A new approach to diagnosing and researching developmental prosopagnosia: Excluded cases are impaired too

This condition impacts every aspect of my life: A survey to understand the experience of living with developmental prosopagnosia

This mixed methods study examined the real-world experiences of living with developmental prosopagnosia (face blindness), a lifelong neurodevelopmental condition that severely affects the ability to recognise faces despite otherwise normal vision, IQ and memory. Twenty-nine UK based adults with confirmed face recognition difficulties completed an online survey describing and quantifying their experiences of living with poor face recognition. Although the majority (62%) of participants reported being able to recognise their immediate family, e.g., parent, partner, or child, strikingly 35% reported being unable to reliably recognise their immediate family members out of context. Even fewer (45%), reported always being able to recognise their three closest friends when encountering them unexpectedly, highlighting that DP commonly affects the recognition of highly familiar faces with whom individuals have close emotional relationships. Furthermore, participants who reported being able or unable to recognise their immediate family showed no significant difference in objective face memory ability. More than two thirds of participants (65.5%) reported being able to recognise fewer than 10 familiar faces (with the most common response being none), far below typical abilities. Thematic framework analysis highlighted how low public, professional, and employer awareness of developmental prosopagnosia presented challenges across multiple domains including seeking diagnosis, social and family relationships and workplaces. Driven largely by concerns about negative evaluation by others, most participants employed a range of highly effortful, though error prone, strategies to disguise and compensate for their face recognition difficulties. Some of the strategies described may help explain why many individuals can perform within typical norms on laboratory face processing tests despite their clear difficulties in everyday life and highlight the need for ecologically valid tests. Participants' highest priorities for future research were improved awareness of developmental prosopagnosia and interventions to improve their face recognition ability.

Exploring insight into unfamiliar face recognition ability: The case from developmental prosopagnosia

This study aims to explore the relationship between face processing ability and individuals' insight into that ability, with a particular focus on those who 'self-refer' as having face recognition difficulties; namely, individuals with developmental prosopagnosia (DP). Specifically, the study examines whether self-referred individuals represent a subpopulation with elevated levels of insight into their face recognition performance compared to the general population. Using Bayesian hierarchical modelling, we compared performance across the 'objective' Cambridge Face Memory Test (CFMT) and the 'subjective' 20-item Prosopagnosia Index (PI20) in self-referred DP individuals (N = 279) and normative populations (N = 1,344)-this statistical approach allows for flexible, probabilistic predictions about performance based on subjective insight and group membership, enabling more nuanced comparisons. Despite hypotheses that self-referring participants might demonstrate superior metacognitive insight, results showed no credible evidence of enhanced alignment between PI20 and CFMT measures in this group compared to normative samples. Overall, these findings underscore the limitations of current diagnostic tools, emphasizing the need for psychometric refinement to address measurement noise and improve the reliability of subjective self-assessments. This work contributes to understanding individual variability in cognitive insight and highlights the challenges of identifying DP based on subjective and objective alignment.

Individuals with developmental prosopagnosia tend to focus more evenly on facial features

The facial processing characteristics of developmental prosopagnosia (DP) have long been a focus of research. In this study, we used behavioral and eye movement techniques to explore the facial fixation characteristics of DP by comparing the fixation patterns during facial recognition between people with DP and control individuals. A mixed 2 (group: control, DP) × 3 (area of interest [AOI]: eyes, nose, mouth) experimental design was adopted, dividing faces into 3 AOIs: eyes, nose, and mouth. The behavioral results showed that facial recognition scores were lower in the DP group than in the control group. The eye movement results showed that the duration and number of eye and nose fixations were greater than those on the mouth in the control group; however, the duration and number of fixations on the eyes, nose, and mouth did not differ in the DP group. These results confirmed that the control group focused more on the eyes and nose when recognizing faces, whereas the DP group adopted a more even browsing pattern to focus on various facial features. Overall, the differences between the fixation patterns of the control group and the DP group were explored with the help of eye-tracking technology, which revealed that the fixation patterns of the DP group were more evenly spread across multiple facial features than those of the control group were, providing a new perspective for researchers to further explore the causes of DP and formulate effective intervention programs.

The inter-association between face processing, intelligence, and autistic-like nonverbal communication

The degree to which face processing abilities inter-relate, and associate with general intelligence, remains a contentious issue. Furthermore, poorer face processing abilities may be a result of reduced social interest associated with higher levels of trait-autism, consistent with the social motivation theory of autism. However, the association between multiple dimensions of face processing (i.e., a general face factor) and trait-autism, specifically autistic-like nonverbal communication, has not been estimated. Consequently, we administered four face processing ability tests (assessing face detection, the perception and memory of face identity, and expression recognition), four cognitive ability tests, and the Autism Quotient to a sample of 253 general community adults. Based on latent variable modelling, we identified a general face processing ability factor (f), and it was positively associated with general intelligence (g; λ = .48). We conclude that face processing abilities may be a candidate ability within the Cattell-Horn-Carroll model of intelligence. Moreover, face memory was positively associated with g (β = .31). We discuss the possibility of developmental prosopagnosia, i.e., deficits in face memory, being diagnosed as a learning disability. Furthermore, autistic-like nonverbal communication was a significant, negative predictor (β = -.45) of f, and g was neither a mediator nor suppressor of the effect. Finally, the unique effect between autistic-like nonverbal communication difficulties and face processing abilities, independently of intelligence, was considered in line with the social motivation theory of autism.

Rehabilitation and intervention of developmental and acquired prosopagnosia: A systematic review

Prosopagnosia is a neurological disorder; characterized by an impairment in facial recognition. It can occur from acquired prosopagnosia (occurring in approximately 5.6% of the population), or from developmental prosopagnosia (occurring in approximately 2% of the population). Despite the relatively high prevalence of prosopagnosia, there has been limited research into intervention for this condition. The current systematic review aimed to review the evidence base to aid the development of practice guidelines for clinicians working with impacted individuals. A systemic search identified 14 studies, 10 of which involved participants with developmental prosopagnosia, while the remaining studies involved participants with acquired prosopagnosia. Overall, the findings identified two strategies which produced significant improvement in face recognition in prosopagnosics. The first strategy involved a perceptual learning strategy (a restorative approach). While this strategy improved face processing abilities, the intervention was time-consuming and relied on specific software. The second strategy involved learned association of distinguishable facial features (a compensatory approach). This intervention produced improvements in face recognition and was quick to administer, however, the gains made were not generalisable to untrained faces. The current review identified a number of limitations in the existing literature, such as the lack of single-case experimental designs and randomized controlled trials, limited control for practice effects, and no consensus with regard to the assessment and diagnosis of prosopagnosia. This review highlighted the need for further research to inform practice guidelines.

EGEFACE: A new face memory test with static and dynamic images

Face memory is a crucial cognitive ability necessary for maintaining a healthy social life. Recent studies reveal large individual differences in face recognition ability. Face memory tests are used to evaluate this ability. The main purpose of this study was to develop a new face memory test (EGEFACE) addressing the limitations of existing tests using both static and dynamic stimuli to increase ecological validity; employing face recognition algorithms to adjust test difficulty; measuring face memory accuracy independently of response bias by including both target-absent and target-present trials and using ROC analysis; and developing a test to measure both ends of the face recognition ability spectrum. After building a new database of static and dynamic faces, we created three difficulty levels using a face recognition algorithm. We collected data from 703 participants in two steps and examined the internal consistency, split-half reliability, and item-total score correlations. The reliability analysis confirmed that both target-absent and target-present trials of EGEFACE were reliable. High EGEFACE performers scored near super recognizer levels on CFMT+, while low performers showed limited overlap with prosopagnosic-level performance on CFMT+, suggesting EGEFACE's sensitivity across different levels of face recognition ability. Overall, results indicated a moderate positive correlation between EGEFACE and CFMT+, showing that both tests assess similar cognitive skills, while a low to moderate correlation with KFMT suggests that EGEFACE measures cognitive ability that is related to yet distinct from face perception. The results suggest that EGEFACE shows promise as an ecologically valid and effective alternative tool for assessing individual differences in face memory.

Face naming and recollection represent key memory deficits in developmental prosopagnosia

Previous studies have found that face perception deficits do not fully account for the severity of face recognition deficits in developmental prosopagnosia (DP). Researchers have begun identifying deficient memory mechanisms such as impaired face recollection, but these findings require replication, and further characterization of additional memory deficits is necessary. Our goals were to replicate prior findings of face recollection impairment in DP and extend these findings to assess different types of face associative memory. We had 69 DPs and 99 controls perform a face perception battery as well as three face memory tasks: 1) Old/New task with confidence ratings to calculate recollection and familiarity using ROC analysis, 2) Face/Scene task to examine remember-know judgments and contextual memory for faces, and 3) Face-Name/Occupation task to assess the ability to learn semantic associations with faces. Compared to controls, DPs showed poorer recollection and familiarity across both Old/New and Face/Scene tasks as well as reduced scene accuracy for correct faces. Of these differences, only Old/New recollection remained significant after controlling for group differences in face perception abilities. In the Face-Name/Occupation task, after controlling for face perception, DPs showed poorer recall of names than controls but performed similarly in recalling occupations. Finally, we found that DPs with major, mild, and no face perception deficits showed consistent impairments in Old/New recollection and face-naming, and larger perceptual deficits were associated with larger memory deficits. Together, these results provide several mechanistic insights into the nature of memory deficits in DPs and have diagnostic and treatment implications.

Poor face recognition predicts social anxiety in autism: A short report

LAY ABSTRACT

Research has shown that some autistic people have severe difficulties in recognising other people's faces. However, little is understood about how these difficulties impact the daily life and the mental well-being of autistic people. In this study, we asked 60 autistic adults with varying degrees of face recognition ability to complete two tests of face recognition, a questionnaire about social anxiety and a bespoke survey which asked participants about their experiences of face recognition and social interaction. We found that participants who had poor face recognition reported experiencing higher levels of social anxiety compared to those with average or better face recognition skills. More than half felt that their face recognition difficulties affected their social interactions, and over a third believed it hindered their ability to make friends. These findings suggest that face recognition difficulties may contribute to social anxiety among autistic individuals.

Improving the DSM-5 approach to cognitive impairment: Developmental prosopagnosia reveals the need for tailored diagnoses

The Diagnostic Statistical Manual of Mental Disorders (DSM-5) recommends diagnosing neurocognitive disorders (i.e., cognitive impairment) when a patient scores beyond - 1 SD below neurotypical norms on two tests. I review how this approach will fail due to cognitive tests' power limitations, validity issues, imperfect reliabilities, and biases, before summarizing their resulting negative consequences. As a proof of concept, I use developmental prosopagnosia, a condition characterized by difficulties recognizing faces, to show the DSM-5 only diagnoses 62-70% (n1 = 61, n2 = 165) versus 100% (n1 = 61) through symptoms alone. Pooling the DSM-5 missed cases confirmed the presence of group-level impairments on objective tests, which were further evidenced through meta-analyses, thus validating their highly atypical symptoms. These findings support a paradigm shift towards bespoke diagnostic approaches for distinct cognitive impairments, including a symptom-based method when validated effective. I reject dogmatic adherence to the DSM-5 approach to neurocognitive disorders, and underscore the importance of a data driven, transdiagnostic approach to understanding patients' subjective cognitive impairments. This will ultimately benefit patients, their families, clinicians, and scientific progress.

Impaired Face Feature-to-Location Statistical Learning and Single-Feature Discrimination in Developmental Prosopagnosia

Individuals with developmental prosopagnosia (DP) experience severe face memory deficits that are often accompanied by impairments in face perception. Images of human facial features are better discriminated between when they are presented in the locations on the visual field that they typically appear in while viewing human faces in daily life, than in locations which they do not typically appear (i.e., better performance for eyes in the upper visual field, and better performance for mouths in the lower visual field). These feature-to-location tuning effects (FLEs) can be explained by a retinotopically organised visual statistical learning mechanism. We had a large group of DP participants (N = 64), a control group (N = 74) and a group of individuals with a mild form of DP (N = 58) complete a single-feature discrimination task to determine whether face perception deficits in DP can be accounted for by an impairment in face feature-to-location tuning. The results showed that individuals with DP did not have significant FLEs, suggesting a marked impairment in the underlying visual statistical learning mechanism. In contrast, the mild DP group showed normal FLE effects which did not differ from the control group. Both DP groups had impaired single-feature processing (SFP) as compared to the control group. We also examined the effects of age on FLEs and SFP.

Autistic adults have insight into their relative face recognition ability

The PI20 is a self-report questionnaire that assesses the presence of lifelong face recognition difficulties. The items on this scale ask respondents to assess their face recognition ability relative to the rest of the population, either explicitly or implicitly. Recent reports suggest that the PI20 scores of autistic participants exhibit little or no correlation with their performance on the Cambridge Face Memory Test-a key measure of face recognition ability. These reports are suggestive of a meta-cognitive deficit whereby autistic individuals are unable to infer whether their face recognition is impaired relative to the wider population. In the present study, however, we observed significant correlations between the PI20 scores of 77 autistic adults and their performance on two variants of the Cambridge Face Memory Test. These findings indicate that autistic individuals can infer whether their face recognition ability is impaired. Consistent with previous research, we observed a wide spread of face recognition abilities within our autistic sample. While some individuals approached ceiling levels of performance, others met the prevailing diagnostic criteria for developmental prosopagnosia. This variability showed little or no association with non-verbal intelligence, autism severity, or the presence of co-occurring alexithymia or ADHD.

Disentangling developmental prosopagnosia: A scoping review of terms, tools and topics

The goal of this preregistered scoping review is to create an overview of the research on developmental prosopagnosia (DP). Through analysis of all empirical studies of DP in adults, we investigate 1) how DP is conceptualized and defined, 2) how individuals are classified with DP and 3) which aspects of DP are investigated in the literature. We reviewed 224 peer-reviewed studies of DP. Our analysis of the literature reveals that while DP is predominantly defined as a lifelong face recognition impairment in the absence of acquired brain injury and intellectual/cognitive problems, there is far from consensus on the specifics of the definition with some studies emphasizing e.g., deficits in face perception, discrimination and/or matching as core characteristics of DP. These differences in DP definitions is further reflected in the vast heterogeneity in classification procedures. Only about half of the included studies explicitly state how they classify individuals with DP, and these studies adopt 40 different assessment tools. The two most frequently studied aspects of DP are the role of holistic processing and the specificity of face processing, and alongside a substantial body of neuroimaging studies of DP, this paints a picture of a research field whose scientific interests and aims are rooted in cognitive neuropsychology and neuroscience. We argue that these roots - alongside the heterogeneity in DP definition and classification - may have limited the scope and interest of DP research unnecessarily, and we point to new avenues of research for the field.

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.

Cognitive strengths in neurodevelopmental disorders, conditions and differences: A critical review

Neurodevelopmental disorders are traditionally characterised by a range of associated cognitive impairments in, for example, sensory processing, facial recognition, visual imagery, attention, and coordination. In this critical review, we propose a major reframing, highlighting the variety of unique cognitive strengths that people with neurodevelopmental differences can exhibit. These include enhanced visual perception, strong spatial, auditory, and semantic memory, superior empathy and theory of mind, along with higher levels of divergent thinking. Whilst we acknowledge the heterogeneity of cognitive profiles in neurodevelopmental conditions, we present a more encouraging and affirmative perspective of these groups, contrasting with the predominant, deficit-based position prevalent throughout both cognitive and neuropsychological research. In addition, we provide a theoretical basis and rationale for these cognitive strengths, arguing for the critical role of hereditability, behavioural adaptation, neuronal-recycling, and we draw on psychopharmacological and social explanations. We present a table of potential strengths across conditions and invite researchers to systematically investigate these in their future work. This should help reduce the stigma around neurodiversity, instead promoting greater social inclusion and significant societal benefits.

The heterogeneity of holistic processing profiles in developmental prosopagnosia: holistic processing is impaired but not absent

Although it is generally assumed that face recognition relies on holistic processing, whether face recognition deficits observed in Developmental Prosopagnosics (DPs) can be explained by impaired holistic processing is currently under debate. The mixed findings from past studies could be the consequence of DP's heterogeneous deficit nature and the use of different measures of holistic processing-the inversion, part-whole, and composite tasks-which showed a poor association among each other. The present study aimed to gain further insight into the role of holistic processing in DPs. Groups of DPs and neurotypicals completed three tests measuring holistic face processing and non-face objects (i.e., Navon task). At a group level, DPs showed (1) diminished, but not absent, inversion and part-whole effects, (2) comparable magnitudes of the composite face effect and (3) global precedence effect in the Navon task. However, single-case analyses showed that these holistic processing deficits in DPs are heterogeneous.

Relationship between face recognition ability and anxiety tendencies in healthy young individuals: A prosopagnosia index and state-trait anxiety inventory study

Developmental prosopagnosia (DP) is a condition that indicates the inability to recognize individuals by their faces from birth, without any history of brain damage. The assessment of face recognition ability and diagnosis of DP involve the use of face tests such as the Cambridge Face Memory Test (CFMT) and the Cambridge Face Perception Test, along with self-reported measures like the 20-Item Prosopagnosia Index (PI20). Face recognition accuracy is affected by anxiety. However, previous studies on the relationship between face recognition ability and anxiety have not used the PI20 measure. This study aimed to investigate the relationship between self-reported measures of face recognition ability and anxiety tendencies among healthy young individuals for DP diagnosis and its implications. We used a face recognition test, involving the PI20, CFMT, Visual Perception Test for Agnosia-Famous Face Test (VPTA-FFT), and State-Trait Anxiety Inventory (STAI). We assessed the performance of 116 Japanese young adults (75 females, median age of 20.7 years, with a standard deviation of 1.2). Subsequently, we conducted a statistical analysis to examine the relationship between the outcomes of the face recognition tests and STAI scores using Pearson correlation analysis and single correlation coefficients. The results showed a positive correlation between state anxiety and PI20 (r = 0.308, p = 0.007), and a weak positive correlation was also observed between trait anxiety and PI20 (r = 0.268, p = 0.04). In contrast, there was no correlation between CFMT and VPTA-FFT with respect to STAI. The results of the hierarchical multiple regression analysis also suggested that the correlation between the performance on the PI20 (self-report) and objective measures of face recognition performance (the CFMT and the VPTA-FFT) are driven by differences in anxiety. This study is the first to explore the relationship between face recognition abilities and anxiety using the PI20 self-report measure. There are implications for future research on the diagnosis of DP and the relationship between anxiety and face recognition.

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.

Both identity and non-identity face perception tasks predict developmental prosopagnosia and face recognition ability

Developmental prosopagnosia (DP) is characterised by deficits in face identification. However, there is debate about whether these deficits are primarily perceptual, and whether they extend to other face processing tasks (e.g., identifying emotion, age, and gender; detecting faces in scenes). In this study, 30 participants with DP and 75 controls completed a battery of eight tasks assessing four domains of face perception (identity; emotion; age and gender; face detection). The DP group performed worse than the control group on both identity perception tasks, and one task from each other domain. Both identity perception tests uniquely predicted DP/control group membership, and performance on two measures of face memory. These findings suggest that deficits in DP may arise from issues with face perception. Some non-identity tasks also predicted DP/control group membership and face memory, even when face identity perception was accounted for. Gender perception and speed of face detection consistently predicted unique variance in group membership and face memory; several other tasks were only associated with some measures of face recognition ability. These findings indicate that face perception deficits in DP may extend beyond identity perception. However, the associations between tasks may also reflect subtle aspects of task demands or stimuli.

A new way of classifying developmental prosopagnosia: Balanced Integration Score

Despite severe everyday problems recognising faces, some individuals with developmental prosopagnosia (DP) can achieve typical accuracy scores on laboratory face recognition tests. To address this, studies sometimes also examine response times (RTs), which tend to be longer in DPs relative to control participants. In the present study, 24 potential (according to self-report) DPs and 110 age-matched controls completed the Cambridge Face and Bicycle Memory Tests, old new faces task, and a famous faces test. We used accuracy and the Balanced Integration Score (BIS), a measure that adjusts accuracy for RTs, to classify our sample at the group and individual levels. Subjective face recognition ability was assessed using the PI20 questionnaire and semi structured interviews. Fifteen DPs showed a major impairment using BIS compared with only five using accuracy alone. Logistic regression showed that a model incorporating the BIS measures was the most sensitive for classifying DP and showed highest area under the curve (AUC). Furthermore, larger between-group effect sizes were observed for a derived global (averaged) memory measure calculated using BIS versus accuracy alone. BIS is thus an extremely sensitive novel measure for attenuating speed-accuracy trade-offs that can otherwise mask impairment measured only by accuracy in DP.

Prosopagnosia Due to Metastatic Brain Tumor: A Case-Based Review

Prosopagnosia, also referred to as "face blindness," is a type of visual agnosia characterized by a decreased capacity to recognize familiar faces with a preserved ability to identify individuals based on non-facial visual traits or voice. Prosopagnosia can be categorized as developmental (DP) or acquired (AP) owing to a variety of underlying conditions, including trauma, neurodegenerative diseases, stroke, neuroinfections, and, less frequently, malignancies. Facial recognition is a complex process in which different neuronal networks are involved. The infrequent but notable higher visual-processing abnormalities can be caused by lesions of the inferior longitudinal fasciculus (ILF) in the non-dominant temporal lobe. We report a rare case of AP in a 69-year-old patient who is right-hand dominant with rectal carcinoma cerebral metastases. The patient complained of dizziness, vertigo, falls, and trouble recognizing her family members' faces. The CT scan of the head with contrast revealed two metastatic brain lesions with vasogenic edema, as one of them was in the right cerebellar hemisphere, causing dislocation and compression of the ILF. Corticosteroids and osmotherapy were utilized as a conservative treatment approach, which resulted in the prosopagnosia being completely withdrawn. In conclusion, patients with primary brain tumors or metastatic disease rarely present with an isolated cognitive deficit such as prosopagnosia. Based on the anatomical features and the personalized approach, a conservative or surgical approach may be useful to improve higher cortical functioning.

Evidence for a Classical Dissociation between Face and Object Recognition in Developmental Prosopagnosia

It is still a matter of debate whether developmental prosopagnosia is a disorder selective to faces or whether object recognition is also affected. In a previous study, based on a small sample of developmental prosopagnosics (DPs; N = 10), we found impairments in both domains although the difficulties were most pronounced for faces. Importantly, impairments with faces and objects were systematically related. We suggested that that the seemingly disproportional impairment for faces in DP was likely to reflect differences between stimulus categories in visual similarity. Here, we aimed to replicate these findings in a larger, independent sample of DPs (N = 21) using the same experimental paradigms. Contrary to our previous results, we found no disproportional effect of visual similarity on performance with faces or objects in the new DP group when compared to controls (N = 21). The new DP group performed within the control range, and significantly better than the old DP-group, on sensitive and demanding object recognition tasks, and we can demonstrate a classical dissociation between face and object recognition at the group level. These findings are perhaps the strongest evidence yet presented for a face-specific deficit in developmental prosopagnosia.

Diversity of aphantasia revealed by multiple assessments of visual imagery, multisensory imagery, and cognitive style

Aphantasia-a condition wherein individuals have a reduced or absent construction of voluntary visual imagery-is diagnosed using either the Vividness of Visual Imagery Questionnaire (VVIQ) or self-identification. However, a significant discrepancy exists between the proportions of aphantasia in the populations assessed using these two criteria. It is unclear why the reported proportions differ excessively and what percentage of people cannot form visual imagery. We investigated the replicability of the proportion of people with aphantasia using both criteria in the same population of participants. Therefore, we explored the potential causes of the discrepancy and characteristics of putative aphantasia in terms of multisensory imagery, cognitive style, and face recognition ability. First, we conducted an online sampling study (Study 1: N = 2,871) using the VVIQ, self-identification of a reduction in visual imagery, Questionnaire upon Mental Imagery (QMI), and Verbalizer-Visualizer Questionnaire (VVQ). We found that 3.7 and 12.1% fulfilled the VVIQ and self-identification criteria, respectively, roughly replicating the proportions reported in previous studies. The self-identification criterion-but not the VVIQ criterion-contains items related to face recognition; hence, we suspected that face recognition ability was factor contributing to this discrepancy and conducted another online sampling study (Study 2: N = 774). We found a significant correlation between VVIQ and face recognition ability in the control group with self-identification, but not in the group defined by low VVIQ (VVIQ ≤32). As the participants in the control group with self-identification tended to exhibit moderately high VVIQ scores but low face recognition ability, we reason that the discrepancy can be partially explained by the contamination of individual differences in face recognition ability. Additional analyses of Study 1 revealed that the aphantasia group included participants who lacked all types of sensory imagery or only visual imagery in multisensory imagery and exhibited a non-specific cognitive style. This study indicates that the VVIQ alone may be insufficient to diagnose individuals who report an inability to form visual imagery. Furthermore, we highlight the importance of multiple assessments-along with the VVIQ-to better understand the diversity of imagery in aphantasia.