulty in discriminating between right and left on her own body but did fail to make the necessary 180” reversal in pointing to lateral body parts on the confronting examiner. Arithmettc calculation and reasoning were adequate. Her fund of general information was extremely poor. even for a person with her rather limited schooling.
DISCUSSION
The findings in this case fully support the concept that the disabilities underlying prosopagnosia and impairment in performance on the visuoperceptual task of discriminating unfamiliar faces are, or at least may be, dissociable. It follows that higherlevel perceptual disability cannot serve as a y~nrral explanation of the clinical symptom although it may apply validly to some cases. Some (but by no means all) prosopagnosic patients complain that faces appear to them to be “distorted”, “contorted”. “warped”, or “flat” and this has been called a “metamorphopsic form” of facial agnosia by Hecaen and Angelergues (1962). However, it is doubtful whether aberrations of this type are a major determinant of the failure to recognize familiar faces for. as Htcaen and Angelergues themselves point out, facial recognition in these patients is often less impaired than in those who do not experience these visuoperceptive distortions. Moreover, as attested to by more than a score of case reports, metamorphopsia as a primary complaint is rarely accompanied by facial agnosia. The case of De Renzi rt al. (1968) did show a concomitance of facial agnosia and quite severe disability in the discrimination of unfamiliar faces and it seemed reasonable to explain the clinical symptom in terms of the visuoperceptive disability. HowJ. nr?C-of. ser.. 197’.
IS: 167 177
PROSOPAGNOSIA
171
AND FACIAL DISCRIMINATION
ever, aside from the fact that three subsequent
case reports
have now shown
that
prosopagnosia may occur in the absence ofthe perceptual disability, there.is the further consideration that most patients with extremely severe impairment in the discrimination of unfamiliar faces show no signs of facial agnosia. If then facial agnosia is not easily ascribed to visuoperceptive defects, the question arises as to what the underlying disability (or disabilities) may be. A definitive answer cannot be given but it seems likely that the primary factor may be of an associative nature
involving
impairment
in the integration
of current
with past experience.
Their
findings led Warrington and James (1967) not only to draw a distinction between impaired discrimination of unfamiliar faces and prosopagnosia but also to speculate that the latter, as well as the associated
disability
in recognizing
celebrities,
represents
a partial form of the “amnesic syndrome”. The finding that the prosopagnosia of our patient showed itself within a context of a rather mild yet pervasive loss of memory for the recent past fits in with this hypothesis. In any event, if the disability is classitied as a form of agnosia (some justification for which can be derived from the fact that it is specifically associated with a single sensory modality). it is an agnosia of an “associative” rather than “apperceptive” type (Lissauer 1890). The fact that impairment in the perception and identification of unfamiliar faces has been found to be dissociated from facial agnosia has had interesting consequences since the purely perceptual disability has proved to be of neurological interest in its own right. It is closely associated with disease of the right hemisphere and at the same time it is clear that a basic sensory defect (e.g. poor visual acuity, visual field defect) or general mental impairment cannot be invoked as adequate explanations for its appearance. A likely hypothesis is that a “higher order” visuoperceptive defect (i.e., impairment in the processing and integration of visual information) is responsible for failure on facial discrimination tasks as well as on other tasks (e.g. mixed figures. complex form discrimination) making the same demands on perceptual integration. For example, De Renzi and Spinnler (1966) found that defective facial recognition was associated with failure in discriminating abstract line drawings and concluded that impairment in visual discrimination and integration was responsible for both types of performance deficits. Similarly, Benton and Gordon (1971) have shown that facial discrimination is particularly closely related to the ability to discriminate differential brightness patterns and they interpret this result as indicating that pattern discrimination involving the utilization of differences in brightness as cues is an important component of facial recognition. Another possibility is that there does indeed exist a distinctive primary ability to recognize faces which is subserved by neural mechanisms in the parieto-occipital area of the right hemisphere (or perhaps of both hemispheres). This rather extreme hypothesis, advanced by Bodamer (1947) and others, would seem at first glance to be most improbable. However, it has in fact received some empirical support in recent studies (Tzavaras et al. 1970; Yin 1970) which suggests that there is something “special” about facial recognition and that it may be useful and meaningful to make a distinction between this particular form of visual discrimination and other tasks requiring the processing and integration of visual information.
J. neural. Sri.. 1972, 15: 167-172
172
A. L. BENTON,
M. W. VAN ALLEN
SUMMARY
The relations between prosopagnosia and the ability to discriminate unfamiliar faces are reviewed and the performance of a prosopagnosic patient on a facial discrimination test as well as on other tasks requiring the processing and integration of visual information is described. The finding that this patient showed essentially normal ability
to discriminate
unfamiliar
faces supports
the contention
that prosopagnosia
cannot be solely explained in terms of a general visuoperceptive impairment. The present state of our understanding of the disabilities underlying both prosopagnosia and defective discrimination of unfamiliar fzces is discussed. REFERENCES Ass~I.. G. (1969) Regression des troubles de la reconnaissance des physionomies et de la memoire topogrnphique cher un malade opCrC d’un htmatome intracerebral paritto-temporal droit. Rw. wurol.. 121: 184185. BEXTON. A. L. AND M. W. VAN ALLEN (1968) Impairment in facial recognition in patients with cerebral disease. Cortex, 4: 344 358. BENTON, A. L. AND M. C. G~RU~N (1971) Correlates of facial recognition. ~rc~ns. Amcr ncwol. A,.\.. 96: In press. B~NTON. A. L., M. W. VAN ALLEN AND M. L. Fo~;~L (1964) Temporal orientation in cerebral disease. J. mv~. ment. Dir., 139: 1 lo- 119. BODAMER. J. (1947) Die Prosop-Agnosie, Arch. Pslxhirrr. Nercrnkr.. 179: 6654. DE RI:NZI, E. AND H. SPINNLER (1966) Facial recognition in brain-damaged patients. l’vw~o/o~/J~i .Mirrmwp~. 16: 1455152. DF RFNZI. E., P. FAGLI~NI AND H. SPINNLER (1968) The performance of patients with unilateral brain damage on face recognition tasks, Cwt~, 4: 17-34. H~CAEN, H. AND R. ANGELERCUES (1962) Agnosia for faces (prosopagnosia), Ard. Ncvm~l. /Chtc ), 7: 92~ 100. LISSAUFR, W. (1890) Ein Fall von Seelenblindheit nebst einen Beitrag zur Theorie Llerselben. .-lrc~h. P.wchiof. Nerwtzkr., 21 : 222. 270. RONDOT. P.. A. TZAVARAS AND R. GARUN (1967) Sur un cas de prosopagnosie persistant depuis quince ans, Rev. neural., 117: 424428. T~AV~RAS, A.. H. HBCAEN AND H. LE BRAS (1970) Le probltme de la specificite du deficit de la reconnaissance du visage humain lors des lesions htmispheriques unilattrales. Neurops!,cho/o!/i~/~ 8 : 403 416. WARRI~GTON, E. K. AND M. JAMES (1967) An experimental investigation of facial recognition in patients with unilateral cerebral lesions. Corze.u. 3 : 3 177326. YIX. R. K. (1970) Face recognition by brain-injured patients : a dissociable abihty? iVc/r~,,/~s~.(,ho/~,c/itr.X : 395402.
J. wurol. Si..
1972.
I5 : I67 I72
Journul of the neurological Sciences Elsevier Publishing Company, Amsterdam
Printed
in The Netherlands
and Facial Discrimination
Prosopagnosia A. L. BENTON
AND
(Received
M. W. VAN
3 June,
ALLEN
1971)
INTRODUCTION
The clinical symptom of “prosopagnosia”, i.e., failure to recognize the faces of,fhmiliul persons, has provided the starting point for a number of experiment’al studies . ‘of _ the
capacity of patients with cerebral disease to discriminate representations of u$miliai faces under various conditions of stimulus presentation (cf De Renzi and Spinnler 1966 : Warrington and James 1967 ; De Renzi, Faglioni and Spinnler 1968 ; Benton and Van Allen 1968; Tzavaras, Hecaen and Le Bras 1970; Yin 1970). Undoubtedly the original impetus for this development was the assumption that the experimental procedure probed the same cognitive and perceptual abilities as those involved in the recognition of the faces of familiar persons. However, despite the finding that both the clinical complaint and impairment in the discrimination of unfamiliar faces as assessed by special tests have been found to be associated with disease of the right hemisphere, it has become increasingly apparent that the two deficits are not necessarily identical and that their interrelations still need to be worked out. Evidence for the problematic nature of the association between prosopagnosia and disturbances in the discrimination of unfamiliar faces as assessed experimentally comes from two sources. First, Warrington and James (1967) found that, although impairment in both the discrimination of unfamiliar faces and in the recognition of well-known public figures was associated with right hemisphere disease, there was no correlation between scores on the two tests in either right-hemisphere-damaged or left-hemisphere-damaged patients. This lack of empirical evidence for a common factor underlying the two performances, coupled with the fact that failure to recognize the faces of well-known public figures is a common feature of the prosopagnosic syndrome, led the authors to express doubt that facial agnosia and impairment in the discrimination of unfamiliar faces are ascribable to the same cognitive defects. The second line of evidence bearing on the relationship between the two disabilities comes from the few instances in which patients with prosopagnosia have been * This Investigation was supported by Research Grant NS-00616 and Program-Project Grant NS-03354 from the National Institute of Neurological Diseases and Stroke. Neurosensory Center Publication No. 224.
J. neural. Sci.. 1972, 15: 167 172
168 given tests assessing
A.
L. 13ENTON. M. W. VAN
their capacity
to discriminate
ALLEN
unfamiliar
faces and their perfor-
mances compared with those of both control subjects and patients with cerebral disease who were not prosopagnosic. Three such cases have been reported recently in the literature. De Rcnzi c’t trl. (196X) have described a 54-year-old man with a history of a probable cerebrovascular accident 2 years previously whose “main complaint was that he was unable to recognize people, even his wife and relatives, unless he heard their voices”. He also failed to identify well-known public figures from inspection of their faces. He was alert and cooperative, free from general mental impairment, but did have a left homonymous superior quadrantanopia. Given standardized tests involving the discrimination of unfamiliar faces, his performance was markedly defective and indeed significantly below the relatively poor level which is characteristic of patients with disease of the right hemisphere. The second case has been reported by Assal (1969). Following removal of a large (100 ml) intracerebral hematoma in the right parieto-occipital area, this 57-year-old man was oriented for time and place and showed no memory deficits or impairment in verbal intelligence. However, he did suffer from various forms of spatial disability including disturbances in route-finding, apraxia for dressing and visuoconstructive deficits as well as a left homonymous hemianopia and left somatosensory defect. He recognized his relatives only after they had spoken to him. Physicians and nurses were recognized when they were in uniform but not when they were in civilian dress. A physician, having been identified by the patient, changed his white coat for an overcoat: the patient failed to recognize him until spoken to. Photographs of celebrities that were identified with ease by control subjects posed great difficulty for him. During this period when he showed pronounced “facial agnosia”, the patient was given a battery of tests in which he had to match unfamiliar faces with each other under various conditions of stimulus presentation (c$ Tzavaras rt al. 1970). His performance on these tests was well within normal limits. The findings in a third prosopagnosic patient, originally described by Rondot, Tzavaras and Garcin (1967), have been reported recently by Tzavaras et ul. (1970). An interesting feature of this case is that the facial agnosia of this 61-year-old man has persisted for 16 years following a cerebrovascular accident, the other sequelae being a left homonymous quadrantanopia, spatial disorientation and impaired color recognition. Over the course of years the difficulties in spatial orientation and color recognition have very largely disappeared. The visual field defect has changed in character, taking the form of a superior altitudinal hemianopia, this finding taken together with other signs suggesting the presence of an irreversible bilateral lesion. As indicated, the difficulty in recognizing the faces of familiar persons has not changed and the patient has developed various stratagems to achieve identification on the basis of other cues such as gait, coiffure and spectacles. When his wife put on a nurse’s uniform, he could not identify her alongside other nurses. Nevertheless, on a battery of tests assessing the capacity to discriminate among unfamiliar faces, his performances were almost exactly equivalent to the mean scores obtained from control subjects. In summary. the first of these 3 case reports found a prosopagnosic patient to be markedly impaired in the discrimination of unfamiliar faces, a result which would J. neural. Sri., 1972. I5 : 167~ 172
PKOSOPAGNOSIA
support
the conclusion
169
AND FACIAL DISCRIMIiKATION
that the same basic disability
underlies
both facial agnosia
and defective visual discrimination. On the other hand, the second and third case reports describe prosopagnosic patients whose performances on fairly demanding tests of facial discrimination were essentially normal and this outcome, argues for a dissociation between the two types of impairment. We have had the opportunity
of studying
yet another
prosopagnosic
of course, patient
in
considerable detail and, in view of the paucity of published data on the question of the performances of such patients on tasks requiring the discrimination of unfamiliar faces, it appears worth-while to describe the findings in this case and to consider their implications. It may be mentioned at once that this patient performed on a mediocre level. but within unfamiliar faces.
broad
normal
limits, on a test requiring
the discrimination
of
CASE REPORT A 24.year-old right-handed white woman was admitted to the Department of Neurology. University l{ospitals. lowa City. 3 weeks after an apparently normal labor and delivery, complicated only by a bladder infcctlon. The day before admission she complained of headache, mild confusion and had a grand mal TelTurc. Some hours later she had a second grand mal seizure which began with convulsive movements of the left arm and leg. On admission she was lethargic but did respond to commands: she showed no localizing neurological signs but did have bilateral Babinski signs. Rectal temperature was 100.6” F. Her condition changed littlc over the 1~x1 several days with fever to 101.5 F. persistent lethargy. confusion and IrritabiliI\. There was mild rc\i\tancc to flcwion of the neck. lilt-inalgsis, hcmogram and blood serology wcrc normal. The spinal fluid pressure was 220 mm of H,O. the fluid was clear. There were no cells and pr~~tcin wah 40 mg;lOO ml. Blood chemistry studies were normal. Roentgenograms of chest and skull disclosed only maxillary sinusitis. An electroencephalogram (EEG) done 2 days after admission was very abnormal with diffuse slow activity. A tentative diagnosis ofencephalitls was made although a subsequent series of complement lixatlon tests were negative. Five days alter admIssIon she became more responsive, answered simple questions but had no memor! for her illness. Attempts at visual field plotting at this time were unsuccessful. She remained disoriented and could not remember the names of her children. An EEG taken 9 days after admission was much less abnormal with poorlv developed alpha activity and small spikes. Ten days after admission she experienced difficulty in wriiing a letter and complained that her script “did not look like writing”. She improved steadily over the course of the 10th to the 15th day. She manifested no focal signs and the visual fields were full to confrontation. She was afebrile. her confusional state disappeared and she interacted normally with other people. However, she still showed gaps in personal memory and it was evident that she had difficulty in identifying familiar persons. She was seen for neuropsychological assessment on the 16th and 17th days after admission. Her improvement continued and she was discharged 33 days after admission. A radioactive brain scan. done 19 days after admission, was found to be normal. Pneumoencephalography 28 days after admission also yielded normal findings. A third EEG, taken 30 days after admission. was only slightly abnormal with posterior slow activity. Discharge diagnosis was viral encephalitis. She was quite well when she returned for check-up 3 months after discharge.
By the 15th day after admission, her confusional state had disappeared. She still showed a memor) deficit but this was improving steadily. At this point in time, it became apparent that she had marked difficulty in identifying familiar persons. When her husband visited her, she at first failed to recognize him and only after some minutes of conversation did she identify him. When she was shown pictures of her children. she failed to recognize them and said, “they don’t look like they should”. Failure to recognize well-known persons. a common feature of the prosopagnosic syndrome. was also the subject of spontaneous complaint. When watching television. she was unable to identify star performers who were well-known to her until they spoke or sang. She also commented that people looked younger to her than she surmised they really w/cre. This last complaint was investigated by having her estimate the ages of 4 members of the medical staff. Her guesses were reasonably accurate with a slight tendency toward underestimation of age. Two middle-aged men. 55 years and 46 years old. were judged to be 50 years and 45 years old. respectl\cl>.
170
A. L. BENTON,
M. W. VAN ALLEN
She judged a 30-year-old man to be 28 years old and a 28-year-old woman to be 25 years old. She was given a 54-item test calling for the matching of unfamiliar faces under different conditions of \t~mulus presentation (cf: Benton and Van Allen 1968). The first part of the test (6 responses) requires the matching of identical front-view photographs of faces: the subject is presented with a single front-vrew photograph and instructed to identify it (by pointing or calling its number) on a display of 6 front-view photographs placed to the right of the single photograph. In the second part of the test (24 responses), the subject is required to match a front-view photograph with three-quarters view photographs of the same person on the multiple choice display. In the third part of the test (24 responses). he matches frontview photographs of the same person which have been taken under different lighting conditions. The patient correctly matched all 6 items of the first part of the test, She made I9 correct identifications on the 24 trials of the second part and 17 correct identifications on the 24 trials of the third part. Hence her total score was 42 correct responses which may be compared with the mean score of 45.6 obtained from a group of 107 normal subjects within the age range of 16-55 years. Inspection of the distribution of scores of this normative group shows that her score was at the 2lst percentile of the distribution. i.e.. it was exceedalthough mediocre, was well within the limits of normal ed by 79 1,, of the group. Thus her performance, variation. It was also decidedly higher than the mean score (34.7) made by a group of non-proropagnosic patients with right hemisphere disease (c$ Benton and Van Allen 1968).
She was given a battery of mental tests on the 16th and 17th days after admission. Although she still showed gaps in personal memory for events extending over the previous 4 or 5 years, her temporal orientation was adequate. She knew the year, month and day of week but misstated the day of the month by 1 day and the time of day by 35 min. Objectively scored, her performance was within normal limits (c$ Benton, Van Allen and Fogel 1964). She was completely free from aphasic disorder, performing normally on tests of reading and writing, as well as speaking and understanding. However, on detailed testing. she showed a variety of defects, most of these being in the area of visual perception, imagination and memory. Her ability to achieve recognition offragmented figures and to identify hidden figures was impaired. She copied designs well but was unable to reproduce them from memory under a no-delay condition. This defect in immediate visual memory was not shown in the auditory sphere; she was able to repeat 7 digits and to reverse 4 digits. Tactile kinesthetic form perception (tracing sandpaper figures of an abstract nature) was intact in both hands. She showed no difficulty in discriminating between right and left on her own body but did fail to make the necessary 180” reversal in pointing to lateral body parts on the confronting examiner. Arithmettc calculation and reasoning were adequate. Her fund of general information was extremely poor. even for a person with her rather limited schooling.
DISCUSSION
The findings in this case fully support the concept that the disabilities underlying prosopagnosia and impairment in performance on the visuoperceptual task of discriminating unfamiliar faces are, or at least may be, dissociable. It follows that higherlevel perceptual disability cannot serve as a y~nrral explanation of the clinical symptom although it may apply validly to some cases. Some (but by no means all) prosopagnosic patients complain that faces appear to them to be “distorted”, “contorted”. “warped”, or “flat” and this has been called a “metamorphopsic form” of facial agnosia by Hecaen and Angelergues (1962). However, it is doubtful whether aberrations of this type are a major determinant of the failure to recognize familiar faces for. as Htcaen and Angelergues themselves point out, facial recognition in these patients is often less impaired than in those who do not experience these visuoperceptive distortions. Moreover, as attested to by more than a score of case reports, metamorphopsia as a primary complaint is rarely accompanied by facial agnosia. The case of De Renzi rt al. (1968) did show a concomitance of facial agnosia and quite severe disability in the discrimination of unfamiliar faces and it seemed reasonable to explain the clinical symptom in terms of the visuoperceptive disability. HowJ. nr?C-of. ser.. 197’.
IS: 167 177
PROSOPAGNOSIA
171
AND FACIAL DISCRIMINATION
ever, aside from the fact that three subsequent
case reports
have now shown
that
prosopagnosia may occur in the absence ofthe perceptual disability, there.is the further consideration that most patients with extremely severe impairment in the discrimination of unfamiliar faces show no signs of facial agnosia. If then facial agnosia is not easily ascribed to visuoperceptive defects, the question arises as to what the underlying disability (or disabilities) may be. A definitive answer cannot be given but it seems likely that the primary factor may be of an associative nature
involving
impairment
in the integration
of current
with past experience.
Their
findings led Warrington and James (1967) not only to draw a distinction between impaired discrimination of unfamiliar faces and prosopagnosia but also to speculate that the latter, as well as the associated
disability
in recognizing
celebrities,
represents
a partial form of the “amnesic syndrome”. The finding that the prosopagnosia of our patient showed itself within a context of a rather mild yet pervasive loss of memory for the recent past fits in with this hypothesis. In any event, if the disability is classitied as a form of agnosia (some justification for which can be derived from the fact that it is specifically associated with a single sensory modality). it is an agnosia of an “associative” rather than “apperceptive” type (Lissauer 1890). The fact that impairment in the perception and identification of unfamiliar faces has been found to be dissociated from facial agnosia has had interesting consequences since the purely perceptual disability has proved to be of neurological interest in its own right. It is closely associated with disease of the right hemisphere and at the same time it is clear that a basic sensory defect (e.g. poor visual acuity, visual field defect) or general mental impairment cannot be invoked as adequate explanations for its appearance. A likely hypothesis is that a “higher order” visuoperceptive defect (i.e., impairment in the processing and integration of visual information) is responsible for failure on facial discrimination tasks as well as on other tasks (e.g. mixed figures. complex form discrimination) making the same demands on perceptual integration. For example, De Renzi and Spinnler (1966) found that defective facial recognition was associated with failure in discriminating abstract line drawings and concluded that impairment in visual discrimination and integration was responsible for both types of performance deficits. Similarly, Benton and Gordon (1971) have shown that facial discrimination is particularly closely related to the ability to discriminate differential brightness patterns and they interpret this result as indicating that pattern discrimination involving the utilization of differences in brightness as cues is an important component of facial recognition. Another possibility is that there does indeed exist a distinctive primary ability to recognize faces which is subserved by neural mechanisms in the parieto-occipital area of the right hemisphere (or perhaps of both hemispheres). This rather extreme hypothesis, advanced by Bodamer (1947) and others, would seem at first glance to be most improbable. However, it has in fact received some empirical support in recent studies (Tzavaras et al. 1970; Yin 1970) which suggests that there is something “special” about facial recognition and that it may be useful and meaningful to make a distinction between this particular form of visual discrimination and other tasks requiring the processing and integration of visual information.
J. neural. Sri.. 1972, 15: 167-172
172
A. L. BENTON,
M. W. VAN ALLEN
SUMMARY
The relations between prosopagnosia and the ability to discriminate unfamiliar faces are reviewed and the performance of a prosopagnosic patient on a facial discrimination test as well as on other tasks requiring the processing and integration of visual information is described. The finding that this patient showed essentially normal ability
to discriminate
unfamiliar
faces supports
the contention
that prosopagnosia
cannot be solely explained in terms of a general visuoperceptive impairment. The present state of our understanding of the disabilities underlying both prosopagnosia and defective discrimination of unfamiliar fzces is discussed. REFERENCES Ass~I.. G. (1969) Regression des troubles de la reconnaissance des physionomies et de la memoire topogrnphique cher un malade opCrC d’un htmatome intracerebral paritto-temporal droit. Rw. wurol.. 121: 184185. BEXTON. A. L. AND M. W. VAN ALLEN (1968) Impairment in facial recognition in patients with cerebral disease. Cortex, 4: 344 358. BENTON, A. L. AND M. C. G~RU~N (1971) Correlates of facial recognition. ~rc~ns. Amcr ncwol. A,.\.. 96: In press. B~NTON. A. L., M. W. VAN ALLEN AND M. L. Fo~;~L (1964) Temporal orientation in cerebral disease. J. mv~. ment. Dir., 139: 1 lo- 119. BODAMER. J. (1947) Die Prosop-Agnosie, Arch. Pslxhirrr. Nercrnkr.. 179: 6654. DE RI:NZI, E. AND H. SPINNLER (1966) Facial recognition in brain-damaged patients. l’vw~o/o~/J~i .Mirrmwp~. 16: 1455152. DF RFNZI. E., P. FAGLI~NI AND H. SPINNLER (1968) The performance of patients with unilateral brain damage on face recognition tasks, Cwt~, 4: 17-34. H~CAEN, H. AND R. ANGELERCUES (1962) Agnosia for faces (prosopagnosia), Ard. Ncvm~l. /Chtc ), 7: 92~ 100. LISSAUFR, W. (1890) Ein Fall von Seelenblindheit nebst einen Beitrag zur Theorie Llerselben. .-lrc~h. P.wchiof. Nerwtzkr., 21 : 222. 270. RONDOT. P.. A. TZAVARAS AND R. GARUN (1967) Sur un cas de prosopagnosie persistant depuis quince ans, Rev. neural., 117: 424428. T~AV~RAS, A.. H. HBCAEN AND H. LE BRAS (1970) Le probltme de la specificite du deficit de la reconnaissance du visage humain lors des lesions htmispheriques unilattrales. Neurops!,cho/o!/i~/~ 8 : 403 416. WARRI~GTON, E. K. AND M. JAMES (1967) An experimental investigation of facial recognition in patients with unilateral cerebral lesions. Corze.u. 3 : 3 177326. YIX. R. K. (1970) Face recognition by brain-injured patients : a dissociable abihty? iVc/r~,,/~s~.(,ho/~,c/itr.X : 395402.
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I5 : I67 I72