Developmental prosopagnosia: a study of three patients

We studied perception in three patients with prosopagnosia of childhood onset. All had trouble with other 'within-category' judgments. All were deficient on face matching tests and severely impaired on tests of perception of the spatial relations of facial features and abstract designs, indicating a deficit in the encoding of coordinate relationships, similar to adult-onset prosopagnosia with lesions of the fusiform face area. Two had difficulty perceiving feature colour, which correlated with reduced luminance sensitivity. In contrast to adult-onset patients, saturation discrimination was spared in two and spatial resolution impaired in two. Curvature discrimination was relatively spared. Contrast sensitivity showed variable reductions at different spatial frequencies. We conclude that developmental prosopagnosia is similar to the adult-onset form in encoding deficits for the spatial arrangement of facial elements. Deficits in luminance perception and spatial resolution are more associated with defective encoding for basic object-level recognition, as shown on tests of object and spatial perception.     

Covert face recognition in prosopagnosia: A review

Prosopagnosia, a spectacular face agnosia, is generally detected and discussed on the basis of explicit or overt performance of the subjects. However, recent observations suggest that an overt response is probably not sufficient to determine what is and what is not preserved in the cognitive processing of faces by prosopagnosia. Indeed, signs of covert knowledge have been evidenced in some, but not all, subjects, indicating that they are still able to use representations they cannot use overtly. Empirical data, showing that the nature of prosopagnosia is a more complex phenomenon than has been thought and that the processing models should be adjusted accordingly, are reviewed.     

Childhood prosopagnosia

K.D. has been unable to recognize people's faces since sustaining cerebral injury in infancy. Investigation of this disorder carried out when K.D. was aged 8 to 11 years showed that although her basic visual abilities were impaired, they were no poorer than those of other children who recognized faces without difficulty. K.D. had learned to read, but had not regained ability to recognize people's faces; instead she relied primarily on voices as a cue to person recognition. There was no evidence of any degree of overt or covert recognition of familiar faces, and K.D. also experienced problems in visual object recognition. She could, however, classify a visual input as a face, was able to perceive and imitate facial expressions, and was able to perform face matching tasks to an extent limited by her use of a feature by feature matching strategy. It is suggested that K.D.'s impairment affected higher order perceptual abilities, and is in a number of respects comparable to the impairments found in adult prosopagnosic patients.     

Congenital prosopagnosia: face-blind from birth

Congenital prosopagnosia refers to the deficit in face processing that is apparent from early childhood in the absence of any underlying neurological basis and in the presence of intact sensory and intellectual function. Several such cases have been described recently and elucidating the mechanisms giving rise to this impairment should aid our understanding of the psychological and neural mechanisms mediating face processing. Fundamental questions include: What is the nature and extent of the face-processing deficit in congenital prosopagnosia? Is the deficit related to a more general perceptual deficit such as the failure to process configural information? Are any neural alterations detectable using fMRI, ERP or structural analyses of the anatomy of the ventral visual cortex? We discuss these issues in relation to the existing literature and suggest directions for future research.     

Developmental coordination disorder: a review of research on subtypes and comorbidities

The interest in Developmental Coordination Disorder (DCD) has grown considerably over the last decade. Nevertheless, its etiology and prognosis are still poorly understood. The idea is growing that DCD may not be a uniform disorder. This review summarizes research on DCD, with a particular focus on subtype and comorbidity studies. The main message of the paper is that, in order to understand the etiology and prognosis of DCD, we need to have a better understanding of its nature. This requires an awareness of the existence of subtypes and comorbidities. Current theories on comorbidity phenomena are discussed in terms of their possible merit for the development of the field. Particular attention is given to the Automatization Deficit Hypothesis, a theory based on research on dyslexia.     

Developmental reversals in false memory: a review of data and theory

Can susceptibility to false memory and suggestion increase dramatically with age? The authors review the theoretical and empirical literatures on this counterintuitive possibility. Until recently, the well-documented pattern was that susceptibility to memory distortion had been found to decline between early childhood and young adulthood. That pattern is the centerpiece of much expert testimony in legal cases involving child witnesses and victims. During the past 5 years, however, several experiments have been published that test fuzzy-trace theory's prediction that some of the most powerful forms of false memory in adults will be greatly attenuated in children. Those experiments show that in some common domains of experience, in which false memories are rooted in meaning connections among events, age increases in false memory are the rule and are sometimes accompanied by net declines in the accuracy of memory. As these experiments are strongly theory-driven, they have established that developmental improvements in the formation of meaning connections are necessary and sufficient to produce age increases in false memory.     

Visual agnosia and prosopagnosia in childhood: a prospective case study.

Selective impairments in visual processing are well documented in adults but rarely reported in children. The few childhood cases reported are mostly retrospective accounts with little attention paid to developmental, assessment or management issues. We report a prospective case study of a boy with prosopagnosia and visual processing deficits of presumed developmental origin. At the age of 4 years, AL presented with a range of cognitive and visual recognition deficits. Subsequent assessments revealed an evolving pattern in visual recognition and dissociations between developing skills. At the age of 7 AL has impairments in early perceptual analysis, visual organisation and in complex visual processing. Although he can identify facial features and match faces he is unable to recognise familiar faces. His reading and spelling are developing normally. The nature of his deficits and his progress are discussed within a cognitive neuropsychological framework.     

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.     

Gaze behaviour in hereditary prosopagnosia

Prosopagnosia is the inability to recognize someone by the face alone in the absence of sensory or intellectual impairment. In contrast to the acquired form of prosopagnosia we studied the congenital form. Since we could recently show that this form is inherited as a simple monogenic trait we called it hereditary form. To determine whether not only face recognition and neuronal processing but also the perceptual acquisition of facial information is specific to prosopagnosia, we studied the gaze behaviour of four hereditary prosopagnosics in comparison to matched control subjects. This rarely studied form of prosopagnosia ensures that deficits are limited to face recognition. Whereas the control participants focused their gaze on the central facial features, the hereditary prosopagnosics showed a significantly different gaze behaviour. They had a more dispersed gaze and also fixated external facial features. Thus, the face recognition impairment of the hereditary prosopagnosics is reflected in their gaze behaviour.     

Understanding provoked overt recognition in prosopagnosia

Prosopagnosic patients are unable to recognize overtly the faces of familiar people. However, under specific experimental conditions, overt recognition of faces has been induced in some prosopagnosics. This phenomenon of provoked overt recognition has proved challenging for current theories of face recognition. We first describe clinical demonstrations of provoked overt recognition, before highlighting some critical features that any satisfactory explanation of the phenomenon must accommodate. An account of provoked overt recognition is then put forward, couched within the framework of Burton, Bruce, and Johnston's (1990) IAC model of face recognition. This theory is tested by running computer simulations with the model. Finally, the present explanation of provoked overt recognition is scrutinized to discover whether it has implications for rehabilitation work with prosopagnosic patients.     

Implicit familiarity processing in congenital prosopagnosia

A particularly interesting and somewhat puzzling finding in the face‐processing literature is that, despite the absence of overt recognition of most faces, many patients with acquired prosopagnosia (AP) exhibit evidence of intact covert face recognition of the very same faces. This phenomenon has important implications for the understanding of the mechanism underlying AP and, by extension, the mechanism underlying normal face processing. Here, we set out to examine whether individuals with congenital prosopagnosia (CP) exhibit a similar dissociation between overt and covert face recognition. We first confirmed that all six of our CP individuals were significantly impaired in face recognition in comparison with controls. Participants then completed a matching task with both famous and unknown faces in which they decided whether two consecutive images have the same identity or not. Critically, the level of face familiarity was orthogonal to the task at hand and this enabled us to examine whether the familiarity of a face enhanced identity matching, a finding which would implicate implicit face processing. As expected, the CP individuals were slower and less accurate than the control participants. More importantly, like the controls, the CP individuals were faster and more accurate at matching famous compared with unknown faces. Also, for both groups, matching performance on unrecognized famous faces fell at an intermediate level between performance on explicitly recognized famous faces and faces which are unknown. These results provide the first solid evidence for the existence of implicit familiarity processing in CP and suggest that, despite the marked impairment in explicit face recognition, these individuals still have some familiarity representation which manifests in the form of covert recognition. We discuss possible models to account for the apparent dissociation of overt and covert face processing in CP.     

Developmental stages,Piagetian stages in particular: A critical review

Developmental stages in general and Piaget's stages in particular have given rise to considerable controversy. Much of this controversy revolves around the responses that have been given to the following five central questions: (1) Do developmental stages exist? (2) If they exist, where are they? (3) What features define a developmental sequence as a sequence of developmental stages? (4) What psychological processes underlie developmental change? (5) Should we abandon the concept of developmental stages? The main goal of this paper is to present a critical review of such responses, while arguing for a strong conception of development and a “non-received” view of Piaget's theory. After an introduction section, we elaborate on each of the five questions. Finally, we present several reasons why this paper often appeals to Piaget's theory, and why his theory has been greatly misunderstood.     

Developmental considerations for assessment of trauma symptoms in preschoolers: a review of measures and diagnoses

Child maltreatment can lead to a unique set of trauma stress among young children that can be challenging to measure. The purpose of this review was to review measures of maltreatment-related trauma outcomes (trauma-related symptoms and post-traumatic stress disorders) in very young children (ages 0–6) and to examine research trends in how and if child development is accounted for in this area of measurement. A systematic search strategy was used to identify articles in two databases, CINAHL and PsychInfo. Articles were eligible for inclusion in the review if they measured trauma symptoms in children ages 0–6, were quantitative research reports of studies conducted in North America, and were published in English. The search resulted in 74 articles meeting prespecified inclusion criteria. Results suggested that recognition of the ways maltreatment trauma affects child development and the importance of developmental sensitivity in assessing trauma symptoms has grown in recent years. However, many research studies did not use developmental frameworks and applied adult-oriented trauma symptom frameworks in measurement and treatment. Behavioral symptoms were the primary outcome of interest for this age group. There was also incongruity and lack of consensus about diagnostic tools for post-traumatic stress disorders in young children. Further research is needed to resolve theoretical and empirical controversies related to measurement and diagnosis of trauma symptomatology in young children.     

Cognitive heterogeneity in genetically based prosopagnosia: A family study

Congenital prosopagnosia (CP) is a selective difficulty in recognizing familiar faces that is present from birth. There is mounting evidence for a familial factor in CP, possibly due to a simple autosomal inheritance pattern. However, potential candidate genes remain to be established, and the question whether genetically based CP is a single trait, or a cluster of related subtypes differing in the pattern of impairments to specific components of the face‐processing system, remains unanswered. In addition, since the great majority of so far described cases with CP were adult at the time of investigation, it remains unknown which specific aspects of face processing are impaired in small children with CP. Here we present the first study that specifically addresses these questions by elucidating the specific mechanisms underlying face‐recognition impairments in seven individuals with CP (aged 4–87 years) belonging to four generations of the same family. Our results indicate that genetically based CP is not a single trait but a cluster of related subtypes, since the pattern of impairments to specific components of the face‐processing system varies in individuals belonging to the same family. In addition, we show that the heterogeneity of the cognitive profile in CP with respect to specific aspects of face processing is apparent from early childhood.     

Further observations on the nature of prosopagnosia

Two new cases of prosopagnosia are described and compared with pertinent clinical material from the English language literature. The interpretation of this disorder most compatible with the clinical data appears to us to be that there is an underspecification of visuoperceptive information preventing both the formation of significant face images and the retrieval of well-known face memoranda existing within a relatively intact visual remote memory store. Failure of formation of immediate memoranda of similarly complex visual images is also commonly observed but does not seem to be a requirement for the symptom of prosopagnosia. Conceptualizing this abnormality as simply a material specific visual agnosia of images beyond the classifier level would still appear to be acceptable if less informative.     

Symptoms of prosopagnosia in intoxicated subjects.

Two experiments were made to test whether a blood ethanol concentration of about 1 g ethanol per kg blood influences the ability to recognize faces which were shown 24 hours earlier. 18 subjects who saw the faces for the first time when sober and whose task it was to recognize the faces when under the influence of alcohol, recognized the faces significantly less frequently than controls. The controls saw the faces for the first time when sober and their task was to recognize the faces later when also in a sober state. When 20 sober subjects had to recognize faces which they had seen 24 hours earlier under the influence of alcohol, they recognized the faces significantly less frequently than controls. 18 subjects to whom visual forms were shown when under the influence of alcohol and who had to recognize these forms 24 hours later when sober again performed like subjects who had to recognize faces under identical experimental conditions. Subjects who saw the forms, however, in a sober state and who had to recognize these forms when intoxicated performed significantly better than subjects who had to recognize faces under identical experimental conditions. In additional experiments, it was shown that alcohol did not influence ability to compare simultaneously presented faces. Intoxicated subjects' reduced abilities to recognize faces is regarded as a symptom of prosopagnosia since it cannot be explained by a reduced ability to recognize forms or to compare faces.     

Structure and function in acquired prosopagnosia: Lessons from a series of 10 patients with brain damage

Acquired prosopagnosia varies in both behavioural manifestations and the location and extent of underlying lesions. We studied 10 patients with adult‐onset lesions on a battery of face‐processing tests. Using signal detection methods, we found that discriminative power for the familiarity of famous faces was most reduced by bilateral occipitotemporal lesions that involved the fusiform gyri, and better preserved with unilateral right‐sided lesions. Tests of perception of facial structural configuration showed severe deficits with lesions that included the right fusiform gyrus, whether unilateral or bilateral. This deficit was most consistent for eye configuration, with some patients performing normally for mouth configuration. Patients with anterior temporal lesions had better configuration perception, though at least one patient showed a more subtle failure to integrate configural data from different facial regions. Facial imagery, an index of facial memories, was severely impaired by bilateral lesions that included the right anterior temporal lobe and marginally impaired by fusiform lesions alone; unilateral right fusiform lesions tended to spare imagery for facial features. These findings suggest that (1) prosopagnosia is more severe with bilateral than unilateral lesions, indicating a minor contribution of the left hemisphere to face recognition, (2) perception of facial configuration critically involves the right fusiform gyrus and (3) access to facial memories is most disrupted by bilateral lesions that also include the right anterior temporal lobe. This supports assertions that more apperceptive variants of prosopagnosia are linked to fusiform damage, whereas more associative variants are linked to anterior temporal damage. Next, we found that behavioural indices of covert recognition correlated with measures of overt familiarity, consistent with theories that covert behaviour emerges from the output of damaged neural networks, rather than alternative pathways. Finally, to probe the face specificity of the prosopagnosic defect, we tested recognition of fruits and vegetables: While face specificity was not found in most of our patients, the data of one patient suggested that this may be possible with more focal lesions of the right fusiform gyrus.     

Voice recognition and the posterior cingulate: An fMRI study of prosopagnosia

Voices, in addition to faces, enable person identification. Voice recognition has been shown to evoke a distributed network of brain regions that includes, in addition to the superior temporal sulcus (STS), the anterior temporal pole, fusiform face area (FFA), and posterior cingulate gyrus (pCG). Here we report an individual (MS) with acquired prosopagnosia who, despite bilateral damage to much of this network, demonstrates the ability to distinguish voices of several well‐known acquaintances from voices of people that he has never heard before. Functional magnetic resonance imaging (fMRI) revealed that, relative to speech‐modulated noise, voices rated as familiar and unfamiliar by MS elicited enhanced haemodynamic activity in the left angular gyrus, left posterior STS, and posterior midline brain regions, including the retrosplenial cortex and the dorsal pCG. More interestingly, relative to noise and unfamiliar voices, the familiar voices elicited greater haemodynamic activity in the left angular gyrus and medial parietal regions including the dorsal pCG and precuneus. The findings are consistent with theories implicating the pCG in recognizing people who are personally familiar, and furthermore suggest that the pCG region of the voice identification network is able to make functional contributions to voice recognition even though other areas of the network, namely the anterior temporal poles, FFA, and the right parietal lobe, may be compromised.