Developmental prosopagnosia in childhood

Familial Transmission of Developmental Prosopagnosia: New Case Reports from an Extended Family and Identical Twins

Existing evidence suggests that developmental prosopagnosia (DP) is a surprisingly prevalent condition, with some individuals describing lifelong difficulties with facial identity recognition. Together with case reports of multiple family members with the condition, this evidence suggests that DP is inherited in at least some instances. Here, we offer some novel case series that further support the heritability of the condition. First, we describe five adult siblings who presented to our lab with symptoms of DP. Second, for the first known time in the literature, we describe a pair of adult identical twins who contacted us in the belief that they both experience DP. The condition was confirmed in three of the five siblings (with minor symptoms observed in the remaining two) and in both twins. Supplementary assessments suggested that all individuals also experienced some degree of difficulty with facial identity perception, but that object recognition was preserved. These findings bolster the evidence supporting the heritability of DP and suggest that it can be a specific impairment in some cases.

"Calculating faces": can face perception paradigms enrich dyscalculia research?

Developmental dyscalculia (DD) is a subtype of learning disabilities, which is characterized by lower mathematical skills despite average intelligence and average or satisfactory performance in other academic areas. It is not fully understood how such deficits emerge in the course of brain development. When considering the mechanisms of dyscalculia, two domain-specific systems are distinguished. The Approximate Number System (ANS) is related to the approximate estimation of large sets, and the Object Tracking System (OTS) is responsible for subitizing, that is, the exact quantification of small sets. In recent years, the multiple-deficit framework has become increasingly popular. On the one hand, it explains the impairment of certain general cognitive functions in children with DD, such as executive functions, attention, visual-perceptual discrimination, processing speed, and rapid scanning of visual information. On the other hand, it provides a theoretical basis for explaining the simultaneous occurrence of the different types of other comorbid conditions (such as dyslexia and ADHD) and the relationship between them. We suggest that the face recognition could be considered as another, probably impaired function in dyscalculic individuals. We highlight several brain areas involved both in numerical and facial processing: intraparietal sulcus (IPS), fusiform gyrus (FFG), and hippocampus (HC). We consider the possibility of expanding the scope of dyscalculia research by application of face perception paradigms.

Individuals with developmental prosopagnosia show independent impairments in face perception, face memory and face matching

Individuals with developmental prosopagnosia (DP) all exhibit impairments in face memory, but the specificity of these face memory impairments is debated. One problem is that standard behavioural tasks are not able to provide independent measurement of face perception, face memory, and face matching (the decision process required to judge whether two instances of a face are of the same individual or different individuals). The present study utilised a new test of face matching, the Oxford Face Matching Test (OFMT), and a novel analysis strategy to derive these independent indices. Twenty-nine individuals with DP and the same number of matched neurotypical controls completed the OFMT, the Glasgow Face Matching Test, and the Cambridge Face Memory Test. Results revealed individuals with DP exhibit impairments in face perception, face memory and face matching. Collectively, these results suggest that face processing impairments in DP are more comprehensive than has previously been suggested.

OUP accepted manuscript

While there have been decades of clinical and theoretical interest in developmental and acquired face recognition difficulties, very little work has examined their remediation. Here, we report two studies that examined the efficacy of an existing face training programme in improving face-processing skills in adults and children with developmental face recognition impairments. The programme has only been trialled in typical children to date, where 2 weeks of perceptual training (modelled on an adapted version of the popular family game Guess Who?) resulted in face-specific improvements for memory but not perception after 2 weeks of training. In Study 1, we performed a randomized, parallel groups, placebo-controlled trial of the same programme in 20 adults with a pre-existing diagnosis of developmental prosopagnosia. Assessment tasks were administered immediately before and after training, and 2 weeks later. Face-specific gains in memory (but not perception) were observed in the experimental group and were greatest in those with the poorest face recognition skills at entry. These gains persisted 2 weeks after training ceased. In Study 2, a case-series approach was used to administer the experimental version of the training programme to four children who presented with difficulties in face recognition. Improvements in face memory were observed in three of the participants; while one also improved at face perception, there was mixed evidence for the face specificity of these gains. Together, these findings suggest plasticity in the human face recognition system through to at least mid-adulthood and also pave the way for longer-term implementations of the face training programme that will likely elicit greater gains in both adults and children.

Visual development

The developing visual brain is an integrated system, linking analysis of the visual input to visuomotor control, visual cognition, and attention. Major points in human visual development are the presence of rudimentary pathways present at birth which can control fixation behavior, with subsequent development of specific functions. These functions include the emergence of cortical selectivity; the integration of local signals to provide global representations of motion, shape, and space; the development of visuomotor modules for eye movements, manual reaching, and locomotion; and the development of distinct attentional systems. Measures of these processes in infancy and early childhood can provide indicators of broader brain development in the at-risk child. A key system in development is the dorsal cortical stream. Measures of global motion processing, visuomotor actions, and attention suggest that this system is particularly vulnerable in children with a wide range of neurodevelopmental disorders. Early disorders of the eye (strabismus, cataract) reveal the level of plasticity in the developing visual system and the ways in which early experience can affect the course of functional development.

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.

Individual differences in the detection, matching and memory of faces

Previous research has explored relationships between individual performance in the detection, matching and memory of faces, but under limiting conditions. The current study sought to extend previous findings with a different measure of face detection, and a more challenging face matching task, in combination with an established test of face memory. Experiment 1 tested face detection ability under conditions designed to maximise individual differences in accuracy but did not find evidence for relationships between measures. In addition, in Experiments 2 and 3, which utilised response times as the primary performance measure for face detection, but accuracy for face matching and face memory, no correlations were observed between performance on face detection and the other tasks. However, there was a correlation between accuracy in face matching and face memory, consistent with other research. Together, these experiments provide further evidence for a dissociation between face detection, and face matching and face memory, but suggest that these latter tasks share some common mechanisms.

Developmental prosopagnosics have widespread selectivity reductions across category-selective visual cortex

Developmental prosopagnosia (DP) is a neurodevelopmental disorder characterized by severe deficits with facial identity recognition. It is unclear which cortical areas contribute to face processing deficits in DP, and no previous studies have investigated whether other category-selective areas function normally in DP. To address these issues, we scanned 22 DPs and 27 controls using a dynamic localizer consisting of video clips of faces, scenes, bodies, objects, and scrambled objects. We then analyzed category selectivity, a measure of the tuning of a cortical area to a particular visual category. DPs exhibited reduced face selectivity in all 12 face areas, and the reductions were significant in three posterior and two anterior areas. DPs and controls showed similar responses to faces in other category-selective areas, which suggests the DPs' behavioral deficits with faces result from problems restricted to the face network. DPs also had pronounced scene-selectivity reductions in four of six scene-selective areas and marginal body-selectivity reductions in two of four body-selective areas. Our results demonstrate that DPs have widespread deficits throughout the face network, and they are inconsistent with a leading account of DP which proposes that posterior face-selective areas are normal in DP. The selectivity reductions in other category-selective areas indicate many DPs have deficits spread across high-level visual cortex.

Identifying Hallmark Symptoms of Developmental Prosopagnosia for Non-Experts

Developmental prosopagnosia (DP) is characterised by a severe and relatively selective deficit in face recognition, in the absence of neurological injury. Because public and professional awareness of DP is low, many adults and children are not identified for formal testing. This may partly result from the lack of appropriate screening tools that can be used by non-experts in either professional or personal settings. To address this issue, the current study sought to (a) explore when DP can first be detected in oneself and another, and (b) identify a list of the condition’s everyday behavioural manifestations. Questionnaires and interviews were administered to large samples of adult DPs, their unaffected significant others, and parents of children with the condition; and data were analysed using inductive content analysis. It was found that DPs have limited insight into their difficulties, with most only achieving realisation in adulthood. Nevertheless, the DPs’ reflections on their childhood experiences, together with the parental responses, revealed specific indicators that can potentially be used to spot the condition in early childhood. These everyday hallmark symptoms may aid the detection of individuals who would benefit from objective testing, in oneself (in adults) or another person (for both adults and children).

Super-recognition in development: A case study of an adolescent with extraordinary face recognition skills

Face recognition abilities vary widely. While face recognition deficits have been reported in children, it is unclear whether superior face recognition skills can be encountered during development. This paper presents O.B., a 14-year-old female with extraordinary face recognition skills: a "super-recognizer" (SR). O.B. demonstrated exceptional face-processing skills across multiple tasks, with a level of performance that is comparable to adult SRs. Her superior abilities appear to be specific to face identity: She showed an exaggerated face inversion effect and her superior abilities did not extend to object processing or non-identity aspects of face recognition. Finally, an eye-movement task demonstrated that O.B. spent more time than controls examining the nose - a pattern previously reported in adult SRs. O.B. is therefore particularly skilled at extracting and using identity-specific facial cues, indicating that face and object recognition are dissociable during development, and that super recognition can be detected in adolescence.

Individual Differences in Face Recognition: A Decade of Discovery

Given the vital role face recognition plays in human social interaction, variations in this ability hold inherent interest and potential consequence. Yet the science of such differences has long lagged behind that of differences in other cognitive domains. In particular, although scattered case reports of catastrophic face-recognition deficits due to brain damage date back more than a century, for many decades, virtually no attention was paid to naturally occurring individual differences in face recognition. This past decade, in contrast, has seen a remarkable acceleration of research into these naturally occurring differences, spurred by the creation and validation of high-quality measures, open sharing of these measures, new options for remote testing, and a concerted move toward larger and more multivariate investigations. In this article, I recount six fundamental insights gained during the past decade about individual differences in face recognition—concerning their broad range, cognitive specificity, strong heritability, resilience to change, life-span trajectory, and practical relevance. Insights like these support a richer understanding of individual social experience and could enable more informed individual and institutional decision making.

Developmental visual perception deficits with no indications of prosopagnosia in a child with abnormal eye movements

Visual categories are associated with eccentricity biases in high-order visual cortex: Faces and reading with foveally-biased regions, while common objects and space with mid- and peripherally-biased regions. As face perception and reading are among the most challenging human visual skills, and are often regarded as the peak achievements of a distributed neural network supporting common objects perception, it is unclear why objects, which also rely on foveal vision to be processed, are associated with mid-peripheral rather than with a foveal bias. Here, we studied BN, a 9 y.o. boy who has normal basic-level vision, abnormal (limited) oculomotor pursuit and saccades, and shows developmental object and contour integration deficits but with no indication of prosopagnosia. Although we cannot infer causation from the data presented here, we suggest that normal pursuit and saccades could be critical for the development of contour integration and object perception. While faces and perhaps reading, when fixated upon, take up a small portion of central visual field and require only small eye movements to be properly processed, common objects typically prevail in mid-peripheral visual field and rely on longer-distance voluntary eye movements as saccades to be brought to fixation. While retinal information feeds into early visual cortex in an eccentricity orderly manner, we hypothesize that propagation of non-foveal information to mid and high-order visual cortex critically relies on circuitry involving eye movements. Limited or atypical eye movements, as in the case of BN, may hinder normal information flow to mid-eccentricity biased high-order visual cortex, adversely affecting its development and consequently inducing visual perceptual deficits predominantly for categories associated with these regions.

Prevalence of Face Recognition Deficits in Middle Childhood

Approximately 2–2.5% of the adult population is believed to show severe difficulties with face recognition, in the absence of any neurological injury—a condition known as developmental prosopagnosia (DP). However, to date no research has attempted to estimate the prevalence of face recognition deficits in children, possibly because there are very few child-friendly, well-validated tests of face recognition. In the current study, we examined face and object recognition in a group of primary school children (aged 5–11 years), to establish whether our tests were suitable for children and to provide an estimate of face recognition difficulties in children. In Experiment 1 ( n = 184), children completed a pre-existing test of child face memory, the Cambridge Face Memory Test–Kids (CFMT-K), and a bicycle test with the same format. In Experiment 2 ( n = 413), children completed three-alternative forced-choice matching tasks with faces and bicycles. All tests showed good psychometric properties. The face and bicycle tests were well matched for difficulty and showed a similar developmental trajectory. Neither the memory nor the matching tests were suitable to detect impairments in the youngest groups of children, but both tests appear suitable to screen for face recognition problems in middle childhood. In the current sample, 1.2–5.2% of children showed difficulties with face recognition; 1.2–4% showed face-specific difficulties—that is, poor face recognition with typical object recognition abilities. This is somewhat higher than previous adult estimates: It is possible that face matching tests overestimate the prevalence of face recognition difficulties in children; alternatively, some children may “outgrow” face recognition difficulties.

Functional development of the brain's face-processing system

In the first 20 years of life, the human brain undergoes tremendous growth in size, weight, and synaptic connectedness. Over the same time period, a person achieves remarkable transformations in perception, thought, and behavior. One important area of development is face processing ability, or the ability to quickly and accurately extract extensive information about a person's identity, emotional state, attractiveness, intention, and numerous other types of information that are crucial to everyday social interaction and communication. Associating particular brain changes with specific behavioral and intellectual developments has historically been a serious challenge for researchers. Fortunately, modern neuroimaging is dramatically advancing our ability to make associations between morphological and behavioral developments. In this article, we demonstrate how neuroimaging has revolutionized our understanding of the development of face processing ability to show that this essential perceptual and cognitive skill matures consistently yet slowly over the first two decades of life. In this manner, face processing is a model system of many areas of complex cognitive development. WIREs Cogn Sci 2017, 8:e1423. doi: 10.1002/wcs.1423 For further resources related to this article, please visit the WIREs website.

Perceptual Learning of Faces: A Rehabilitative Study of Acquired Prosopagnosia

Despite many studies of acquired prosopagnosia, there have been only a few attempts at its rehabilitation, all in single cases, with a variety of mnemonic or perceptual approaches, and of variable efficacy. In a cohort with acquired prosopagnosia, we evaluated a perceptual learning program that incorporated variations in view and expression, which was aimed at training perceptual stages of face processing with an emphasis on ecological validity. Ten patients undertook an 11-week face training program and an 11-week control task. Training required shape discrimination between morphed facial images, whose similarity was manipulated by a staircase procedure to keep training near a perceptual threshold. Training progressed from blocks of neutral faces in frontal view through increasing variations in view and expression. Whereas the control task did not change perception, training improved perceptual sensitivity for the trained faces and generalized to new untrained expressions and views of those faces. There was also a significant transfer to new faces. Benefits were maintained over a 3-month period. Training efficacy was greater for those with more perceptual deficits at baseline. We conclude that perceptual learning can lead to persistent improvements in face discrimination in acquired prosopagnosia. This reflects both acquisition of new skills that can be applied to new faces as well as a degree of overlearning of the stimulus set at the level of 3-D expression-invariant representations.

Impairments in the Face-Processing Network in Developmental Prosopagnosia and Semantic Dementia

BACKGROUND

Developmental prosopagnosia (DP) and semantic dementia (SD) may be the two most common neurologic disorders of face processing, but their main clinical and pathophysiologic differences have not been established. To identify those features, we compared patients with DP and SD.

METHODS

Five patients with DP, five with right temporal-predominant SD, and ten normal controls underwent cognitive, visual perceptual, and face-processing tasks.

RESULTS

Although the patients with SD were more cognitively impaired than those with DP, the two groups did not differ statistically on the visual perceptual tests. On the face-processing tasks, the DP group had difficulty with configural analysis and they reported relying on serial, feature-by-feature analysis or awareness of salient features to recognize faces. By contrast, the SD group had problems with person knowledge and made semantically related errors. The SD group had better face familiarity scores, suggesting a potentially useful clinical test for distinguishing SD from DP.

CONCLUSIONS

These two disorders of face processing represent clinically distinguishable disturbances along a right hemisphere face-processing network: DP, characterized by early configural agnosia for faces, and SD, characterized primarily by a multimodal person knowledge disorder. We discuss these preliminary findings in the context of the current literature on the face-processing network; recent studies suggest an additional right anterior temporal, unimodal face familiarity-memory deficit consistent with an "associative prosopagnosia."

Guidelines for studying developmental prosopagnosia in adults and children

Developmental prosopagnosia (DP) is a neurodevelopmental condition characterized by severe face identity recognition problems that results from a failure to develop the mechanisms necessary for adequate face processing (Duchaine BC, Nakayama K. Developmental prosopagnosia: a window to content-specific face processing. Curr Opin Neurobiol 2006, 16:166-173.). It occurs in children and adults with normal visual acuity, and without intellectual impairments or known brain injuries. Given the importance of face recognition in daily life, and the detrimental effects of impaired face recognition, DP is an important area of study. Yet conventions for classifying individuals as DP for research purposes are poorly defined. In this focus paper, we discuss: (1) criteria for an operational definition of DP; 2) tests of face recognition and conventions for classifying individuals as DP; and 3) important considerations regarding common associations and dissociations, and cognitive heterogeneity in DP. We also highlight issues unique to studying DP in children, a relatively new endeavor that is proving to be an important complement to the work with adults. Ultimately, we hope to identify challenges researchers face when studying DP, and offer guidelines for others to consider when embarking on their own research pursuits on the topic. For further resources related to this article, please visit the WIREs website.

Evolutionary Psychology as a Metatheory for the Social Sciences: How to Gather Interdisciplinary Evidence for a Psychological Adaptation

Evolutionary psychology has been proposed as a new metatheory for the social sciences ( Buss, 1995 ). Evolutionary psychology is an approach that emphasizes the evolutionary background of psychological phenomena (e.g., cognition, motivation, perception), with the expectation that knowledge about this background enhances our understanding of the working of the present human mind. This proposal has met with both enthusiasm and criticism. An important criticism is that it is hard, if possible at all, to find empirical evidence for a hypothesized psychological adaptation. This criticism has been addressed with the proposal to build a nomological network of evidence around a hypothesized psychological adaptation ( Schmitt & Pilcher, 2004 ). In this article, we show that it is possible to use this nomological network of evidence to support the hypothesis that face recognition is an adaptation. We reviewed the literature on face recognition from different disciplines (psychology, medicine, neuroscience, genetics, primatology, and anthropology) and conclude that there is an extensive network of evidence for the proposed hypothesis. We argue that building a nomological network of evidence is a promising way to address several criticisms of evolutionary psychology, and that such a network can serve as a metatheoretical framework for the social sciences.

The 20-item prosopagnosia index (PI20): a self-report instrument for identifying developmental prosopagnosia

Self-report plays a key role in the identification of developmental prosopagnosia (DP), providing complementary evidence to computer-based tests of face recognition ability, aiding interpretation of scores. However, the lack of standardized self-report instruments has contributed to heterogeneous reporting standards for self-report evidence in DP research. The lack of standardization prevents comparison across samples and limits investigation of the relationship between objective tests of face processing and self-report measures. To address these issues, this paper introduces the PI20; a 20-item self-report measure for quantifying prosopagnosic traits. The new instrument successfully distinguishes suspected prosopagnosics from typically developed adults. Strong correlations were also observed between PI20 scores and performance on objective tests of familiar and unfamiliar face recognition ability, confirming that people have the necessary insight into their own face recognition ability required by a self-report instrument. Importantly, PI20 scores did not correlate with recognition of non-face objects, indicating that the instrument measures face recognition, and not a general perceptual impairment. These results suggest that the PI20 can play a valuable role in identifying DP. A freely available self-report instrument will permit more effective description of self-report diagnostic evidence, thereby facilitating greater comparison of prosopagnosic samples, and more reliable classification.

Face processing improvements in prosopagnosia: successes and failures over the last 50 years

Clinicians and researchers have widely believed that face processing cannot be improved in prosopagnosia. Though more than a dozen reported studies have attempted to enhance face processing in prosopagnosics over the last 50 years, evidence for effective treatment approaches has only begun to emerge. Here, we review the current literature on spontaneous recovery in acquired prosopagnosia (AP), as well as treatment attempts in acquired and developmental prosopagnosia (DP), differentiating between compensatory and remedial approaches. We find that for AP, rather than remedial methods, strategic compensatory training such as verbalizing distinctive facial features has shown to be the most effective approach (despite limited evidence of generalization). In children with DP, compensatory training has also shown some effectiveness. In adults with DP, two recent larger-scale studies, one using remedial training and another administering oxytocin, have demonstrated group-level improvements and evidence of generalization. These results suggest that DPs, perhaps because of their more intact face processing infrastructure, may benefit more from treatments targeting face processing than APs.

"A room full of strangers every day": the psychosocial impact of developmental prosopagnosia on children and their families

OBJECTIVE

Individuals with developmental prosopagnosia ('face blindness') have severe face recognition difficulties due to a failure to develop the necessary visual mechanisms for recognizing faces. These difficulties occur in the absence of brain damage and despite normal low-level vision and intellect. Adults with developmental prosopagnosia report serious personal and emotional consequences from their inability to recognize faces, but little is known about the psychosocial consequences in childhood. Given the importance of face recognition in daily life, and the potential for unique social consequences of impaired face recognition in childhood, we sought to evaluate the impact of developmental prosopagnosia on children and their families.

METHODS

We conducted semi-structured interviews with 8 children with developmental prosopagnosia and their parents. A battery of face recognition tests was used to confirm the face recognition impairment reported by the parents of each child. We used thematic analysis to develop common themes among the psychosocial experiences of the children and their parents.

RESULTS

Three themes were developed from the child reports: 1) awareness of their difficulties, 2) coping strategies, such as using non-facial cues to identify others, and 3) social implications, such as discomfort in, and avoidance of, social situations. These themes were paralleled by the parent reports and highlight the unique social and practical challenges associated with childhood developmental prosopagnosia.

CONCLUSION

Our findings indicate a need for increased awareness and treatment of developmental prosopagnosia to help these children manage their face recognition difficulties and to promote their social and emotional wellbeing.

Dissociation between face perception and face memory in adults, but not children, with developmental prosopagnosia

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Individuals with developmental prosopagnosia (DP) have impaired face recognition.

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In theory, DP could involve impaired face memory, impaired face perception, or both.

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Memory deficits were present in all of our child and adult DPs.

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All children, but less than half of the adults had impaired face perception.

Cognitive models propose that face recognition is accomplished through a series of discrete stages, including perceptual representation of facial structure, and encoding and retrieval of facial information. This implies that impaired face recognition can result from failures of face perception, face memory, or both. Studies of acquired prosopagnosia, autism spectrum disorders, and the development of normal face recognition support the idea that face perception and face memory are distinct processes, yet this distinction has received little attention in developmental prosopagnosia (DP). To address this issue, we tested the face perception and face memory of children and adults with DP. By definition, face memory is impaired in DP, so memory deficits were present in all participants. However, we found that all children, but only half of the adults had impaired face perception. Thus, results from adults indicate that face perception and face memory are dissociable, while the results from children provide no evidence for this division. Importantly, our findings raise the possibility that DP is qualitatively different in childhood versus adulthood. We discuss theoretical explanations for this developmental pattern and conclude that longitudinal studies are necessary to better understand the developmental trajectory of face perception and face memory deficits in DP.

The rehabilitation of face recognition impairments: a critical review and future directions

While much research has investigated the neural and cognitive characteristics of face recognition impairments (prosopagnosia), much less work has examined their rehabilitation. In this paper, we present a critical analysis of the studies that have attempted to improve face-processing skills in acquired and developmental prosopagnosia, and place them in the context of the wider neurorehabilitation literature. First, we examine whether neuroplasticity within the typical face-processing system varies across the lifespan, in order to examine whether timing of intervention may be crucial. Second, we examine reports of interventions in acquired prosopagnosia, where training in compensatory strategies has had some success. Third, we examine reports of interventions in developmental prosopagnosia, where compensatory training in children and remedial training in adults have both been successful. However, the gains are somewhat limited-compensatory strategies have resulted in labored recognition techniques and limited generalization to untrained faces, and remedial techniques require longer periods of training and result in limited maintenance of gains. Critically, intervention suitability and outcome in both forms of the condition likely depends on a complex interaction of factors, including prosopagnosia severity, the precise functional locus of the impairment, and individual differences such as age. Finally, we discuss future directions in the rehabilitation of prosopagnosia, and the possibility of boosting the effects of cognitive training programmes by simultaneous administration of oxytocin or non-invasive brain stimulation. We conclude that future work using more systematic methods and larger participant groups is clearly required, and in the case of developmental prosopagnosia, there is an urgent need to develop early detection and remediation tools for children, in order to optimize intervention outcome.

The Cambridge Face Memory Test for Children (CFMT-C): a new tool for measuring face recognition skills in childhood

Face recognition ability follows a lengthy developmental course, not reaching maturity until well into adulthood. Valid and reliable assessments of face recognition memory ability are necessary to examine patterns of ability and disability in face processing, yet there is a dearth of such assessments for children. We modified a well-known test of face memory in adults, the Cambridge Face Memory Test (Duchaine & Nakayama, 2006, Neuropsychologia, 44, 576-585), to make it developmentally appropriate for children. To establish its utility, we administered either the upright or inverted versions of the computerised Cambridge Face Memory Test - Children (CFMT-C) to 401 children aged between 5 and 12 years. Our results show that the CFMT-C is sufficiently sensitive to demonstrate age-related gains in the recognition of unfamiliar upright and inverted faces, does not suffer from ceiling or floor effects, generates robust inversion effects, and is capable of detecting difficulties in face memory in children diagnosed with autism. Together, these findings indicate that the CFMT-C constitutes a new valid assessment tool for children's face recognition skills.

Holistic face training enhances face processing in developmental prosopagnosia

Prosopagnosia has largely been regarded as an untreatable disorder. However, recent case studies using cognitive training have shown that it is possible to enhance face recognition abilities in individuals with developmental prosopagnosia. Our goal was to determine if this approach could be effective in a larger population of developmental prosopagnosics. We trained 24 developmental prosopagnosics using a 3-week online face-training program targeting holistic face processing. Twelve subjects with developmental prosopagnosia were assessed before and after training, and the other 12 were assessed before and after a waiting period, they then performed the training, and were then assessed again. The assessments included measures of front-view face discrimination, face discrimination with view-point changes, measures of holistic face processing, and a 5-day diary to quantify potential real-world improvements. Compared with the waiting period, developmental prosopagnosics showed moderate but significant overall training-related improvements on measures of front-view face discrimination. Those who reached the more difficult levels of training ('better' trainees) showed the strongest improvements in front-view face discrimination and showed significantly increased holistic face processing to the point of being similar to that of unimpaired control subjects. Despite challenges in characterizing developmental prosopagnosics' everyday face recognition and potential biases in self-report, results also showed modest but consistent self-reported diary improvements. In summary, we demonstrate that by using cognitive training that targets holistic processing, it is possible to enhance face perception across a group of developmental prosopagnosics and further suggest that those who improved the most on the training task received the greatest benefits.