Cleaner fish recognize self in a mirror via self-face recognition like humans.

Some animals have the remarkable capacity for mirror self-recognition (MSR), yet any implications for self-awareness remain uncertain and controversial. This is largely because explicit tests of the two potential mechanisms underlying MSR are still lacking: mental image of the self and kinesthetic visual matching. Here, we test the hypothesis that MSR ability in cleaner fish, Labroides dimidiatus, is associated with a mental image of the self, in particular the self-face, like in humans. Mirror-naive fish initially attacked photograph models of both themselves and unfamiliar strangers. In contrast, after all fish had passed the mirror mark test, fish did not attack their own (motionless) images, but still frequently attacked those of unfamiliar individuals. When fish were exposed to composite photographs, the self-face/unfamiliar body were not attacked, but photographs of unfamiliar face/self-body were attacked, demonstrating that cleaner fish with MSR capacity recognize their own facial characteristics in photographs. Additionally, when presented with self-photographs with a mark placed on the throat, unmarked mirror-experienced cleaner fish demonstrated throat-scraping behaviors. When combined, our results provide clear evidence that cleaner fish recognize themselves in photographs and that the likely mechanism for MSR is associated with a mental image of the self-face, not a kinesthetic visual-matching model. Humans are also capable of having a mental image of the self-face, which is considered an example of private self-awareness. We demonstrate that combining mirror test experiments with photographs has enormous potential to further our understanding of the evolution of cognitive processes and private self-awareness across nonhuman animals.

A Unifying Model for Discordant and Concordant Results in Human Neuroimaging Studies of Facial Viewpoint Selectivity.

Recognizing faces regardless of their viewpoint is critical for social interactions. Traditional theories hold that view-selective early visual representations gradually become tolerant to viewpoint changes along the ventral visual hierarchy. Newer theories, based on single-neuron monkey electrophysiological recordings, suggest a three-stage architecture including an intermediate face-selective patch abruptly achieving invariance to mirror-symmetric face views. Human studies combining neuroimaging and multivariate pattern analysis (MVPA) have provided convergent evidence of view selectivity in early visual areas. However, contradictory conclusions have been reached concerning the existence in humans of a mirror-symmetric representation like that observed in macaques. We believe these contradictions arise from low-level stimulus confounds and data analysis choices. To probe for low-level confounds, we analyzed images from two face databases. Analyses of image luminance and contrast revealed biases across face views described by even polynomials-i.e., mirror-symmetric. To explain major trends across neuroimaging studies, we constructed a network model incorporating three constraints: cortical magnification, convergent feedforward projections, and interhemispheric connections. Given the identified low-level biases, we show that a gradual increase of interhemispheric connections across network-layers is sufficient to replicate view-tuning in early processing stages and mirror-symmetry in later stages. Data analysis decisions-pattern dissimilarity measure and data recentering-accounted for the inconsistent observation of mirror-symmetry across prior studies. Pattern analyses of human fMRI data (of either sex) revealed biases compatible with our model. The model provides a unifying explanation of MVPA studies of viewpoint selectivity and suggests observations of mirror-symmetry originate from ineffectively normalized signal imbalances across different face views.

The impact of bilateral versus unilateral anterior temporal lobe damage on face recognition, person knowledge and semantic memory.

The functional importance of the anterior temporal lobes (ATLs) has come to prominence in two active, albeit unconnected literatures-(i) face recognition and (ii) semantic memory. To generate a unified account of the ATLs, we tested the predictions from each literature and examined the effects of bilateral versus unilateral ATL damage on face recognition, person knowledge, and semantic memory. Sixteen people with bilateral ATL atrophy from semantic dementia (SD), 17 people with unilateral ATL resection for temporal lobe epilepsy (TLE; left = 10, right = 7), and 14 controls completed tasks assessing perceptual face matching, person knowledge and general semantic memory. People with SD were impaired across all semantic tasks, including person knowledge. Despite commensurate total ATL damage, unilateral resection generated mild impairments, with minimal differences between left- and right-ATL resection. Face matching performance was largely preserved but slightly reduced in SD and right TLE. All groups displayed the familiarity effect in face matching; however, it was reduced in SD and right TLE and was aligned with the level of item-specific semantic knowledge in all participants. We propose a neurocognitive framework whereby the ATLs underpin a resilient bilateral representation system that supports semantic memory, person knowledge and face recognition.

With childhood hemispherectomy, one hemisphere can support-but is suboptimal for-word and face recognition.

The right and left cerebral hemispheres are important for face and word recognition, respectively-a specialization that emerges over human development. The question is whether this bilateral distribution is necessary or whether a single hemisphere, be it left or right, can support both face and word recognition. Here, face and word recognition accuracy in patients (median age 16.7 y) with a single hemisphere following childhood hemispherectomy was compared against matched typical controls. In experiment 1, participants viewed stimuli in central vision. Across both face and word tasks, accuracy of both left and right hemispherectomy patients, while significantly lower than controls' accuracy, averaged above 80% and did not differ from each other. To compare patients' single hemisphere more directly to one hemisphere of controls, in experiment 2, participants viewed stimuli in one visual field to constrain initial processing chiefly to a single (contralateral) hemisphere. Whereas controls had higher word accuracy when words were presented to the right than to the left visual field, there was no field/hemispheric difference for faces. In contrast, left and right hemispherectomy patients, again, showed comparable performance to one another on both face and word recognition, albeit significantly lower than controls. Altogether, the findings indicate that a single developing hemisphere, either left or right, may be sufficiently plastic for comparable representation of faces and words. However, perhaps due to increased competition or "neural crowding," constraining cortical representations to one hemisphere may collectively hamper face and word recognition, relative to that observed in typical development with two hemispheres.

Artificial intelligence in cardiovascular medicine: clinical applications.

Clinical medicine requires the integration of various forms of patient data including demographics, symptom characteristics, electrocardiogram findings, laboratory values, biomarker levels, and imaging studies. Decision-making on the optimal management should be based on a high probability that the envisaged treatment is appropriate, provides benefit, and bears no or little potential harm. To that end, personalized risk-benefit considerations should guide the management of individual patients to achieve optimal results. These basic clinical tasks have become more and more challenging with the massively growing data now available; artificial intelligence and machine learning (AI/ML) can provide assistance for clinicians by obtaining and comprehensively preparing the history of patients, analysing face and voice and other clinical features, by integrating laboratory results, biomarkers, and imaging. Furthermore, AI/ML can provide a comprehensive risk assessment as a basis of optimal acute and chronic care. The clinical usefulness of AI/ML algorithms should be carefully assessed, validated with confirmation datasets before clinical use, and repeatedly re-evaluated as patient phenotypes change. This review provides an overview of the current data revolution that has changed and will continue to change the face of clinical medicine radically, if properly used, to the benefit of physicians and patients alike.

Rhythmic Information Sampling in the Brain during Visual Recognition.

When we fixate an object, visual information is continuously received on the retina. Several studies observed behavioral oscillations in perceptual sensitivity across such stimulus time, and these fluctuations have been linked to brain oscillations. However, whether specific brain areas show oscillations across stimulus time (i.e., different time points of the stimulus being more or less processed, in a rhythmic fashion) has not been investigated. Here, we revealed random areas of face images at random moments across time and recorded the brain activity of male and female human participants using MEG while they performed two recognition tasks. This allowed us to quantify how each snapshot of visual information coming from the stimulus is processed across time and across the brain. Oscillations across stimulus time (rhythmic sampling) were mostly visible in early visual areas, at theta, alpha, and low beta frequencies. We also found that they contributed to brain activity more than previously investigated rhythmic processing (oscillations in the processing of a single snapshot of visual information). Nonrhythmic sampling was also visible at later latencies across the visual cortex, either in the form of a transient processing of early stimulus time points or of a sustained processing of the whole stimulus. Our results suggest that successive cycles of ongoing brain oscillations process stimulus information incoming at successive moments. Together, these results advance our understanding of the oscillatory neural dynamics associated with visual processing and show the importance of considering the temporal dimension of stimuli when studying visual recognition.SIGNIFICANCE STATEMENT Several behavioral studies have observed oscillations in perceptual sensitivity over the duration of stimulus presentation, and these fluctuations have been linked to brain oscillations. However, oscillations across stimulus time in the brain have not been studied. Here, we developed an MEG paradigm to quantify how visual information received at each moment during fixation is processed through time and across the brain. We showed that different snapshots of a stimulus are distinctly processed in many brain areas and that these fluctuations are oscillatory in early visual areas. Oscillations across stimulus time were more prevalent than previously studied oscillations across processing time. These results increase our understanding of how neural oscillations interact with the visual processing of temporal stimuli.

Comparison with others influences encoding and recognition of their faces: Behavioural and ERP evidence.

In daily life, faces are often memorized within contexts involving interpersonal interactions. However, little is known about whether interpersonal interaction-related contexts influence face memory. The present study aimed to understand this question by investigating how social comparison-related context affects face encoding and recognition. To address this issue, 40 participants were informed that they and another player each played a monetary game and were then presented with both of their outcomes (either monetary gain or loss). Subsequently, participants were shown the face of the player whom they were just paired with. After all the faces had been encoded, participants were asked to perform a sudden old/new recognition task involving these faces. The results showed that, during the encoding phase, another player's monetary gain, compared to loss, resulted in more negative responses in the N170 and early posterior negativity (EPN)/N250 to relevant players' faces when participants encountered monetary loss and a smaller late positive potential (LPP) response irrespective of self-related outcomes. In the subsequent recognition phase, preceding another player's monetary gain as compared to loss led to better recognition performance and stronger EPN/N250 and LPP responses to the faces of relevant players when participants had lost some amount of money. These findings suggest that the social comparison-related context, particularly self-disadvantageous outcomes in the context, influences the memory of comparators' faces.

Face Processing Systems: From Neurons to Real-World Social Perception.

Primate face processing depends on a distributed network of interlinked face-selective areas composed of face-selective neurons. In both humans and macaques, the network is divided into a ventral stream and a dorsal stream, and the functional similarities of the areas in humans and macaques indicate they are homologous. Neural correlates for face detection, holistic processing, face space, and other key properties of human face processing have been identified at the single neuron level, and studies providing causal evidence have established firmly that face-selective brain areas are central to face processing. These mechanisms give rise to our highly accurate familiar face recognition but also to our error-prone performance with unfamiliar faces. This limitation of the face system has important implications for consequential situations such as eyewitness identification and policing.

The influence of time of day on memory recognition for faces.

Time of day can alter memory performance in general. Its influence on memory recognition performance for faces, which is important for daily encounters with new persons or testimonies, has not been investigated yet. Importantly, high levels of the stress hormone cortisol impair memory recognition, in particular for emotional material. However, some studies also reported high cortisol levels to enhance memory recognition. Since cortisol levels in the morning are usually higher than in the evening, time of day might also influence recognition performance. In this pre-registered study with a two-day design, 51 healthy men encoded pictures of male and female faces with distinct emotional expressions on day one around noon. Memory for the faces was retrieved two days later at two consecutive testing times either in the morning (high and moderately increased endogenous cortisol levels) or in the evening (low endogenous cortisol levels). Additionally, alertness as well as salivary cortisol levels at the different timepoints was assessed. Cortisol levels were significantly higher in the morning compared to the evening group as expected, while both groups did not differ in alertness. Familiarity ratings for female stimuli were significantly better when participants were tested during moderately increased endogenous cortisol levels in the morning than during low endogenous cortisol levels in the evening, a pattern which was previously also observed for stressed versus non-stressed participants. In addition, cortisol levels during that time in the morning were positively correlated with the recollection of face stimuli in general. Thus, recognition memory performance may depend on the time of day and as well as on stimulus type, such as the difference of male and female faces. Most importantly, the results suggest that cortisol may be meaningful and worth investigating when studying the effects of time of day on memory performance. This research offers both, insights into daily encounters as well as legally relevant domains as for instance testimonies.

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.

Altered dynamic network interactions in children with ASD during face recognition revealed by time-varying EEG networks.

Although the electrophysiological event-related potential in face processing (e.g. N170) is widely accepted as a face-sensitivity biomarker that is deficient in children with autism spectrum disorders, the time-varying brain networks during face recognition are still awaiting further investigation. To explore the social deficits in autism spectrum disorder, especially the time-varying brain networks during face recognition, the current study analyzed the N170, cortical activity, and time-varying networks under 3 tasks (face-upright, face-inverted, and house-upright) in autism spectrum disorder and typically developing children. The results revealed a smaller N170 amplitude in autism spectrum disorder compared with typically developing, along with decreased cortical activity mainly in occipitotemporal areas. Concerning the time-varying networks, the atypically stronger information flow and brain network connections across frontal, parietal, and temporal regions in autism spectrum disorder were reported, which reveals greater effort was exerted by autism spectrum disorder to obtain comparable performance to the typically developing children, although the amplitude of N170 was still smaller than that of the typically developing children. Different brain activation states and interaction patterns of brain regions during face processing were discovered between autism spectrum disorder and typically developing. These findings shed light on the face-processing mechanisms in children with autism spectrum disorder and provide new insight for understanding the social dysfunction of autism spectrum disorder.

Face recognition ability can be predicted by microstructural properties of white matter: a study of diffusion tensor imaging (DTI).

There is a great individual difference in people's face recognition ability (FRA). This study aimed to reveal the neural mechanism underlying such individual differences. Elastic-net regression models were constructed to predict FRA based on the white matter (WM) microstructural properties. We found that FRA can be accurately predicted by the WM microstructural properties. For the right inferior longitudinal fasciculus (ILF) and bilateral arcuate fasciculus (AF), FRA was correlated negatively to fractional anisotropy (FA), but positively to radial diffusivity (RD). In contrast, for the corpus callosum forceps minor (CFM), FRA was correlated positively to FA, but negatively to RD. Such various patterns of the WM microstructural properties suggested a positive correlation between FRA and fiber diameter for the right ILF and bilateral AF, but a negative correlation between FRA and diameter of the CFM. These findings reflected that FRA was correlated positively to connectivities of the right ILF and bilateral AF, but negatively to those of the CFM. These findings not only confirmed the significant role of the right ILF in face recognition, but also revealed the involvement of the bilateral AF and CFM in face recognition, particularly implying the important role of hemisphere lateralization modulated by transcallosal connectivity in face recognition.

Pupil dilation reflects covert familiar face recognition under interocular suppression.

In prosopagnosia, brain lesions impair overt face recognition, but not face detection, and may coexist with residual covert recognition of familiar faces. Previous studies that simulated covert recognition in healthy individuals have impaired face detection as well as recognition, thus not fully mirroring the deficits in prosopagnosia. We evaluated a model of covert recognition based on continuous flash suppression (CFS). Familiar and unfamiliar faces and houses were masked while participants performed two discrimination tasks. With increased suppression, face/house discrimination remained largely intact, but face familiarity discrimination deteriorated. Covert recognition was present across all masking levels, evinced by higher pupil dilation to familiar than unfamiliar faces. Pupil dilation was uncorrelated with overt performance across subjects. Thus, CFS can impede overt face recognition without disrupting covert recognition and face detection, mirroring critical features of prosopagnosia. CFS could be used to uncover shared neural mechanisms of covert recognition in prosopagnosic patients and neurotypicals.

Enfacement illusions: Filling a knowledge gap in eating disorder risk assessment, prevention, and intervention?

Body image disturbance (BID) is central to eating disorders (EDs), yet the role of self-face perception has received limited empirical attention despite rising sociocultural pressures emphasizing facial appearance through technologies such as social media. Emerging evidence suggests impairments in self-face recognition accuracy and distorted perceptions of facial appearance among individuals with EDs. Enfacement illusions, involving the experimental induction of perceived ownership over another's face, offer a novel paradigm to comprehensively investigate the perceptual multisensory integration processes underlying self-face perception disturbances in ED populations. Such an approach may hold promise for elucidating core pathological mechanisms contributing to BID and ED psychopathology. We discuss how rigorous investigation of self-face perception through the enfacement illusion paradigm represents an innovative direction of research and/or clinical application that may advance etiological models of EDs and possibly inform interventions targeting the potentially multidimensional nature of body and facial image disturbances characterizing EDs. PUBLIC SIGNIFICANCE STATEMENT: Body image disturbance is central to eating disorders (EDs), yet, the role of face-related disturbances remains critically under-investigated. After summarizing findings on face-related disturbances in EDs we propose how enfacement illusions (i.e., the experimental induction of ownership over another's face) may elucidate self-face perception disturbances in EDs, and their underlying mechanisms. Enfacement illusions may also offer an intervention to potentially address multifaceted face and body image disturbances characterizing EDs.

The 2024 Richardson Lecture: Prosopagnosia - A Classic Neurologic Deficit Meets the Modern Era.

Acquired prosopagnosia is a rare disorder, but it serves as a model for impairments in expert-level visual processing. This review discusses five key observations made over the past 30 years. First, there are variants, an apperceptive type linked to damage to the inferior occipitotemporal cortex and an amnestic type associated with anterior temporal lesions, both either right or bilateral. Second, these variants are clustered in syndromes with other perceptual deficits, the apperceptive type with field defects, dyschromatopsia and topographagnosia, and the amnestic type with topographagnosia and the auditory disorders of phonagnosia and acquired amusia. Third, extensive testing often shows additional problems with recognizing exemplars of other objects, especially when degrees of expertise are taken into account. Fourth, the prosopagnosic impairment does not affect all facial information. For example, the perception of expression and lip-reading likely depends on other neural substrates than those for processing facial identity. Last, face perception in prosopagnosia is not immutable but can improve with extensive training, though as yet this does not represent a cure for the condition. Continuing work with neural networks and animal models will enhance our understanding of this intriguing condition and what it tells us about how our brains process vision.

Building 3D Generative Models from Minimal Data.

We propose a method for constructing generative models of 3D objects from a single 3D mesh and improving them through unsupervised low-shot learning from 2D images. Our method produces a 3D morphable model that represents shape and albedo in terms of Gaussian processes. Whereas previous approaches have typically built 3D morphable models from multiple high-quality 3D scans through principal component analysis, we build 3D morphable models from a single scan or template. As we demonstrate in the face domain, these models can be used to infer 3D reconstructions from 2D data (inverse graphics) or 3D data (registration). Specifically, we show that our approach can be used to perform face recognition using only a single 3D template (one scan total, not one per person). We extend our model to a preliminary unsupervised learning framework that enables the learning of the distribution of 3D faces using one 3D template and a small number of 2D images. Our approach is motivated as a potential model for the origins of face perception in human infants, who appear to start with an innate face template and subsequently develop a flexible system for perceiving the 3D structure of any novel face from experience with only 2D images of a relatively small number of familiar faces.

Altered development of face recognition among infants born amid the COVID-19 pandemic.

To effectively contain the spread of COVID-19, public health agencies mandated special regulations. Although they protected us from COVID-19, these restrictions have inevitably changed the environment around us. It remains unclear how these changes may have affected early cognitive development among infants born during the pandemic. Thus, this study examined how the COVID-19 restrictions have affected infants' face recognition ability, a hallmark of their cognitive capacities. Specifically, we used the familiarization and visual pair comparison paradigm to examine face recognition performance among infants aged 6 to 14 months amid the second wave of the pandemic (February to July 2021). Experiment 1 investigated the recognition of unmasked faces and found that only younger infants, but not older infants, recognized faces by showing a novelty preference. Experiment 2 examined the recognition of faces wearing masks and found that only older infants, but not younger ones, recognized faces by exhibiting a familiarity preference. These results suggest that with limited interactions during the pandemic, infants could have developed an overly specialized face processing ability that failed to recognize the faces of strangers. Moreover, infants could have obtained more information on masked faces during the pandemic and adapted to the current situation. In Expreiment 3, we further confirmed the restriction on infants' interpersonal experiences with a survey conducted both before and during the pandemic. Overall, these findings demonstrated how the pandemic altered early perceptual development and further confirmed that interpersonal experiences during infancy are critical in their cognitive development.

A reflection on faces seen under mirror reversal.

Much of our visual experience of faces, including our own, is mediated by technology, for example when a digital photo depicts a mirror reversal of reality. How does this difference in visual experience affect judgments about appearance? Here, we asked participants to view their likeness in photographs that were reversed (as when viewed in a mirror) or not reversed (as when viewed directly). Observers also perceptually adapted (or not) to the reversed or non-reversed images in a 2 × 2 design. Observers then rated how much each photograph resembled them and how much they liked their appearance in the photograph, later repeating the procedure for images of close friends. We found that non-reversed images are perceived as more "unlike" one's self and less pleasant than reversed images; the pattern disappears when evaluating close friends, where the non-reversed image is the more familiar, with adaptation having asymmetric effects. Experiment 1A was fully replicated seven years later. These results are likely driven by a strong, albeit malleable, visual representation of self, born of technology mediated experience and activated when an unfamiliar perspective exposes facial asymmetries. We conclude by considering the downstream effects of these preferences on consumer and social behavior.

Multiple images captured from a single encounter do not promote face learning.

Viewing multiple images of a newly encountered face improves recognition of that identity in new instances. Studies examining face learning have presented high-variability (HV) images that incorporate changes that occur from moment-to-moment (e.g., head orientation and expression) and over time (e.g., lighting, hairstyle, and health). We examined whether low-variability (LV) images (i.e., images that incorporate only moment-to-moment changes) also promote generalisation of learning such that novel instances are recognised. Participants viewed a single image, six LV images, or six HV images of a target identity before being asked to recognise novel images of that identity in a face matching task (training stimuli remained visible) or a memory task (training stimuli were removed). In Experiment 1 (n = 71), participants indicated which image(s) in 8-image arrays belonged to the target identity. In Experiment 2 (n = 73), participants indicated whether sequentially presented images belonged to the target identity. Relative to the single-image condition, sensitivity to identity improved and response biases were less conservative in the HV condition; we found no evidence of generalisation of learning in the LV condition regardless of testing protocol. Our findings suggest that day-to-day variability in appearance plays an essential role in acquiring expertise with a novel face.

Malocclusion or laterorhinia: Which one impacts aesthetic facial perception the most?

INTRODUCTION: This study aimed to evaluate the perception of facial attractiveness when nose and teeth, together or isolated, present different degrees of disharmony. The secondary objective was to compare the perception of laypersons with that of dentists. MATERIALS AND METHODS: This cross-sectional observational study included 112 individuals (58 laypersons and 54 dentists) that evaluated 6 manipulated images of the face of the same model, scoring their attractiveness using 10 cm Visual Analogue Scales (VAS), with least and most attractive at the left and right anchors, respectively. The images contained manipulations performed only on the nose (laterorhinia) and mouth (misaligned teeth), as follows: (1) standard photograph, with symmetrical nose + aligned teeth; (2) 2 mm nasal deviation + aligned teeth; (3) 4 mm nasal deviation + aligned teeth; (4) symmetrical nose + misaligned teeth; (5) 2 mm nasal deviation + misaligned teeth and (6) 4 mm nasal deviation + misaligned teeth. We used the repeated measures ANOVA test and Tukey's post-test for intra-group comparison of the images. The independent t-test was used for inter-group comparison of each image. RESULTS: In the laypersons' group, the highest grades were given to images with aligned teeth and the lowest to misaligned teeth (smallest mean difference = 2.88 cm). For this group, there was no statistically significant difference (P-values ranged from .988 to 1.000) between scores of the three images in which teeth were aligned (range of 7.70-7.78 cm). In the group of dentists, highest grades were given to images with aligned teeth and the lowest to misaligned teeth. Difference between images 3 and 4 was not statistically significant (P = .204). All other differences between any image of straight teeth and any image with misaligned teeth were significant and the smallest mean difference between the two groups of images was 1.87 (P = .039). However, in the images with aligned teeth, there was also a statistically significant difference with higher scores to the images with symmetrical nose in contrast with those with significant laterorhinia (mean difference = 1.03 cm). CONCLUSION: Teeth disharmonies had a more negative impact on the aesthetic perception of the face than did nose deviations, for both dentists and laypersons.