Autism traits are common exclusionary criteria in developmental prosopagnosia (DP) studies. We investigated whether autism traits produce qualitatively diferent face processing in 43 DPs with high vs. low autism quotient (AQ) scores. Compared to controls (n=27), face memory and perception were similarly defcient in the high- and low-AQ DPs, with the high-AQ DP group additionally showing defcient face emotion recognition. Task-based fMRI revealed reduced occipito-temporal face selectivity in both groups, with high-AQ DPs additionally demonstrating decreased posterior superior temporal sulcus selectivity. Resting-state fMRI showed similar reduced face-selective network connectivity in both DP groups compared with controls. Together, this demonstrates that high- and low-AQ DP groups have very similar face processing defcits, with additional facial emotion defcits in high-AQ DPs.
Response times (RTs) are commonly used to assess cognitive abilities and have recently been employed to assess face and object recognition. However, it is unclear whether face and object processing RTs predict recognition ability beyond accuracy. To test the validity of RT as an assessment of face recognition ability, we examined accuracy and RT on a widely-used face matching assessment modified to collect meaningful RT data, the computerized Benton Face Recognition Test (BFRT-c), and measured whether they predict face recognition ability and DP vs. control group membership. 62 controls and 36 DPs performed the BFRT-c as well as validated measures of face recognition ability: the Cambridge Face Memory Test (CFMT) and a Famous Faces Memory Test (FFMT). We found little-to-no association between BFRT-c accuracy and RT in both controls (r=.07, p=.59) and DPs (r=.03, p=.86). In controls, BFRT-c accuracy robustly predicted CFMT performance (r=.49, p<.001), FFMT performance (r=.43, p<.001), and a CFMT-FFMT composite (r=.54, p<.001), whereas BFRT-c RT was not significantly associated with these measures (all r's<.16, p's>.21). We found that BFRT-c accuracy significantly differed between DPs and controls, but RT failed to differentiate the groups. Results in controls and DPs were replicated with outlier removal. Further, combined scores of BFRT-c accuracy and RT (inverse efficiency score and balanced integration score) did not predict face recognition ability or DP vs. control group membership better than accuracy alone. These results suggest researchers should take caution when using RT to characterize individual differences in face processing or diagnose deficits in prosopagnosia.
The prevalence of developmental prosopagnosia (DP), lifelong face recognition deficits, is widely reported to be 2-2.5%. However, DP has been diagnosed in different ways across studies, resulting in differing prevalence rates. In the current investigation, we estimated the range of DP prevalence by administering well-validated objective and subjective face recognition measures to an unselected web-based sample of 3,116 18-55 year-olds and applying DP diagnostic cutoffs from the last 13 years. We found estimated prevalence rates ranged from 0.64-5.42% when using a z-score approach and 0.13- 2.95% when using a percentile approach, with the most commonly used cutoffs by researchers having a prevalence rate of .93% (z- score, .45% when using percentiles). We next used multiple cluster analyses to examine whether there was a natural grouping of poorer face recognizers but failed to find consistent grouping beyond those with generally above versus below average face recognition. Lastly, we investigated whether DP studies with more relaxed diagnostic cutoffs were associated with better performance on the Cambridge Face Perception Test. In a sample of 43 studies, there was no significant association between diagnostic strictness and DP face perception accuracy (Kendall’s tau-b correlation, τb=.176 z-score; τb=.111 percentiles). Together, these results suggest that researchers have used more conservative DP diagnostic cutoffs than the widely reported 2-2.5% prevalence. We discuss the strengths and weaknesses of using more inclusive cutoffs, such as identifying mild and major forms of DP based on DSM-5.
Numerous neurological, developmental, and psychiatric conditions demonstrate impaired face recognition, which can be socially debilitating. These impairments can be caused by either deficient face perception or face memory mechanisms. Though there are well-validated, sensitive measures of face memory impairments, it currently remains unclear which assessments best measure face perception impairments. A sensitive, validated face perception measure could help with diagnosing causes of face recognition deficits and be useful in characterizing individual differences in unimpaired populations. Here, we compared the computerized Benton Face Recognition Test (BFRT-c) and Cambridge Face Perception Test (CFPT) in their ability to differentiate developmental prosopagnosics (DPs, N = 30) and age-matched controls (N = 30). Participants completed the BFRT-c, CFPT, and two additional face perception assessments: the University of Southern California Face Perception Test (USCFPT) and a novel same/different face matching test (SDFMT). Participants were also evaluated on objective and subjective face recognition tasks including the Cambridge Face Memory Test, famous faces test, and Prosopagnosia Index-20. We performed a logistic regression with the perception tests predicting DP vs. control group membership and used multiple linear regressions to predict continuous objective and subjective face recognition memory. Our results show that the BFRT-c performed as well as, if not better than, the CFPT, and that both tests clearly outperformed the USCFPT and SDFMT. Further, exploratory analyses revealed that face lighting-change conditions better predicted DP group membership and face recognition abilities than viewpoint-change conditions. Together, these results support the combined use of the BFRT-c and CFPT to best assess face perception impairments.
Previous face matching studies provide evidence that matching same identity faces (match trials) and discriminating different face identities (non-match trials) rely on distinct processes. For example, instructional studies geared towards improving face matching in applied settings have often found selective improvements in match or non-match trials only. Additionally, a small study found that developmental prosopagnosics (DPs) have specific deficits in making match but not non-match judgments. In the current study, we sought to replicate this finding in DPs and examine how individual differences across DPs and controls in match vs. non-match performance relate to featural vs. holistic processing abilities. 43 DPs and 27 controls matched face images shown from similar front views or with varied lighting or viewpoint. Participants also performed tasks measuring featural (eyes/mouth) and holistic processing (part-whole task). We found that DPs showed worse overall matching performance than controls and that their relative match vs. non-match deficit depended on image variation condition, indicating that DPs do not consistently show match- or non-match-specific deficits. When examining the association between holistic and featural processing abilities and match vs. non-match trials in the entire group of DPs and controls, we found a very clear dissociation: Match trials significantly correlated with eye processing ability (r=.48) but not holistic processing (r=.11), whereas non-match trials significantly correlated with holistic processing (r=.32) but not eye processing (r=.03). This suggests that matching same identity faces relies more on eye processing while discriminating different faces relies more on holistic processing.
While age-related decline in face recognition memory is well established, the degree of decline in face perceptual abilities across the lifespan and their underlying mechanisms are incompletely characterized. In the current study, using the part-whole task, we sought to examine how age relates to facial feature discrimination ability and holistic face processing in a large sample of 3,341 online participants aged 18-69 years. We evaluated performance on the part-whole eye and mouth trials and the magnitude of the part-whole holistic advantage across the lifespan. We found that while discrimination of the eye region decreased beginning in the 50s, both mouth discrimination accuracy and the magnitude of the holistic advantage were stable with age. When investigating gender differences, we found that age-related declines in eye region accuracy were more pronounced in men than women, but this was not true for mouth accuracy or holistic processing. We discuss potential mechanistic explanations for this eye region-specific aging effect, including age-related hearing loss and its potential relationship with the age-related positivity effect.
Autism traits are commonly used as exclusionary criteria in studies of developmental prosopagnosia (DP). We investigated whether autism traits result in qualitatively different face processing in 43 DPs with high vs. low autism quotient (AQ) scores and 27 controls. Compared to controls, behavioral face recognition deficits were similar between the high and low AQ DP groups aside from worse emotion recognition in the high AQ DPs. Both DP groups showed reduced face selectivity in task-based fMRI, although higher AQ DPs showed decreased face selectivity in the posterior superior temporal sulcus. Resting-state fMRI showed similar face network connectivity between DP groups. This suggests that face processing is similar between the DP groups, with additional emotion processing deficits in higher AQ DPs.
Developmental prosopagnosia (DP) is characterized by severe facial recognition deficits, though it is currently debated whether only face-specific neural mechanisms are disrupted. A recent fMRI study found widespread decreases in category-selective (e.g., scene, body) regions in DPs (Jiahui et al., 2019), suggesting disruption may not be face-specific. To further evaluate neural deficits in DP, we scanned 23 DPs and 23 controls in task-based fMRI (dynamic localizer of faces/scenes/objects/bodies) and resting-state fMRI. In the task-based fMRI, DPs exhibited reduced face-selectivity across ventral face areas (anterior temporal lobe-ATL, fusiform face area-FFA, and occipital face area-OFA). This category-selectivity reduction was not found for scenes, bodies or objects in their respective regions, suggesting that the deficit of DP is limited to faces. Moreover, only the face area selectivity correlated with face recognition ability (average face-selectivity across OFA/FFA r= .37, p<.05), whereas scene, body, and objects area selectivity did not (all p’s>.4). This shows that our measure of face-selectivity reflects behavioral performance on face identification. In the resting-state fMRI, DPs showed reduced functional connectivity (FC) across most region pairs within the face network. While FC within the body network showed some mild reduction, this reduction was not observed for FC within the scene or object network. Moreover, only the FC in the face network correlated with face recognition ability (average face-network FC r=.46, p<.001), while scene, body, and objects area FC did not (all p’s>.13). This suggests that only resting connectivity between face regions is related to face recognition ability. Interestingly, we do not find a significant correlation between face-selectivity and face-network FCs, indicating they explain independent variance in face-recognition ability. Together, the fMRI selectivity and FC results, as well as their association with behavioral performance across all examined categories, suggests that DPs’ functional neural deficits are largely limited to the faces.
The issue of the face specificity of recognition deficits in developmental prosopagnosia (DP) is fundamental to the organization of high-level visual memory and has been increasingly debated in recent years. Previous DP investigations have found some evidence of object recognition impairments, but have almost exclusively used familiar objects (e.g. cars), where performance may depend on acquired object-specific experience and related visual expertise. An object recognition test not influenced by experience could provide a better, less contaminated measure of DPs' object recognition abilities. To investigate this, in the current study we tested 30 DPs and 30 matched controls on a novel object memory test (NOMT Ziggerins) and the Cambridge Face Memory Test (CFMT). DPs with severe impairment on the CFMT showed no differences in accuracy or reaction times compared with controls on the NOMT. We found similar results when comparing DPs with a larger sample of 274 web-based controls. Additional individual analyses demonstrated that the rate of object recognition impairment in DPs did not differ from the rate of impairment in either control group. Together, these results demonstrate unimpaired object recognition in DPs for a class of novel objects that serves as a powerful index for broader novel object recognition capacity.
Converging lines of research suggests that many developmental prosopagnosics (DPs) have impairments beyond face perception, but currently no framework exists to characterize these impaired mechanisms. One potential extra-perceptual deficit is that DPs encode/retrieve faces in a distinct manner from controls that does not sufficiently support individuation. To test this possibility, 30 DPs and 30 matched controls performed an old/new face recognition task while providing confidence ratings, to which a model-based ROC analysis was applied. DPs had significantly reduced recollection compared to controls, driven by fewer ‘high-confidence target’ responses, but intact familiarity. Recollection and face perception ability uniquely predicted objective and subjective prosopagnosia symptoms, together explaining 51% and 56% of the variance, respectively. These results suggest that a specific deficit in face recollection in DP may represent a core aspect of the difficulty in confidently identifying an individual by their face.
Are gender differences in face recognition influenced by familiarity and socio-cultural factors? Previous studies have reported gender differences in processing unfamiliar faces, consistently finding a female advantage and a female own-gender bias. However, researchers have recently highlighted that unfamiliar faces are processed less efficiently than familiar faces, which have more robust, invariant representations. To-date, no study has examined whether gender differences exist for familiar face recognition. The current study addressed this by using a famous faces task in a large, web-based sample of > 2000 participants across different countries. We also sought to examine if differences varied by socio-cultural gender equality within countries. When examining raw accuracy as well when controlling for fame, the results demonstrated that there were no participant gender differences in overall famous face accuracy, in contrast to studies of unfamiliar faces. There was also a consistent own-gender bias in male but not female participants. In countries with low gender equality, including the USA, females showed significantly better recognition of famous female faces compared to male participants, whereas this difference was abolished in high gender equality countries. Together, this suggests that gender differences in recognizing unfamiliar faces can be attenuated when there is enough face learning and that sociocultural gender equality can drive gender differences in familiar face recognition.
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.
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.
Although holistic processing is thought to underlie normal face recognition ability, widely discrepant reports have recently emerged about this link in an individual differences context. Progress in this domain may have been impeded by the widespread use of subtraction scores, which lack validity due to their contamination with control condition variance. Regressing, rather than subtracting, a control condition from a condition of interest corrects this validity problem by statistically removing all control condition variance, thereby producing a specific measure that is uncorrelated with the control measure. Using 43 participants, we measured the relationships amongst the Cambridge Face Memory Test (CFMT) and two holistic processing measures, the composite task (CT) and the part-whole task (PW). For the holistic processing measures (CT and PW), we contrasted the results for regressing vs. subtracting the control conditions (parts for PW; misaligned congruency effect for CT) from the conditions of interest (wholes for PW; aligned congruency effect for CT). The regression-based holistic processing measures correlated with each other and with CFMT, supporting the idea of a unitary holistic processing mechanism that is involved in skilled face recognition. Subtraction scores yielded weaker correlations, especially for the PW. Together, the regression-based holistic processing measures predicted more than twice the amount of variance in CFMT (R2 = .21) than their respective subtraction measures (R2 = .10). We conclude that holistic processing is robustly linked to skilled face recognition. In addition to confirming this theoretically significant link, these results provide a case in point for the inappropriateness of subtraction scores when requiring a specific individual differences measure that removes the variance of a control task.