The neuropsychological evaluation of face identity recognition

Facial identity recognition (FIR) is arguably the ultimate form of recognition for the adult human brain. Even if the term prosopagnosia is reserved for exceptionally rare brain-damaged cases with a category-specific abrupt loss of FIR at adulthood, subjective and objective impairments or difficulties of FIR are common in the neuropsychological population. Here we provide a critical overview of the evaluation of FIR both for clinicians and researchers in neuropsychology. FIR impairments occur following many causes that should be identified objectively by both general and specific, behavioral and neural examinations. We refute the commonly used dissociation between perceptual and memory deficits/tests for FIR, since even a task involving the discrimination of unfamiliar face images presented side-by-side relies on cortical memories of faces in the right-lateralized ventral occipito-temporal cortex. Another frequently encountered confusion is between specific deficits of the FIR function and a more general impairment of semantic memory (of people), the latter being most often encountered following anterior temporal lobe damage. Many computerized tests aimed at evaluating FIR have appeared over the last two decades, as reviewed here. However, despite undeniable strengths, they often suffer from ecological limitations, difficulties of instruction, as well as a lack of consideration for processing speed and qualitative information. Taking into account these issues, a recently developed behavioral test with natural images manipulating face familiarity, stimulus inversion, and correct response times as a key variable appears promising. The measurement of electroencephalographic (EEG) activity in the frequency domain from fast periodic visual stimulation also appears as a particularly promising tool to complete and enhance the neuropsychological assessment of FIR.

Binocular rivalry reveals differential face processing in congenital prosopagnosia

Congenital Prosopagnosia (CP) is an innate impairment in face perception with heterogeneous characteristics. It is still unclear if and to what degree holistic processing of faces is disrupted in CP. Such disruption would be expected to lead to a focus on local features of the face. In this study, we used binocular rivalry (BR) to implicitly measure face perception in conditions that favour holistic or local processing. The underlying assumption is that if stimulus saliency affects the perceptual dominance of a given stimulus in BR, one can deduce how salient a stimulus is for a given group (here: participants with and without CP) based on the measured perceptual dominance. A further open question is whether the deficit in face processing in CP extends to the processing of the facial display of emotions. In experiment 1, we compared predominance of upright and inverted faces displaying different emotions (fearful, happy, neutral) vs. houses between participants with CP (N = 21) and with normal face perception (N = 21). The results suggest that CP observers process emotions in faces automatically but rely more on local features than controls. The inversion of faces, which is supposed to disturb holistic processing, affected controls in a more pronounced way than participants with CP. In experiment 2, we introduced the Thatcher effect in BR by inverting the eye and mouth regions of the presented faces in the hope of further increasing the effect of face inversion. However, our expectations were not borne out by the results. Critically, both experiments showed that inversion effects were more pronounced in controls than in CP, suggesting that holistic face processing is less relevant in CP. We find BR to be a useful implicit test for assessing visual processing specificities in neurological participants.

Investigating the Influence of Autism Spectrum Traits on Face Processing Mechanisms in Developmental Prosopagnosia

Autism traits are common exclusionary criteria in developmental prosopagnosia (DP) studies. We investigated whether autism traits produce qualitatively different face processing in 43 DPs with high vs. low autism quotient (AQ) scores. Compared to controls (n = 27), face memory and perception were similarly deficient in the high- and low-AQ DPs, with the high-AQ DP group additionally showing deficient face emotion recognition. Task-based fMRI revealed reduced occipito-temporal face selectivity in both groups, with high-AQ DPs additionally demonstrating decreased posterior superior temporal sulcus selectivity. Resting-state fMRI showed similar reduced face-selective network connectivity in both DP groups compared with controls. Together, this demonstrates that high- and low-AQ DP groups have very similar face processing deficits, with additional facial emotion deficits in high-AQ DPs.

Alcohol Use Predicts Face Perception Impairments and Difficulties in Face Recognition

Background: Risky alcohol use is related to a variety of cognitive impairments, including memory and visuo-perceptual difficulties. Remarkably, no prior work has assessed whether usage of alcohol can predict difficulties perceiving facial identity. Objectives: Therefore, this study aimed to investigate whether riskier alcohol consumption predicted impairments in face perception and self-reported difficulties in face recognition. Results: Participants (N = 239, male = 77) were over 18 years old and had normal or corrected-to-normal vision. Alcohol use was assessed using the Alcohol Use Disorder Identification Test (AUDIT), while face recognition difficulties were determined by the 20-item Prosopagnosia Index questionnaire (PI20). A subsample of participants (N = 126, male = 51) completed the Cambridge Face Perception task (CFPT) to assess their face perception ability. Multiple linear regressions showed significant models of prediction on both face perception and face recognition when considering AUDIT score and age as predictors. Conclusion: This study suggested, for the first time, that risky alcohol use predicts both poorer visuo-perceptual processing for faces and self-reported difficulties in face recognition.

Anatomical and neurophysiological basis of face recognition

Face recognition is a highly developed and efficient human function that involves multiple neural networks. A main pathway links the occipital cortex, where an occipital face area (OFA) has been identified, to a fusiform face area (FFA) in the fusiform gyrus, which plays a critical role in face recognition. This core pathway deals with invariant aspects of the face. Another pathway, including the superior temporal sulcus, is involved in the perception of more changeable aspects of the face such as gaze orientation, face expression and lip movements. It has been defined by some authors as a "third pathway of visual recognition", i.e. a lateral pathway in addition to the "what" and "where" pathways. It deals with sociocognitive aspects of face perception. Many other accessory functional systems are connected to the core system of visual recognition to act in concert with it: the intraparietal sulcus (for the management of spatial attention), the primary auditory cortex (prelexical perception of speech), the amygdala, the insula and the limbic system (perception of emotions), the anterior temporal pole (access to the identity of the individual, his name, biographical information), etc. Functional brain imaging has made remarkable progress in the understanding of face perception, which in the early years was limited to the description of single cases of brain-damaged patients. This progress has made it possible to better analyse the many face recognition disorders, sometimes subtle, other times confusing, observed in human pathology.

People have modest, not good, insight into their face recognition ability: a comparison between self-report questionnaires

Whether people have insight into their face recognition ability has been intensely debated in recent studies using self-report measures. Although some studies showed people’s good insight, other studies found the opposite. The discrepancy might be caused by the difference in the questionnaire used and/or the bias induced using an extreme group such as suspected prosopagnosics. To resolve this issue, we examined the relationship between the two representative self-report face recognition questionnaires (Survey, N = 855) and then the extent to which the questionnaires differ in their relationship with face recognition performance (Experiment, N = 180) in normal populations, which do not include predetermined extreme groups. We found a very strong correlation (r = 0.82), a dominant principal component (explains > 90% of the variance), and comparable reliability between the questionnaires. Although these results suggest a strong common factor underlying them, the residual variance is not negligible (33%). Indeed, the follow-up experiment showed that both questionnaires have significant but moderate correlations with actual face recognition performance, and that the correlation was stronger for the Kennerknecht’s questionnaire (r =  − 0.38) than for the PI20 (r =  − 0.23). These findings not only suggest people’s modest insight into their face recognition ability, but also urge researchers and clinicians to carefully assess whether a questionnaire is suitable for estimating an individual’s face recognition ability.

Training face perception in developmental prosopagnosia through perceptual learning

BACKGROUND

Recent work has shown that perceptual learning can improve face discrimination in subjects with acquired prosopagnosia.

OBJECTIVE

In this study, we administered the same program to determine if such training would improve face perception in developmental prosopagnosia.

METHOD

We trained ten subjects with developmental prosopagnosia for several months with a program that required shape discrimination between morphed facial images, using a staircase procedure to keep training near each subject's perceptual threshold. To promote ecological validity, training progressed from blocks of neutral faces in frontal view through increasing variations in view and expression. Five subjects did 11 weeks of a control television task before training, and the other five were re-assessed for maintenance of benefit 3 months after training.

RESULTS

Perceptual sensitivity for faces improved after training but did not improve after the control task. Improvement generalized to untrained expressions and views of these faces, and there was some evidence of transfer to new faces. Benefits were maintained over three months. Training also led to improvements on standard neuropsychological tests of short-term familiarity, and some subjects reported positive effects in daily life.

CONCLUSION

We conclude that perceptual learning can lead to persistent improvements in face discrimination in developmental prosopagnosia. The strong generalization suggests that learning is occurring at the level of three-dimensional representations with some invariance for the dynamic effects of expression.

Prosopagnosia in Biographies and Autobiographies

Prosopagnosia is a selective impairment of the visual learning and recognition of faces. The congenital type, which is not accompanied by detectable brain damage or malformation, was recently found to be far more common than previously known. Therefore, one should expect that at least a few biographies or autobiographies would reveal a prosopagnosia. In this paper we present an autobiography and a biography describing five cases of congenital prosopagnosia. These biographic descriptions of prosopagnosia add further evidence to the assumption that the congenital type of prosopagnosia is not a rare condition, and not as socially crippling as one might expect.

[Prosopagnosia and facial expression recognition]

This paper reviews clinical neuropsychological studies that have indicated that the recognition of a person's identity and the recognition of facial expressions are processed by different cortical and subcortical areas of the brain. The fusiform gyrus, especially the right fusiform gyrus, plays an important role in the recognition of identity. The superior temporal sulcus, amygdala, and medial frontal cortex play important roles in facial-expression recognition. Both facial recognition and facial-expression recognition are highly intellectual processes that involve several regions of the brain.

Preference for normal, reversed or chimeric self-faces with neutral emotional expression in patients with schizophrenia and control subjects

OBJECTIVES

Self-face recognition is one of the most distinctive features in human beings. Disturbances of self-face recognition in people with schizophrenia may reflect the underlying neurobiological and psychological factors of the disorder. Our aim was to establish whether differences in preference for the similarity to the true self-face appearance could be found between patients with schizophrenia and a matched control group.

SUBJECTS AND METHODS

14 right-handed patients with schizophrenia and 14 control subjects were enrolled. Subjects were photographed, the pictures were converted to black and white, halved vertically, and four faces were used: normal face (NF), mirrored face (MF), face composed from two left halves of the face (LLF) and from two right halves of face (RRF). Four pairs of faces were exposed to subjects and they chose which they felt was closest to their true appearance.

RESULTS

No significant differences for preference were found between the patients and control subjects. Post-hoc analysis of the pooled groups showed a significant difference for preference of NF vs. RRF (20 vs. 8 probands; χ2=5.14, df=1, p<0.05). 18 subjects from the two groups did not change the right-left visual field focus through all four exposures.

CONCLUSIONS

The absence of significant differences for preference for true self-image between schizophrenia patients and control subjects might show that self-face recognition is of little importance from the evolutionary perspective. Additional measurements such as eye-tracking control and random multiple projections of the same pairs of faces would contribute to a more thorough interpretation of the findings in future studies of similar design.

Training with own-race faces can improve processing of other-race faces: evidence from developmental prosopagnosia

Faces of one's own race are discriminated and recognized more accurately than faces of an other race (other-race effect - ORE). Studies have employed several methods to enhance individuation and recognition of other-race faces and reduce the ORE, including intensive perceptual training with other-race faces and explicitly instructing participants to individuate other-race faces. Unfortunately, intensive perceptual training has shown to be specific to the race trained and the use of explicit individuation strategies, though applicable to all races, can be demanding of attention and difficult to consistently employ. It has not yet been demonstrated that a training procedure can foster the automatic individuation of all other-race faces, not just faces from the race trained. Anecdotal evidence from a training procedure used with developmental prosopagnosics (DPs) in our lab, individuals with lifelong face recognition impairments, suggests that this may be possible. To further test this idea, we had five Caucasian DPs perform ten days of configural face training (i.e. attending to small spacing differences between facial features) with own-race (Caucasian) faces to see if training would generalize to improvements with other-race (Korean) faces. To assess training effects and localize potential effects to parts-based or holistic processing, we used the part-whole task using Caucasian and Korean faces (Tanaka, J. W., Kiefer, M., & Bukach, C. M. (2004). A holistic account of the own-race effect in face recognition: evidence from a cross-cultural study. Cognition, 93(1), B1-9). Results demonstrated that after training, DPs showed a disproportionate improvement in holistic processing of other-race faces compared to own-race faces, reducing their ORE. This suggests that configural training with own-race faces boosted DPs' general configural/holistic attentional resources, which they were able to apply to other-race faces. This provides a novel method to reduce the ORE and supports more of an attentional/social-cognitive model of the ORE rather than a strictly expertise model.

Naming faces: a multidisciplinary and integrated review

Naming faces is a common area of study from a wide range of perspectives in social sciences, including cognitive psychology and several branches of cognitive neuroscience. This paper provides a comprehensive review of the cognitive models that have been proposed to explain the diverse aspects of face naming, taking into account face processing and language production models. In addition, a review of the neuroscientific data from event-related potential studies (when) and functional neuroimaging studies (where) is presented. Thus, an integrated view of the cognitive models and the data relating the different processes involved in naming faces to the brain activity is provided.

Three cases of developmental prosopagnosia from one family: detailed neuropsychological and psychophysical investigation of face processing

A number of reports have documented that developmental prosopagnosia (DP) can run in families, but the locus of the deficits in those cases remains unclear. We investigated the perceptual basis of three cases of DP from one family (67 year-old father FA, and two daughters, 39 year-old D1 and 34 year-old D2) by combining neuropsychological and psychophysical methods. Neuropsychological tests involving natural facial images demonstrated significant face recognition deficits in the three family members. All three members showed normal facial expression recognition and face detection, and two of them (D2, FA) performed well on within-class object recognition tasks. These individuals were then examined in a series of psychophysical experiments. Intermediate form vision preceding face perception was assessed with radial frequency (RF) patterns. Normal discrimination of RF patterns in these individuals indicates that their face recognition difficulties are higher in the cortical form vision hierarchy than the locus of contour shape processing. Psychophysical experiments requiring discrimination and memory for synthetic faces aimed to quantify their face processing abilities and systematically examine the representation of facial geometry across viewpoints. D1 showed deficits in perceiving geometric information from the face at a given view. D2's impairments seem to arise in later face processing stages involving transferring view-dependent descriptions into a view-invariant representation. FA performed poorly on face learning and recognition relative to the age-appropriate controls. These cases provide evidence for familial transmission of high-level visual recognition deficits with normal intermediate-level form vision.

Overview of impaired facial affect recognition in persons with traumatic brain injury

PRIMARY OBJECTIVE

To review the literature of affect recognition for persons with traumatic brain injury (TBI). It is suggested that impairment of affect recognition could be a significant problem for the TBI population and treatment strategies are recommended based on research for persons with autism.

MAIN OUTCOMES AND RESULTS

Research demonstrates that persons with TBI often have difficulty determining emotion from facial expressions. Studies show that poor interpersonal skills, which are associated with impaired affect recognition, are linked to a variety of negative outcomes. Theories suggest that facial affect recognition is achieved by interpreting important facial features and processing one's own emotions. These skills are often affected by TBI, depending on the areas damaged. Affect recognition impairments have also been identified in persons with autism. Successful interventions have already been developed for the autism population. Comparable neuroanatomical and behavioural findings between TBI and autism suggest that treatment approaches for autism may also benefit those with TBI.

CONCLUSIONS

Impaired facial affect recognition appears to be a significant problem for persons with TBI. Theories of affect recognition, strategies used in autism and teaching techniques commonly used in TBI need to be considered when developing treatments to improve affect recognition in persons with brain injury.

The delusional misidentification syndromes: strange, fascinating, and instructive

The delusional misidentification syndromes (Capgras' syndrome, Frégoli syndrome, intermetamorphosis syndrome, syndrome of subjective doubles) are rare psychopathologic phenomena that occur primarily in the setting of schizophrenic illness, affective disorder, and organic illness. They are grouped together because they often co-occur and interchange, and their basic theme is the concept of the double (sosie). They are distinguished as hypoidentifications (Capgras' syndrome) and hyperidentifications (the other three syndromes). In this review, we present the basic hypotheses that have been put forward to explain these syndromes and propose that the appearance of these syndromes must alert physicians to investigate the existence of possible organic contributions.

Psychosocial consequences of developmental prosopagnosia: a problem of recognition

OBJECTIVE

To provide the first systematic in-depth description of the consequences of developmental prosopagnosia (DP; 'face blindness') for psychosocial functioning and occupational disability, in order to determine what kind of professional intervention may be needed.

METHODS

Semi-structured telephone interviews were carried out with 25 people whose self-reports of face recognition problems were confirmed by impaired scores on the Cambridge Face Recognition Test. Thematic analysis was used to inductively identify and understand common psychosocial consequences of DP.

RESULTS

All participants described recurrent and sometimes traumatic social interaction difficulties caused by recognition problems, such as failing to recognize close friends, work colleagues, and family members. These problems often led to chronic anxiety about offending others and feelings of embarrassment, guilt, and failure. Most participants described some degree of fear and avoidance of social situations in which face recognition was important, including family and social gatherings, and meetings at work. Long-term consequences could include dependence on others, a restricted social circle, more limited employment opportunities, and loss of self-confidence.

CONCLUSION

The potential for negative psychosocial consequences and occupational disability posed by DP is as great as that posed by conditions which are currently afforded professional recognition and support, such as stuttering and dyslexia. Wider recognition of the problems prosopagnosia can cause could reduce anxiety about social interaction difficulties by making it easier to explain and justify recognition problems to other people, including employers. Greater professional awareness could facilitate detection and referral of those requiring support with coping with social interactions.

The contribution of the fusiform gyrus and superior temporal sulcus in processing facial attractiveness: neuropsychological and neuroimaging evidence

Current cognitive models suggest that the processing of dynamic facial attributes, including social signals such as gaze direction and facial expression, involves the superior temporal sulcus, whereas the processing of invariant facial structure such as the individuals' identity involves the fusiform face area. Where facial attractiveness, a social signal that may emerge from invariant facial structure, is processed within this dual-route model of face perception is uncertain. Here, we present two studies. First, we investigated the explicit judgments of facial attractiveness and attractiveness-motivated behavior in patients with acquired prosopagnosia, a deficit in familiar face recognition usually associated with damage to medial occipitotemporal cortex. We found that both abilities were impaired in these patients, with some weak residual ability for attractiveness judgments found only in those patients with unilateral right occipitotemporal or bilateral anterior temporal lesions. Importantly, deficits in attractiveness perception correlated with the severity of the face recognition deficit. Second, we performed a functional magnetic resonance imaging study in healthy subjects that included an implicit and explicit processing of facial attractiveness. We found increased neural activity when explicitly judging facial attractiveness within a number of cortical regions including the fusiform face area, but not the superior temporal sulcus, indicating a potential contribution of the fusiform face area to this judgment. Thus, converging neuropsychological and neuroimaging evidence points to a critical role of the inferior occipitotemporal cortex in the processing of facial attractiveness.

The Philadelphia Face Perception Battery

The Philadelphia Face Perception Battery (PFPB) tests four aspects of face perception: discrimination of facial similarity, attractiveness, gender, and age. Calibration with 116 neurologically intact subjects yielded average performance of approximately 90%. Across subjects, there was a low correlation (<0.22) in performance between the tests (with the exception of the attractiveness and age discrimination tests) suggesting that the tests measure independent aspects of face perception. There were modest effects of subject demographic factors upon performance, and test-retest reliability scores (between 0.37 and 0.75) were comparable to other neuropsychological batteries. Modification of the stimuli to obscure internal facial features lowered performance on the age, gender, and attractiveness discrimination tests between 2 and 4 standard deviations. The clinical sensitivity of the battery was demonstrated by testing a patient with acquired prosopagnosia. She showed performance impairments of between 2 and 4 standard deviations on all sub-tests. The PFPB is freely available for non-commercial use.

Scan patterns during the processing of facial identity in prosopagnosia

The scan patterns of ocular fixations made by prosopagnosic patients while they attempt to identify faces may provide insights into how they process the information in faces. Contrasts between their scanning of upright versus inverted faces may index the presence of a hypothesized orientation-dependent expert mechanism for processing faces, while contrasts between their scanning of familiar versus novel faces may index the influence of residual facial memories on their search for meaningful facial information. We recorded the eye movements of two prosopagnosics while they viewed faces. One patient, with acquired prosopagnosia from a right occipitotemporal lesion, showed degraded orientation effects but still with a normal distribution of fixations to more salient facial features. However, the dynamics of his global scan patterns were more chaotic for novel faces, suggesting degradation of an internal facial schema, and consistent with other evidence of impaired face configuration perception in this patient. His global scan patterns for famous faces differed from novel faces, suggesting the influence of residual facial memories, as indexed previously by his relatively good imagery for famous faces. The other patient, with a developmental prosopagnosia, showed anomalous orientation effects, abnormal distribution of fixations to less salient regions, and chaotic global scan patterns, in keeping with a more severe loss of face-expert mechanisms. The effects of fame on her scanning were weaker than those in the first subject and non-existent in her global scan patterns. We conclude that scan patterns in prosopagnosia can both reflect the loss of orientation-dependent expert mechanisms and index the covert influence of residual facial memories. In these two subjects the scanning data were consistent with other results from tests of configuration perception, imagery, and covert recognition.

[Neural mechanisms of facial recognition]

We review recent researches in neural mechanisms of facial recognition in the light of three aspects: facial discrimination and identification, recognition of facial expressions, and face perception in itself. First, it has been demonstrated that the fusiform gyrus has a main role of facial discrimination and identification. However, whether the FFA (fusiform face area) is really a special area for facial processing or not is controversial; some researchers insist that the FFA is related to 'becoming an expert' for some kinds of visual objects, including faces. Neural mechanisms of prosopagnosia would be deeply concerned to this issue. Second, the amygdala seems to be very concerned to recognition of facial expressions, especially fear. The amygdala, connected with the superior temporal sulcus and the orbitofrontal cortex, appears to operate the cortical function. The amygdala and the superior temporal sulcus are related to gaze recognition, which explains why a patient with bilateral amygdala damage could not recognize only a fear expression; the information from eyes is necessary for fear recognition. Finally, even a newborn infant can recognize a face as a face, which is congruent with the innate hypothesis of facial recognition. Some researchers speculate that the neural basis of such face perception is the subcortical network, comprised of the amygdala, the superior colliculus, and the pulvinar. This network would relate to covert recognition that prosopagnosic patients have.

[Neural mechanisms of facial recognition]

We review recent researches in neural mechanisms of facial recognition in the light of three aspects: facial discrimination and identification, recognition of facial expressions, and face perception in itself. First, it has been demonstrated that the fusiform gyrus has a main role of facial discrimination and identification. However, whether the FFA (fusiform face area) is really a special area for facial processing or not is controversial; some researchers insist that the FFA is related to 'becoming an expert' for some kinds of visual objects, including faces. Neural mechanisms of prosopagnosia would be deeply concerned to this issue. Second, the amygdala seems to be very concerned to recognition of facial expressions, especially fear. The amygdala, connected with the superior temporal sulcus and the orbitofrontal cortex, appears to operate the cortical function. The amygdala and the superior temporal sulcus are related to gaze recognition, which explains why a patient with bilateral amygdala damage could not recognize only a fear expression; the information from eyes is necessary for fear recognition. Finally, even a newborn infant can recognize a face as a face, which is congruent with the innate hypothesis of facial recognition. Some researchers speculate that the neural basis of such face perception is the subcortical network, comprised of the amygdala, the superior colliculus, and the pulvinar. This network would relate to covert recognition that prosopagnosic patients have.

Prosopagnosia Without Apparent Cause: Overview and Diagnosis of Six Cases

We compared six cases of congenital prosopagnosia to unimpaired participants using standardized test batteries, tailor-made experimental paradigms, and clinical questionnaires. Every prosopagnosic participant displayed deficits in recognizing famous faces and retaining novel faces over short periods of time. Other aspects of face perception such as judgment of emotional expression, speech reading and memory for faces and names were impaired to a lesser degree or only in single cases. No evidence was found for general visual deficits or social dysfunctions. Two of our six cases are first order relatives, and a further three report first-order relatives suffering from prosopagnosic symptoms. The results are in line with the idea of a genetic component to congenital prosopagnosia.

Les visages et leurs émotions

Faces represent a crucial vector of interhuman communication. The message transmitted by the face has multiple features. Recognition of each feature can be impaired independently or in combination with others. In order to understand the behavioral consequences of such impairments, which can be a major social handicap, we first must specify the neural networks involved in face recognition. We propose in this first part to present the systems involved in face recognition, in particular the question of identity and prosopagnosia. Different neural networks are indeed implicated in the recognition of invariant facial features such as identity, gender, ethnicity, and recognition of variant features like facial expression and eye gaze. This paper is illustrated by some of our scalp and intracranial electrophysiological studies performed in humans allowing us to describe some aspects of face recognition dynamics combining an excellent spatial and temporal resolution. Intracranial recordings were performed in drug refractory epileptical patients implanted with depth electrodes. These studies demonstrate that numerous deep brain and cortical structures participate early and sometimes in a sustained manner in face recognition.

Functional and structural deficits in brain regions subserving face perception in schizophrenia

OBJECTIVE

Schizophrenia impairs many cognitive functions, including face perception. Veridical face perception is critical for social interaction, including distinguishing friend from foe and familiar from unfamiliar faces. The main aim of this study was to determine whether patients with schizophrenia show less activation in neural networks related to face processing, compared with healthy subjects, and to investigate the relationships between this functional abnormality and anatomical abnormalities in the fusiform gyrus shown with magnetic resonance imaging (MRI).

METHOD

Twenty male chronic schizophrenia patients and 16 healthy comparison subjects matched with the patients for age, gender, handedness, and parental socioeconomic status underwent high-spatial-resolution MRI. Event-related potentials elicited by images of faces, cars, and hands were recorded in a separate session.

RESULTS

Compared to the healthy subjects, the patients with schizophrenia showed bilateral N170 amplitude reduction in response to images of faces but not to images of other objects. The patients also had smaller bilateral anterior and posterior fusiform gyrus gray matter volumes, compared to the healthy subjects. In addition, right posterior fusiform gyrus volume was significantly correlated with N170 amplitude measured at the right posterior temporal electrode site in response to images of faces in the schizophrenia patients but not in the healthy comparison subjects.

CONCLUSIONS

The results provide evidence for deficits in the early stages of face perception in schizophrenia. The association of these deficits with smaller fusiform gyrus volume in patients with schizophrenia, relative to healthy subjects, suggests that the fusiform gyrus is the site of a defective anatomical substrate for face processing in schizophrenia.

The Cambridge Face Memory Test: Results for neurologically intact individuals and an investigation of its validity using inverted face stimuli and prosopagnosic participants

The two standardized tests of face recognition that are widely used suffer from serious shortcomings [Duchaine, B. & Weidenfeld, A. (2003). An evaluation of two commonly used tests of unfamiliar face recognition. Neuropsychologia, 41, 713-720; Duchaine, B. & Nakayama, K. (2004). Developmental prosopagnosia and the Benton Facial Recognition Test. Neurology, 62, 1219-1220]. Images in the Warrington Recognition Memory for Faces test include substantial non-facial information, and the simultaneous presentation of faces in the Benton Facial Recognition Test allows feature matching. Here, we present results from a new test, the Cambridge Face Memory Test, which builds on the strengths of the previous tests. In the test, participants are introduced to six target faces, and then they are tested with forced choice items consisting of three faces, one of which is a target. For each target face, three test items contain views identical to those studied in the introduction, five present novel views, and four present novel views with noise. There are a total of 72 items, and 50 controls averaged 58. To determine whether the test requires the special mechanisms used to recognize upright faces, we conducted two experiments. We predicted that controls would perform much more poorly when the face images are inverted, and as predicted, inverted performance was much worse with a mean of 42. Next we assessed whether eight prosopagnosics would perform poorly on the upright version. The prosopagnosic mean was 37, and six prosopagnosics scored outside the normal range. In contrast, the Warrington test and the Benton test failed to classify a majority of the prosopagnosics as impaired. These results indicate that the new test effectively assesses face recognition across a wide range of abilities.

Perceptual Expertise Effects Are Not All or None: Spatially Limited Perceptual Expertise for Faces in a Case of Prosopagnosia

We document a seemingly unique case of severe prosopagnosia, L. R., who suffered damage to his anterior and inferior right temporal lobe as a result of a motor vehicle accident. We systematically investigated each of three factors associated with expert face recognition: fine-level discrimination, holistic processing, and configural processing (Experiments 1-3). Surprisingly, L. R. shows preservation of all three of these processes; that is, his performance in these experiments is comparable to that of normal controls. However, L. R. is only able to apply these processes over a limited spatial extent to the fine-level detail within faces. Thus, when the location of a given change is unpredictable (Experiment 3), L. R. exhibits normal detection of features and spatial configurations only for the lower half of each face. Similarly, when required to divide his attention over multiple face features, L. R. is able to determine the identity of only a single feature (Experiment 4). We discuss these results in the context of forming a better understanding of prosopagnosia and the mechanisms used in face recognition and visual expertise. We conclude that these mechanisms are not “all-or-none”, but rather can be impaired incrementally, such that they may remain functional over a restricted spatial area. This conclusion is consistent with previous research suggesting that perceptual expertise is acquired in a spatially incremental manner [Gauthier, I., & Tarr, M. J. Unraveling mechanisms for expert object recognition: Bridging brain activity and behavior. Journal of Experimental Psychology: Human Perception & Performance, 28, 431-446, 2002].

The fusiform face area is not sufficient for face recognition: Evidence from a patient with dense prosopagnosia and no occipital face area

We tested functional activation for faces in patient D.F., who following acquired brain damage has a profound deficit in object recognition based on form (visual form agnosia) and also prosopagnosia that is undocumented to date. Functional imaging demonstrated that like our control observers, D.F. shows significantly more activation when passively viewing face compared to scene images in an area that is consistent with the fusiform face area (FFA) (p < 0.01). Control observers also show occipital face area (OFA) activation; however, whereas D.F.'s lesions appear to overlap the OFA bilaterally. We asked, given that D.F. shows FFA activation for faces, to what extent is she able to recognize faces? D.F. demonstrated a severe impairment in higher level face processing--she could not recognize face identity, gender or emotional expression. In contrast, she performed relatively normally on many face categorization tasks. D.F. can differentiate faces from non-faces given sufficient texture information and processing time, and she can do this is independent of color and illumination information. D.F. can use configural information for categorizing faces when they are presented in an upright but not a sideways orientation and given that she also cannot discriminate half-faces she may rely on a spatially symmetric feature arrangement. Faces appear to be a unique category, which she can classify even when she has no advance knowledge that she will be shown face images. Together, these imaging and behavioral data support the importance of the integrity of a complex network of regions for face identification, including more than just the FFA--in particular the OFA, a region believed to be associated with low-level processing.

Reality confusion in spontaneous confabulation

A woman produced spontaneous confabulations after rupture of an anterior communicating artery aneurysm. She confused currently irrelevant with currently relevant information in implicit memory; confabulations about people concerned only new acquaintances; false reality could be induced by an intensive 5-minute discussion; and in a recognition task, she confused false repetitions in another modality with real item repetitions. The findings support the theory that the defect causing spontaneous confabulation precedes conscious memory processing.

Detailed Exploration of Face-related Processing in Congenital Prosopagnosia: 1. Behavioral Findings

We show that five individuals with congenital prosopagnosia (CP) are impaired at face recognition and discrimination and do not exhibit the normal superiority for upright over inverted faces despite intact visual acuity, low-level vision and intelligence, and in the absence of any obvious neural concomitant. Interestingly, the deficit is not limited to faces: The CP individuals were also impaired at discriminating common objects and novel objects although to a lesser extent than discriminating faces. The perceptual deficit may be attributable to a more fundamental visual processing disorder; the CP individuals exhibited difficulty in deriving global configurations from simple visual stimuli, even with extended exposure duration and considerable perceptual support in the image. Deriving a global configuration from local components is more critical for faces than for other objects, perhaps accounting for the exaggerated deficit in face processing. These findings elucidate the psychological mechanisms underlying CP and support the link between configural and face processing.

Perceptual functions in prosopagnosia

Some patients with prosopagnosia may have an apperceptive basis to their recognition defect. Perceptual abnormalities have been reported in single cases or small series, but the causal link of such deficits to prosopagnosia is unclear. Our goal was to identify candidate perceptual processes that might contribute to prosopagnosia, by subjecting several prosopagnosic patients to a battery of functions that may be necessary for accurate facial perception. We tested seven prosopagnosic patients. Three had unilateral right occipitotemporal lesions, two had bilateral posterior occipitotemporal lesions, and one had right anterior-to-occipital temporal damage along with a small left temporal lesion. These lesions all included the fusiform face area, in contrast to one patient with bilateral anterior temporal lesions. Most patients had impaired performance on face-matching tests and difficulty with subcategory judgments for non-face objects. The most consistent deficits in patients with lesions involving the fusiform face area were impaired perception of spatial relations in dot patterns and reduced contrast sensitivity in the 4 to 8 cycles deg(-1) range. Patients with bilateral lesions were impaired in saturation discrimination. Luminance discrimination was normal in all but two patients, and spatial resolution was uniformly spared. Curvature and line-orientation discrimination were impaired in only one patient, who also had the most difficulty with more basic-level object recognition. We conclude that deficits in luminance, spatial resolution, curvature, line orientation, and contrast at low spatial frequencies are unlikely to contribute to apperceptive prosopagnosia. More relevant may be contrast sensitivity at higher spatial frequencies and the analysis of object spatial structure. Deficits in these functions may impair perception of subtle variations in object shape, and may be one mechanism by which the recognition defect in prosopagnosia can extend to other classes of object subcategorization.

The covert priming effect of faces in prosopagnosia

BACKGROUND

There are many methods of testing covert face recognition in prosopagnosia, but it is not clear whether different types of covert recognition share a common mechanism.

OBJECTIVE

To determine whether direct forced-choice techniques and indirect face-priming methods yielded similar behavioral estimates of covert ability in a series of prosopagnosic patients.

METHODS

The authors tested seven control subjects and seven prosopagnosic patients. Six patients had an apperceptive prosopagnosia: one with childhood onset, three with bilateral lesions, and two with unilateral occipitotemporal lesions. The last had an associative prosopagnosia from bilateral anterior temporal lesions. The direct tests of covert function involved sorting faces by occupation or the forced choosing of which of two faces was famous with a name cue. The indirect test assessed name classification by occupation after priming with a facial stimulus.

RESULTS

In normal subjects, the chief priming effect was facilitation by the true face. In the six patients with apperceptive prosopagnosia, direct covert measures were correlated with the face-priming effect, with better covert ability in patients with unilateral posterior lesions. In the patient with associative prosopagnosia, there was a dissociation between excellent direct covert function and absent face priming.

CONCLUSIONS

Direct and indirect covert functions likely share similar mechanisms in patients with apperceptive prosopagnosia and may reflect residual activity in anterior and left hemispheric components of the normal face-processing network. However, face priming may be ineffectual in patients with severely degraded facial memories from anterior temporal damage. This may indicate a difference between residual patterns of face-related activity in associative and apperceptive prosopagnosia.

Exploring the role of motion in prosopagnosia: recognizing, learning and matching faces

HJA has been completely unable to recognize faces since suffering a stroke some 22 years ago. Previous research has shown that he is poor at judging expressions from static photographs of faces, but performs relatively normally at these judgements when presented with moving point-light patterns (Humphreys et al., 1993). Recent research with non-prosopagnosic participants has suggested a beneficial role for facial motion when recognizing familiar faces and learning new faces. Three experiments are reported that investigate the role of face motion for HJA when recognizing (Experiment 1), learning (Experiment 2) and matching faces (Experiment 3). The results indicate that HJA is unable to use face motion to explicitly recognize faces and is no better at learning names for moving faces than static ones. However, HJA is significantly better at matching moving faces for identity, an opposite pattern to that found with age-matched and undergraduate control participants. We suggest that HJA is not impaired at processing motion information but remains unable to use motion as a cue to identity.

Progressive prosopagnosia: Clinical and neuroimaging results

The authors report the longitudinal case study of a patient with the right temporal variant of frontotemporal lobar degeneration. His deficit, initially limited to visuoperceptual disturbances, progressed 2 years later to a severe semantic breakdown. Neuroimaging data indicate that the underlying degenerative process, initially confined to unimodal visual associative cortices, progressed along the ventral pathways to multimodal areas in charge of integrating knowledge from various modalities (the anterior temporal lobes).

Differences in olfactory and visual memory in patients with pathologically confirmed Alzheimer's disease and the Lewy body variant of Alzheimer's disease

Recognition and remote memory for odors, faces, and symbols were assessed in patients with pathologically confirmed Lewy body variant of Alzheimer's disease (LBV), patients with pathologically confirmed Alzheimer's disease (AD), and healthy elderly controls. On recognition memory tasks, LBV and AD patients showed significantly lower discriminability (d') than controls, particularly for olfactory stimuli. However no significant differences were found in the bias measure (c). When participants rated familiarity (a proposed measure of remote memory) of olfactory stimuli LBV and AD patients reported significantly lower familiarity than controls. Familiarity ratings were significantly lower in LBV patients than in AD patients for olfactory, but not for visual stimuli. Consistent with prior reports, the LBV patients showed significantly poorer odor thresholds than AD patients. The results suggest that recognition memory for olfactory stimuli is impaired in LBV and AD. However, patients with LBV are more impaired than patients with AD on tasks requiring remote memory for olfactory but not visual stimuli. The findings suggest that odor memory tasks may be useful in the assessment of LBV and AD.

Are patients with social developmental disorders prosopagnosic? Perceptual heterogeneity in the Asperger and socio-emotional processing disorders

It has been hypothesized that social developmental disorders (SDD) like autism, Asperger's disorder and the social-emotional processing disorder may be associated with prosopagnosic-like deficits in face recognition. We studied the ability to recognize famous faces in 24 adults with a variety of SDD diagnoses. We also measured their ability to discriminate changes in internal facial configuration, a perceptual function that is important in face recognition, and their imagery for famous faces, an index of their facial memory stores. We contrasted their performance with both healthy subjects and prosopagnosic patients. We also performed a cluster analysis of the SDD patients. One group of eight SDD subjects performed normally on all tests of face perception and recognition. The other 16 subjects were impaired in recognition, though most were better than prosopagnosic patients. One impaired SDD subgroup had poor perception of facial structure but relatively preserved imagery, resembling prosopagnosic patients with medial occipitotemporal lesions. Another subgroup had better perception than imagery, resembling one prosopagnosic with bilateral anterior temporal lesions. Overall, SDD subgroup membership by face recognition did not correlate with a particular SDD diagnosis or subjective ratings of social impairment. We conclude that the social disturbance in SDD does not invariably lead to impaired face recognition. Abnormal face recognition in some SDD subjects is related to impaired perception of facial structure in a manner suggestive of occipitotemporal dysfunction. Heterogeneity in the perceptual processing of faces may imply pathogenetic heterogeneity, with important implications for genetic and rehabilitative studies of SDD.

Normal pressure hydrocephalus manifesting as transient prosopagnosia, topographical disorientation, and visual objective agnosia

Usually, dementia, gait disturbance and urinary incontinence are an integral part of the clinical presentation of normal pressure hydrocephalus (NPH). However, NPH with transient visual cognitive disorders has not been reported previously. We herein describe an extremely rare case of NPH that presented with transient visual cognitive disorders and long lasting visual memory disturbances that subsided after CSF shunting. A 38-years-old man developed transient prosopagnosia, topographical disorientation, color vision disturbance, and visual objective agnosia that progressed over 5 years. Magnetic resonance images showed ventriculomegaly with ischemic lesions in the paraventricular deep white matter. ECD-SPECT showed a reduction of the cerebral blood flow (CBF) in the periventricular deep white matter. Three months after CSF shunting, the radiological findings normalized with dramatic improvement of the extremely rare symptoms.

Visual agnosia

The visual agnosias are an intriguing class of clinical phenomena that have important implications for current theories of high-level vision. Visual agnosia is defined as impaired object recognition that cannot be attributed to visual loss, language impairment, or a general mental decline. At least in some instances, agnostic patients generate an adequate internal representation of the stimulus but fail to recognize it. In this review, we begin by describing the classic works related to the visual agnosias, followed by a description of the major clinical variants and their occurrence in degenerative disorders. In keeping with the theme of this issue, we then discuss recent contributions to this domain. Finally, we present evidence from functional imaging studies to support the clinical distinction between the various types of visual agnosias.

Normal recognition of emotion in a prosopagnosic

In the leading model of face perception, facial identity and facial expressions of emotion are recognized by separate mechanisms. In this report, we provide evidence supporting the independence of these processes by documenting an individual with severely impaired recognition of facial identity yet normal recognition of facial expressions of emotion. NM, a 40-year-old prosopagnosic, showed severely impaired performance on five of six tests of facial identity recognition. In contrast, she performed in the normal range on four different tests of emotion recognition. Because the tests of identity recognition and emotion recognition assessed her abilities in a variety of ways, these results provide solid support for models in which identity recognition and emotion recognition are performed by separate processes.

A network of occipito-temporal face-sensitive areas besides the right middle fusiform gyrus is necessary for normal face processing

Neuroimaging studies have identified at least two bilateral areas of the visual extrastriate cortex that respond more to pictures of faces than objects in normal human subjects in the middle fusiform gyrus [the 'fusiform face area' (FFA)] and, more posteriorly, in the inferior occipital cortex ['occipital face area' (OFA)], with a right hemisphere dominance. However, it is not yet clear how these regions interact which each other and whether they are all necessary for normal face perception. It has been proposed that the right hemisphere FFA acts as an isolated ('modular') processing system for faces or that this region receives its face-sensitive inputs from the OFA in a feedforward hierarchical model of face processing. To test these proposals, we report a detailed neuropsychological investigation combined with a neuroimaging study of a patient presenting a deficit restricted to face perception, consecutive to bilateral occipito-temporal lesions. Due to the asymmetry of the lesions, the left middle fusiform gyrus and the right inferior occipital cortex were damaged but the right middle fusiform gyrus was structurally intact. Using functional MRI, we disclosed a normal activation of the right FFA in response to faces in the patient despite the absence of any feedforward inputs from the right OFA, located in a damaged area of cortex. Together, these findings show that the integrity of the right OFA is necessary for normal face perception and suggest that the face-sensitive responses observed at this level in normal subjects may arise from feedback connections from the right FFA. In agreement with the current literature on the anatomical basis of prosopagnosia, it is suggested that the FFA and OFA in the right hemisphere and their re-entrant integration are necessary for normal face processing.

A modulatory role for facial expressions in prosopagnosia

Brain-damaged patients experience difficulties in recognizing a face (prosopagnosics), but they can still recognize its expression. The dissociation between these two face-related skills has served as a keystone of models of face processing. We now report that the presence of a facial expression can influence face identification. For normal viewers, the presence of a facial expression influences performance negatively, whereas for prosopagnosic patients, it improves performance dramatically. Accordingly, although prosopagnosic patients show a failure to process the facial configuration in the interest of face identification, that ability returns when the face shows an emotional expression. Accompanying brain-imaging results indicate activation in brain areas (amygdala, superior temporal sulcus, parietal cortex) outside the occipitotemporal areas normally activated for face identification and lesioned in these patients. This finding suggests a modulatory role of these areas in face identification that is independent of occipitotemporal face areas.

Transient postoperative prosopagnosia

A 23-year-old right-handed woman developed isolated transient prosopagnosia following surgical resection of a right posterior temporal seizure focus. At 18 years of age she had developed secondarily generalized tonic-clonic seizures. Preoperative neuropsychological evaluation was normal, and neurological examination revealed only a left superior quadrant achromatopsia. MRI revealed a circumscribed lesion in the right inferolateral temporo-occipital junction. Following surgery she was agitated for 36 hours, and afterward, when her attention and orientation improved, she was unable to recognize familiar faces. She could, however, recognize familiar voices. Her prosopagnosia resolved over the next 6-7 days. This case demonstrates that isolated prosopagnosia can occur in patients with lesions restricted to the right inferior posterior temporal-anterior occipital region. The temporary nature of the prosopagnosia may result from postsurgical tissue injury, including focal cerebral edema, with compensation by ipsilateral or contralateral areas.

Impaired configurational processing in a case of progressive prosopagnosia associated with predominant right temporal lobe atrophy

F.G., a 71-year-old right-handed man, presented with a slowly progressive deterioration in his ability to recognize faces of familiar and famous persons, contrasting with the relative preservation of other cognitive domains. His primary face perception skills were intact. Along with his face-recognition deficit, F.G. also exhibited a mild visual agnosia. A more detailed analysis of his performance on visuoperceptual tests revealed a selective deficit in retrieving the configurational representation of complex visual entities and an over-reliance on analysing individual features. Quantitative volumetric measurements of his temporal lobe structures showed a prevalent atrophy of the right fusiform gyrus and parahippocampal cortex. The results of the present study suggest that a right temporal variant of frontotemporal lobar degeneration may be characterized over a period of several years by an impaired configurational processing of visually complex entities in the absence of any semantic deficit.