This article reviews recent research findings investigating developmental prosopagnosia. Studies involving DP address the cognitive and neural basis of face processing. The relatively rich cognitive, neural, and developmental theories of face recognition provide a framework that should allow for rapid progress. Cognitive studies of DP provide support for the existence of face-specific processes, and dissociations between different types of face processing in DPs are consistent with leading models of face processing that propose separable mechanisms for various aspects of face processing. (...) Research on the neural basis of DP has found abnormalities in a number of occipital and temporal regions that show face-selective responses in people with normal face processing, and so provide additional evidence that the integrity of these areas is necessary for face recognition. Despite progress made in recent years, much work remains to be done and connections between cognitive, neural, developmental, and genetic levels of explanation remain to be worked out. (shrink)

Some cases of prosopagnosia involve a highly circumscribed loss of A-consciousness. When seen in this way they offer further support for the arguments made in Block's target article.

Face recognition depends upon the uniqueness of each human face. This is accomplished by the patterns formed by the unique relationship among face features. Unique face-patterns are produced by the intrusion of random factors into the process of biological growth and development. Processes are described which enable a unique face-pattern to be represented as a percept in the visual sensory system. The components of the face recognition system are analyzed as is the manner in which the precept is connected through (...) microcircuits to a memory file so that the history of a perceiver’s encounters with a familiar face enables the perceiver to access a memory store that is a record of the outcome of past encounters with the perceived. The importance of the face recognition system in enabling humans to individuate members the social group is discussed, as well as the importance of face recognition in the development of the individual’s social identity and ability to be a collaborative member of the social groups to which it belongs. The role of prosopagnosia—the inability to recognize familiar faces—in furthering an understanding of the face recognition system is examined, as is its importance in demonstrating the crucial nature of face recognition in human social functions. It is proposed that human face recognition is not a unique phenomenon but is an elaboration of processes existing in nonhuman primates as well as in lower animals. (shrink)

The enactive approach to perception describes experience as a temporally extended activity of skillful engagement with the environment. This paper pursues this view and focuses on prosopagnosia both for the light that the theory can throw on the phenomenon, and for the critical light the phenomenon can throw on the theory. I argue that the enactive theory is insufficient to characterize the unique nature of experience specific to prosopagnosic subjects. There is a distinct difference in the overall process of detection (...) (with respect to eye movement sequence) of familiar and unfamiliar faces in prosopagnosia; in contrast, normal subjects use the same scanning strategy when exploring both kinds of faces despite an obvious difference in qualitative character. In light of this limitation I outline a supplemental view basing sensorimotor contingencies upon the establishment and reaffirmation of regularities within the organism as it engages with the environment. (shrink)

We routinely need to process the identity of many faces around us, and how the brain achieves this is still the subject of much research in cognitive neuroscience. To date, insights on face identity processing have come from both healthy and clinical populations. However, in order to directly compare results across and within participant groups, and across different studies, it is crucial that a standard task is utilised which includes different exemplars (for example, non-face stimuli along with faces), is memory-neutral, (...) and taps into identity recognition across orientation and across viewpoint change. The goal of this study was to test a previously behaviourally tested, optimised face and object identity matching design in a healthy control sample whilst being scanned using fMRI. Specifically, we investigated categorical, orientation, and category-specific orientation effects while participants were focused on identity processing of simultaneously presented exemplar stimuli. Alongside observing category and orientation specific effects in a distributed set of brain regions, we also saw an interaction between stimulus category and orientation in the bilateral fusiform gyrus and bilateral middle occipital gyrus. Generally these clusters showed the pattern of a heightened response to inverted, as opposed to upright faces; and to upright, as opposed to inverted shoes. These results are discussed in relation to previous studies and to potential future research within prosopagnosic individuals. (shrink)

develops themes from the dissertation. I argue that two models of prosopagnosia are best understood as idealizing models, and as such are subject to importantly different methodological constraints from non-idealized theories of face recognition.

One of the traditional views of self-deception has been in terms of a dynamically-driven defense mechanism which is employed in order to enhance self-esteem by denying contradictory evidence. Denial is evident during stressful events in everyday life, as well as in cases of mental and somatic impairments. A detailed analysis of a specific neurological syndrome, prosopagnosia, where covert recognition of familiar faces may coexist with lack of overt recognition, demonstrates the inapplicability of the dynamic interpretation of self-deception in terms of (...) denial to some neurological syndromes, and the usefulness of a new conceptualization of this process in terms of dissociation between modular and central processes. It is proposed that self-deception be considered a complex process which may be conceived of as a defense mechanism in everyday life, and as a product of functional dissociation in neurological syndromes. (shrink)

Face recognition is impaired in patients with prosopagnosia, which may occur as a side effect of neurosurgical procedures. Face selective regions on the ventral temporal cortex have been localized with electrical cortical stimulation, electrocorticography, and functional magnetic resonance imagining. This is the first group study using within-patient comparisons to validate face selective regions mapping, utilizing the aforementioned modalities. Five patients underwent surgical treatment of intractable epilepsy and joined the study. Subdural grid electrodes were implanted on their ventral temporal cortices to (...) localize seizure foci and face selective regions as part of the functional mapping protocol. Face selective regions were identified in all patients with fMRI, four patients with ECoG, and two patients with ECS. From 177 tested electrode locations in the region of interest, which is defined by the fusiform gyrus and the inferior temporal gyrus, 54 face locations were identified by at least one modality in all patients. fMRI mapping showed the highest detection rate, revealing 70.4% for face selective locations, whereas ECoG and ECS identified 64.8 and 31.5%, respectively. Thus, 28 face locations were co-localized by at least two modalities, with detection rates of 89.3% for fMRI, 85.7% for ECoG and 53.6 % for ECS. All five patients had no face recognition deficits after surgery, even though five of the face selective locations, one obtained by ECoG and the other four by fMRI, were within 10 mm to the resected volumes. Moreover, fMRI included a quite large volume artifact on the ventral temporal cortex in the ROI from the anatomical structures of the temporal base. In conclusion, ECS was not sensitive in several patients, whereas ECoG and fMRI even showed activation within 10 mm to the resected volumes. Considering the potential signal drop-out in fMRI makes ECoG the most reliable tool to identify face selective locations in this study. A multimodal approach can improve the specificity of ECoG and fMRI, while simultaneously minimizing the number of required ECS sessions. Hence, all modalities should be considered in a clinical mapping protocol entailing combined results of co-localized face selective locations. (shrink)

Explanations of Capgras delusion and prosopagnosia typically incorporate a dual-route approach to facial recognition in which a deficit in overt or covert processing in one condition is mirror-reversed in the other. Despite this double dissociation, experiences of either patient-group are often reported in the same way – as lacking a sense of familiarity toward familiar faces. In this paper, deficits in the facial processing of these patients are compared to other facial recognition pathologies, and their experiential characteristics mapped onto the (...) dual-route model in order to provide a less ambiguous link between facial processing and experiential content. The paper concludes that the experiential states of Capgras delusion, prosopagnosia, and related facial pathologies are quite distinct, and that this descriptive distinctiveness finds explanatory equivalence at the level of anatomical and functional disruption within the face recognition system. The role of skin conductance response as a measure of ‘familiarity’ is also clarified. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Philosophy, Psychiatry, & Psychology 9.1 (2002) 65-72 [Access article in PDF] Multiple Paths to Delusion Philip Gerrans Response to Phillips JAMES PHILLIPS COMMENTS are summarized in four recommendations. Clarify the Relationship of the Cognitive Model to its Neuroscientific Base The cognitive approach postulates a cognitive entity whose information-processing properties explain a symptom or unify a set of symptoms. The key idea is that we can use a model of (...) normal cognitive functioning to explain a disorder in terms of failure of a component of the model. In the case under discussion, the symptom is the loss of affect, which is part of the clinical profile of both the Capgras and Cotard delusions. The body of neuropsychological data concerning links between recognitional and affective processes extends back at least to Charcot's patient M. X. whose affective responses to familiar situations were lost, together with his visual episodic memory. M. X described his phenomenology this way: A remarkable consequence of this loss of mental ability is, as I have said, the change in my personality and impressions. I am much less affected by sorrow or grief. I can tell you that, after losing one of my relatives with whom I was very close, I experienced a much less intense grief than if I had still been able to image the features of that relative, the stages of the illness he went through, or especially if I had been able to picture to myself [voir interieurement] the outward effect of this untimely death on the members of my family. (Young and van de Wal 1996) (It is interesting to note that M. X. retained insight into his condition and explained it in a lucid, rational way rather than forming a delusional belief. Initial evidence for a two-stage theory, one might have thought).Given convergent evidence that the limbic system is the basis of affective states, the hypothesis that the delusions under discussion are rationalizations of unusual affective experiences consequent on abnormal limbic function or loss of connection between limbic and other functions is an inference to the best explanation. The Young-Ellis model is a cognitive model that describes cognitive function at what Dennett calls the design level, intermediate between what Marr called the computational level and level of representation and algorithm. As such it implies only that the boxes and arrows are implemented neurally, but endorses no hypotheses about the nature of that implementation.It is correct of Phillips to observe that the crucial inference about the link between affective and cognitive function is grounded in a background theory of the relationship between cognitive models, clinical symptoms, and neurobiology. If Phillips' complaint is that the model cannot be sheeted home to a neurobiological substrate, [End Page 65] this is true. Implementation theories are thin on the ground in cognitive science because they would require a theory of biological computation that, despite partisan claims, is elusive. Nonetheless, information-processing models and partial implementation theories for specific functions such as perception, language, face recognition, and the affective systems do exist. The allusion to cognitive structure remains sound as long as it accounts for observable clinical and experimental data and makes verifiable predictions.The fact that the Young-Ellis model of face recognition can account for both normal function and a variety of forms of prosopagnosia together (under assumptions about the relation between belief and experience) with delusions of misidentification counts in its favor (Ellis 1998).Phillips objection to cognitive theories is stronger when we turn to models of belief and rationality. In the case of functions such as face recognition or language, there is a variety of convergent evidence, especially from deficit studies, to support a model of normal cognitive function. For example, we know that face recognition activates schemas concerning orientation, features, emotions, and gender because these components can be selectively damaged (Young 1998). However, we lack a model of normal human reasoning other than "folk theory" of belief-desire psychology. Cognitive theories of belief formation are often forced to use models derived from philosophy such as logic, probability theory, or decision theory, which are amenable to... (shrink)

A key element of the distinction between explicit and implicit cognitive functioning is the presence or absence of conscious awareness. In this review, we consider the proposal that neuropsychological disorders can best be considered in terms of a decoupling between preserved implicit or unconscious processing and impaired explicit or conscious processing. Evidence for dissociations between implicit and explicit processes in blindsight, amnesia, object agnosia, prosopagnosia, hemi-neglect, and aphasia is examined. The implications of these findings for a) our understanding of a (...) variety of neuropsychological disorders, b) the conceptualization of normal cognitive functioning, c) the neural basis of consciousness, and d) the clinical rehabilitation of brain-injured individuals are also discussed. (shrink)

This study probes whether a prosopagnosic patient can make accurate explicit affective judgements towards faces. Patient MJH was shown photographs of faces of well-liked family members and public figures rated as “evil” by opinion polls. MJH was asked to rate each face on two 7-point scales (Likeability and Pleasantness). Since he is unable to explicitly recognise faces, his ratings were based on his evaluative reaction to the faces presented. In a second phase of the experiment, MJH was told the name (...) of the faces previously presented and asked to rate them using the same scales. MJH's Likeability ratings during the picture-viewing phase of the experiment and the explicit phase were highly correlated. Based on these findings, we propose that thought consists of an explicit declarative and an implicit emotional aspect, which may become dissociated in prosopagnosia. (shrink)

Anecdotal reports obtained from three individuals with prosopagnosia, all of whom have participated in an investigation, capture the essence of their impairment. This article focuses on the contrast between two prominent forms of prosopagnosia, one of which results from an acquired brain insult in an otherwise premorbidly normal individual and a second which appears to be lifelong and occurs in the absence of any obvious brain damage, at least as evident on conventional brain imaging. It reviews two central issues: the (...) first concerns the similarities and differences in the psychological representations of faces in acquired prosopagnosia and congenital prosopagnosia, and the second concerns the nature of the underlying neural representations of faces in these two populations. Some well-established overlapping behavioral characteristics are identified. (shrink)

The chapters published in this volume developed from presentations, and their associated discussions at a conference organised by the Scottish Branch of the British Psychological Society, held at Rothesay, Isle of Bute, Scotland in September 1987. The goal of the conference was to bring together workers across a wide area of neuropsychological research to discuss recent technological advances, developments in assessment and rehabilitation, and to address theoretical issues of current interest. Thus, the chapters in this book include contributions on the (...) use of Magnetic Resonance Imaging and Single Photon Emission Computed Tomography in neuropsychological research, studies of hemi spheric specialisation and cooperation, alcoholic and Alzheimer type dementia, prosopagnosia and facial processing, the assessment, management and rehabilitation of memory problems, the assessment of premorbid intellectual status and issues in developmental neuropsychology. Many of those engaged in research and clinical practice in neuropsychology encounter a range of topic at least as wide as this in their professional lives. The opportunity for researchers and clinicians to discuss some of the key issues in the field was invaluable and we hope that readers gain as much from the material presented here as the participants did from the meeting itself. (shrink)