Hand response differences in a self-face identification task

'Magic cosmetic fillers': Appearance-enhancement effects on self-face recognition

People naturally exhibit a self-serving bias which can be observed in their tendency to judge their own physical attractiveness more favourably than that of others. Despite this positive self-perception, minimally invasive cosmetic injectable procedures for facial rejuvenation and enhancement are becoming increasingly common. It remains unclear, however, whether recognizing an altered version of one's own face, enhanced cosmetically, correlates with a positive view of cosmetic surgery and excessive preoccupations about physical characteristics perceived as defects (body dysmorphic concerns). In this study, 30 healthy female participants, aged 18-24 years (Mage = 21.1 years, SD = 1.6), engaged in a face recognition task during which their faces were digitally morphed with that of gender-matched unfamiliar women who had undergone cosmetic enhancements, specifically lip and cheek fillers. The duration of exposure to these modified faces varied with short (500 msec) and long (2000 msec) viewing periods. Participants were asked to identify whether the digital morphs represented themselves or the other woman. Self-reports regarding acceptance of cosmetic surgery and dysmorphic concerns were collected. Participants PSE indicated a tendency towards self-bias under short presentation times, shifting towards the other as presentation times lengthened. Interestingly, this effect was associated with greater acceptance of cosmetic surgery and higher body dysmorphic concerns. This study underscores the importance of understanding how perceptions of others' physical appearances can influence self-recognition and attitudes towards cosmetic surgery, which may have both positive and potentially harmful implications.

Laterality and hemispheric specialization of self-face recognition

Inspired by the pioneering work of Eran Zaidel beginning in the early 1970's on the role of the two cerebral hemispheres of the human brain in self-related cognition, we review research on self-face recognition from a laterality perspective. The self-face is an important proxy of the self, and self-face recognition has been used as an indicator of self-awareness more broadly. Over the last half century, behavioral and neurological data, along with over two decades of neuroimaging research evidence have accumulated on this topic, generally concluding a right-hemisphere dominance for self-face recognition. In this review, we briefly revisit the pioneering roots of this work by Sperry, Zaidel & Zaidel, and focus on the important body of neuroimaging literature on self-face recognition it has inspired. We conclude with a brief discussion of current models of self-related processing and future directions for research in this area.

The Self and Its Right Insula-Differential Topography and Dynamic of Right vs. Left Insula

Various studies demonstrate a special role of the right compared to the left anterior insula in mediating our self. However, the neural features of the right insula that allow for its special role remain unclear. Presupposing a spatiotemporal model of self—“Basis model of self-specificity” (BMSS)—we here address the following question: what spatial-topographic and temporal-dynamic features render neural activity in the right insula to be more suitable in mediating self-specificity than the left insula? First, applying fMRI, we demonstrate that the right insula (i) exhibits higher degrees of centrality in rest, and (ii) higher context-dependent functional connectivity in a self-specific task among regions of distinct layers of self (intero-, extero-proprioceptive, and mental). Second, using EEG in rest and task, we show that the right insula shows longer autocorrelation window (ACW) in its neural activity than both left insula and other regions of the different layers of self. Together, we demonstrate special topographic, i.e., high functional connectivity, and dynamic, i.e., long ACW, neural features of the right insula compared to both left insula and other regions of the distinct layers of self. This suits neural activity in the right insula ideally for high functional integration and temporal continuity as key features of the self including its intero-, extero-proprioceptive, and mental layers.

Self-other distinction and borderline personality disorder features: Evidence for egocentric and altercentric bias in a self-other facial morphing task

Self-other distinction (SOD) refers to the ability to distinguish one's own body, actions, and mental representations from those of others. Problems with SOD are considered to be a key feature of borderline personality disorder (BPD). However, empirical studies on SOD in BPD are scarce. Here, we present a study providing preliminary support for the usefulness and validity of a self-other facial morphing task to capture the capacity for SOD in a sample of nonclinical participants high (n = 30) and low (n = 32) in BPD features. Participants had to watch a video sequence in which their own face was gradually morphed into the face of an unfamiliar other (self-to-other) or vice versa (other-to-self), requiring them to indicate at which point they judged the morph to look more like the target face than the starting face. Consistent with predictions, results showed that participants in the high-BPD group judged the morph to look like themselves for longer in the self-to-other direction (suggestive of egocentric bias), but only with a relatively more attractive target face. In the other-to-self direction, the high-BPD group had more difficulty recognizing their own face (i.e., an altercentric bias), but this time only with the relatively less attractive face. Further research is needed to replicate these findings in clinical samples, but overall they suggest that the current task might be suited to investigate SOD problems in BPD. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

The role of impairments in self-other distinction in borderline personality disorder: A narrative review of recent evidence

Impairments in maintaining a differentiated sense of "self" and "other" are thought to be a central feature of borderline personality disorder (BPD). However, studies directly focusing on self-other distinction (SOD) in BPD are scarce, and these findings have not yet been integrated with novel insights into the neural mechanism involved in SOD. Here, we present a narrative review of recent behavioral and neuroimaging findings focusing on impairments in SOD in BPD. Behavioral findings of SOD at the embodied level provide preliminary evidence for impairments in multisensory integration in BPD. Furthermore, both behavioral and neuroscientific data converge to suggest that SOD impairments in BPD reflect an inability to shift between self and other representations according to task demands. Research also suggests that disruptions in infant-caregiver synchrony may play a role in the development of these impairments. Based on these findings, we present a new, integrative model linking impairments in SOD to reduced neural and behavioral synchrony in BPD. The implications of these findings for future research and clinical interventions are outlined.

Corticospinal Excitability during a Perspective Taking Task as Measured by TMS-Induced Motor Evoked Potentials

Only by understanding the ability to take a third-person perspective can we begin to elucidate the neural processes responsible for one’s inimitable conscious experience. The current study examined differences in hemispheric laterality during a first-person perspective (1PP) and third-person perspective (3PP) taking task, using transcranial magnetic stimulation (TMS). Participants were asked to take either the 1PP or 3PP when identifying the number of spheres in a virtual scene. During this task, single-pulse TMS was delivered to the motor cortex of both the left and right hemispheres of 10 healthy volunteers. Measures of TMS-induced motor-evoked potentials (MEPs) of the contralateral abductor pollicis brevis (APB) were employed as an indicator of lateralized cortical activation. The data suggest that the right hemisphere is more important in discriminating between 1PP and 3PP. These data add a novel method for determining perspective taking and add to the literature supporting the role of the right hemisphere in meta representation.

Time course of body recognition in women with weight and shape concerns assessed by steady-state visual evoked potentials (SSVEP)

This study aimed to examine self-body recognition in women with high (HWSC) and low weight and shape concerns (LWSC). Thus, the detection rate, the reaction time and the perceptual threshold for recognizing one's own body in a morphed body were measured in n = 25 women with HWSC and n = 26 women with LWSC. Furthermore, by using steady-state visual evoked potentials (SSVEPs), neuronal correlates of body recognition were recorded. The perceptual threshold for recognizing one's own body was higher for women with HWSC in the case of a morph with a thinner body. No group differences emerged for morphs with obese or average-weight bodies. The SSVEP amplitudes did not differentiate between one's own and another body in either group. The results suggest that for women with HWSC, their negative body schemata might hamper recognition of their own body in a thinner morph. Otherwise, self-body recognition is similar in women with LWSC and HWSC.

Prediction-based neural mechanisms for shielding the self from existential threat

The human mind has an automatic tendency to avoid awareness of its mortality. How this protective mechanism is implemented at the neuronal level is unknown. Here we test the hypothesis that prediction-based mechanisms mediate death-denial by shielding the self from existential threat. We provide evidence that self-specific predictive processes are downregulated during the perception of death-related linguistic stimuli and that this mechanism can predict fear-of-death. Using a magnetoencephalography visual mismatch paradigm, we show that the brain's automatic prediction response to deviancy is eliminated when death words and self-face representations are coupled, but remains present when coupled to other-face or to negative words. We further demonstrate a functional link between how death impacts self-image vs. Other-image, and show that it predicts fear-of-death. Finally, we confirm this effect in a behavioral active inference experiment showing that death-related words bias perceptual judgment on facial self and other morphed video clips. Together these results lay out, for the first time, a plausible neural-based mechanism of death-denial.

Brain Activity Related to the Judgment of Face-Likeness: Correlation between EEG and Face-Like Evaluation

Faces represent important information for social communication, because social information, such as face-color, expression, and gender, is obtained from faces. Therefore, individuals' tend to find faces unconsciously, even in objects. Why is face-likeness perceived in non-face objects? Previous event-related potential (ERP) studies showed that the P1 component (early visual processing), the N170 component (face detection), and the N250 component (personal detection) reflect the neural processing of faces. Inverted faces were reported to enhance the amplitude and delay the latency of P1 and N170. To investigate face-likeness processing in the brain, we explored the face-related components of the ERP through a face-like evaluation task using natural faces, cars, insects, and Arcimboldo paintings presented upright or inverted. We found a significant correlation between the inversion effect index and face-like scores in P1 in both hemispheres and in N170 in the right hemisphere. These results suggest that judgment of face-likeness occurs in a relatively early stage of face processing.

Self- or familiar-face recognition advantage? New insight using ambient images

Self-face recognition has been widely explored in the past few years. Nevertheless, the current literature relies on the use of standardized photographs which do not represent daily-life face recognition. Therefore, we aim for the first time to evaluate self-face processing in healthy individuals using natural/ambient images which contain variations in the environment and in the face itself. In total, 40 undergraduate and graduate students performed a forced delayed-matching task, including images of one's own face, friend, famous and unknown individuals. For both reaction time and accuracy, results showed that participants were faster and more accurate when matching different images of their own face compared to both famous and unfamiliar faces. Nevertheless, no significant differences were found between self-face and friend-face and between friend-face and famous-face. They were also faster and more accurate when matching friend and famous faces compared to unfamiliar faces. Our results suggest that faster and more accurate responses to self-face might be better explained by a familiarity effect - that is, (1) the result of frequent exposition to one's own image through mirror and photos, (2) a more robust mental representation of one's own face and (3) strong face recognition units as for other familiar faces.

Anodal transcranial direct current stimulation of right temporoparietal area inhibits self-recognition

Self–other discrimination is a crucial mechanism for social cognition. Neuroimaging and neurostimulation research has pointed to the involvement of the right temporoparietal region in a variety of self–other discrimination tasks. Although repetitive transcranial magnetic stimulation over the right temporoparietal area has been shown to disrupt self–other discrimination in face-recognition tasks, no research has investigated the effect of increasing the cortical excitability in this region on self–other face discrimination. Here we used transcranial direct current stimulation (tDCS) to investigate changes in self–other discrimination with a video-morphing task in which the participant’s face morphed into, or out of, a familiar other’s face. The task was performed before and after 20 min of tDCS targeting the right temporoparietal area (anodal, cathodal, or sham stimulation). Differences in task performance following stimulation were taken to indicate a change in self–other discrimination. Following anodal stimulation only, we observed a significant increase in the amount of self-face needed to distinguish between self and other. The findings are discussed in relation to the control of self and other representations and to domain-general theories of social cognition.

An Own-Age Bias in Recognizing Faces with Horizontal Information

Horizontal information, as a result of a selective filtering process, is essential in younger adults’ (YA) ability to recognize human faces. Obermeyer et al. (2012) recently reported impaired recognition of faces with horizontal information in older adults (OA) suggesting age-variant processing. Two yet unconsidered factors (stimulus age and exposure duration) that may have influenced previous results, were investigated in this study. Forty-seven YA (18–35 years) and 49 OA (62–83 years) were tested in a 2 × 2 × 2 × 2 mixed design with the between-subjects factors age group (YA vs. OA) and stimulus age (young faces vs. older faces) and the within-subjects factors filter [filtered (HF) faces vs. unfiltered faces (UF)] and exposure duration (0.8 s vs. 8 s). Subjects were presented morph videos between pairs of faces: a starting face gradually merged into either the previously encoded target face or a control face. As expected, results showed an increase in recognition sensitivity (d′) with longer exposure duration in YA with both younger and older HF faces. OA, however, were unable to recognize filtered young faces not even with increased exposure duration. Furthermore, only elderly participants showed more accurate recognition with faces of their own age relative to other-age faces (own-age bias, OAB). For YA no OAB was observed. Filtered face recognition was significantly correlated with unfiltered recognition in YA but not in OA. It is concluded, that processing of horizontal information changes at a higher age. Presenting filtered or unfiltered faces both targets convergent face-specific processing only in YA but not in OA.

Metaphorical mapping between raw-cooked food and strangeness-familiarity in Chinese culture

Previous research has demonstrated metaphorical mappings between physical coldness-warmth and social distance-closeness. Since the concepts of interpersonal warmth are frequently expressed in terms of food-related words in Chinese, the present study sought to explore whether the concept of raw-cooked food could be unconsciously and automatically mapped onto strangeness-familiarity. After rating the nutritive value of raw or cooked foods, participants were presented with morphing movies in which their acquaintances gradually transformed into strangers or strangers gradually morphed into acquaintances, and were asked to stop the movies when the combined images became predominantly target faces. The results demonstrated that unconscious and automatic metaphorical mappings between raw-cooked food and strangeness-familiarity exist. This study provides a foundation for testing whether Chinese people can think about interpersonal familiarity using mental representations of raw-cooked food and supports cognitive metaphor theory from a crosslinguistic perspective.

Processing of self-related kinematic information embedded in static handwritten characters

Handwritten characters are generated by our own motor actions, and previous studies have shown that the manner in which such characters are perceived and generated is related. However, the temporal course of the neural activation involved in the processing of self-related kinematic information embedded in static handwritten characters remains to be identified. We applied event-related potential (ERP) recording while participants judged whether handwritten characters were self- or non-self-generated. To test the effects of the self-related kinematic characteristics of static handwritten characters, we conducted two experiments in which the styles or familiarity of characters were manipulated. The ERP results indicated differences in brain activation between self- and non-self-written characters for the P250 component (250-350ms after stimulus onset) in right posterior regions and for the late positive component (LPC; 350-500ms after stimulus onset) in anterior midline regions; this was the case even when the handwritten characters were not generated in their usual form or were written for the first time. Therefore, our data indicate that self-information embedded in handwritten characters involves both right-lateralized brain activation associated with bodily self-processing and anterior midline brain activation related to self-referential processing.

Paying attention to my voice or yours: An ERP study with words

Self-related stimuli-such as one's own face or name-seem to be processed differently from non-self stimuli and to involve greater attentional resources, as indexed by larger amplitude of the P3 event-related potential (ERP) component. Nonetheless, the differential processing of self-related vs. non-self information using voice stimuli is still poorly understood. The present study investigated the electrophysiological correlates of processing self-generated vs. non-self voice stimuli, when they are in the focus of attention. ERP data were recorded from twenty right-handed healthy males during an oddball task comprising pre-recorded self-generated (SGV) and non-self (NSV) voice stimuli. Both voices were used as standard and deviant stimuli in distinct experimental blocks. SGV was found to elicit more negative N2 and more positive P3 in comparison with NSV. No association was found between ERP data and voice acoustic properties. These findings demonstrated an earlier and later attentional bias to self-generated relative to non-self voice stimuli. They suggest that one's own voice representation may have a greater affective salience than an unfamiliar voice, confirming the modulatory role of salience on P3.

Different neural processes accompany self-recognition in photographs across the lifespan: an ERP study using dizygotic twins

Our appearance changes over time, yet we can recognize ourselves in photographs from across the lifespan. Researchers have extensively studied self-recognition in photographs and have proposed that specific neural correlates are involved, but few studies have examined self-recognition using images from different periods of life. Here we compared ERP responses to photographs of participants when they were 5-15, 16-25, and 26-45 years old. We found marked differences between the responses to photographs from these time periods in terms of the neural markers generally assumed to reflect (i) the configural processing of faces (i.e., the N170), (ii) the matching of the currently perceived face to a representation already stored in memory (i.e., the P250), and (iii) the retrieval of information about the person being recognized (i.e., the N400). There was no uniform neural signature of visual self-recognition. To test whether there was anything specific to self-recognition in these brain responses, we also asked participants to identify photographs of their dizygotic twins taken from the same time periods. Critically, this allowed us to minimize the confounding effects of exposure, for it is likely that participants have been similarly exposed to each other's faces over the lifespan. The same pattern of neural response emerged with only one exception: the neural marker reflecting the retrieval of mnemonic information (N400) differed across the lifespan for self but not for twin. These results, as well as our novel approach using twins and photographs from across the lifespan, have wide-ranging consequences for the study of self-recognition and the nature of our personal identity through time.

Self-processing and the default mode network: interactions with the mirror neuron system

Recent evidence for the fractionation of the default mode network (DMN) into functionally distinguishable subdivisions with unique patterns of connectivity calls for a reconceptualization of the relationship between this network and self-referential processing. Advances in resting-state functional connectivity analyses are beginning to reveal increasingly complex patterns of organization within the key nodes of the DMN - medial prefrontal cortex and posterior cingulate cortex - as well as between these nodes and other brain systems. Here we review recent examinations of the relationships between the DMN and various aspects of self-relevant and social-cognitive processing in light of emerging evidence for heterogeneity within this network. Drawing from a rapidly evolving social-cognitive neuroscience literature, we propose that embodied simulation and mentalizing are processes which allow us to gain insight into another's physical and mental state by providing privileged access to our own physical and mental states. Embodiment implies that the same neural systems are engaged for self- and other-understanding through a simulation mechanism, while mentalizing refers to the use of high-level conceptual information to make inferences about the mental states of self and others. These mechanisms work together to provide a coherent representation of the self and by extension, of others. Nodes of the DMN selectively interact with brain systems for embodiment and mentalizing, including the mirror neuron system, to produce appropriate mappings in the service of social-cognitive demands.

The free-energy self: a predictive coding account of self-recognition

Recognising and representing one's self as distinct from others is a fundamental component of self-awareness. However, current theories of self-recognition are not embedded within global theories of cortical function and therefore fail to provide a compelling explanation of how the self is processed. We present a theoretical account of the neural and computational basis of self-recognition that is embedded within the free-energy account of cortical function. In this account one's body is processed in a Bayesian manner as the most likely to be "me". Such probabilistic representation arises through the integration of information from hierarchically organised unimodal systems in higher-level multimodal areas. This information takes the form of bottom-up "surprise" signals from unimodal sensory systems that are explained away by top-down processes that minimise the level of surprise across the brain. We present evidence that this theoretical perspective may account for the findings of psychological and neuroimaging investigations into self-recognition and particularly evidence that representations of the self are malleable, rather than fixed as previous accounts of self-recognition might suggest.

Shared or separate mechanisms for self-face and other-face processing? Evidence from adaptation

Evidence that self-face recognition is dissociable from general face recognition has important implications both for models of social cognition and for our understanding of face recognition. In two studies, we examine how adaptation affects the perception of personally familiar faces, and we use a visual adaptation paradigm to investigate whether the neural mechanisms underlying the recognition of one’s own and other faces are shared or separate. In Study 1 we show that the representation of personally familiar faces is rapidly updated by visual experience with unfamiliar faces, so that the perception of one’s own face and a friend’s face is altered by a brief period of adaptation to distorted unfamiliar faces. In Study 2, participants adapted to images of their own and a friend’s face distorted in opposite directions; the contingent aftereffects we observe are indicative of separate neural populations, but we suggest that these reflect coding of facial identity rather than of the categories “self” and “other.”

A left-hand superiority for the implicit detection of a rule

We set out to test the hypothesis of right-hemisphere superiority for the implicit detection of a rule. Forty healthy men provided speeded manual responses to randomly presented digits from 1 to 6 (left hand to 1-3, right hand to 4-6). Red digits on trial n signaled that the response on trial n+1 should be made with one hand, blue digits with the other hand. White digits gave no signal (control trials). Half the participants were told that the stimulus color conveyed a rule that could be exploited to improve performance, the other half were not. After completing the first run, participants' awareness of the presence and nature of the rule was assessed and all were debriefed. Participants then performed a second run with identical stimulus conditions. In Run 1, none of the participants reported being aware of the nature of the rule. Reaction times (RTs) were longer after signal than no-signal trials, but only for the left hand. Participants informed about the presence of a rule tended to have longer RTs, irrespective of hand. In Run 2, RTs were shorter after signal than no-signal trials, and there were no differences between hands. The observed RT effect for the left-hand points to a right-hemisphere superiority for the detection and application of a rule in the absence of verbal awareness. Longer (instead of shorter) RTs in the signal trials are discussed in the framework of interhemispheric inhibition.

Functional dissociation of the left and right fusiform gyrus in self-face recognition

It is well known that the fusiform gyrus is engaged in face perception, such as the processes of face familiarity and identity. However, the functional role of the fusiform gyrus in face processing related to high-level social cognition remains unclear. The current study assessed the functional role of individually defined fusiform face area (FFA) in the processing of self-face physical properties and self-face identity. We used functional magnetic resonance imaging to monitor neural responses to rapidly presented face stimuli drawn from morph continua between self-face (Morph 100%) and a gender-matched friend's face (Morph 0%) in a face recognition task. Contrasting Morph 100% versus Morph 60% that differed in self-face physical properties but were both recognized as the self uncovered neural activity sensitive to self-face physical properties in the left FFA. Contrasting Morphs 50% that were recognized as the self versus a friend on different trials revealed neural modulations associated with self-face identity in the right FFA. Moreover, the right FFA activity correlated with the frequency of recognizing Morphs 50% as the self. Our results provide evidence for functional dissociations of the left and right FFAs in the representations of self-face physical properties and self-face identity.

Self-face recognition in children with autism spectrum disorders: a near-infrared spectroscopy study

It is assumed that children with autism spectrum disorders (ASD) have specificities for self-face recognition, which is known to be a basic cognitive ability for social development. In the present study, we investigated neurological substrates and potentially influential factors for self-face recognition of ASD patients using near-infrared spectroscopy (NIRS). The subjects were 11 healthy adult men, 13 normally developing boys, and 10 boys with ASD. Their hemodynamic activities in the frontal area and their scanning strategies (eye-movement) were examined during self-face recognition. Other factors such as ASD severities and self-consciousness were also evaluated by parents and patients, respectively. Oxygenated hemoglobin levels were higher in the regions corresponding to the right inferior frontal gyrus than in those corresponding to the left inferior frontal gyrus. In two groups of children these activities reflected ASD severities, such that the more serious ASD characteristics corresponded with lower activity levels. Moreover, higher levels of public self-consciousness intensified the activities, which were not influenced by the scanning strategies. These findings suggest that dysfunction in the right inferior frontal gyrus areas responsible for self-face recognition is one of the crucial neural substrates underlying ASD characteristics, which could potentially be used to evaluate psychological aspects such as public self-consciousness.

Who's afraid of the boss: cultural differences in social hierarchies modulate self-face recognition in Chinese and Americans

Human adults typically respond faster to their own face than to the faces of others. However, in Chinese participants, this self-face advantage is lost in the presence of one's supervisor, and they respond faster to their supervisor's face than to their own. While this "boss effect" suggests a strong modulation of self-processing in the presence of influential social superiors, the current study examined whether this effect was true across cultures. Given the wealth of literature on cultural differences between collectivist, interdependent versus individualistic, independent self-construals, we hypothesized that the boss effect might be weaker in independent than interdependent cultures. Twenty European American college students were asked to identify orientations of their own face or their supervisors' face. We found that European Americans, unlike Chinese participants, did not show a "boss effect" and maintained the self-face advantage even in the presence of their supervisor's face. Interestingly, however, their self-face advantage decreased as their ratings of their boss's perceived social status increased, suggesting that self-processing in Americans is influenced more by one's social status than by one's hierarchical position as a social superior. In addition, when their boss's face was presented with a labmate's face, American participants responded faster to the boss's face, indicating that the boss may represent general social dominance rather than a direct negative threat to oneself, in more independent cultures. Altogether, these results demonstrate a strong cultural modulation of self-processing in social contexts and suggest that the very concept of social positions, such as a boss, may hold markedly different meanings to the self across Western and East Asian cultures.

Neural markers of opposite-sex bias in face processing

Some behavioral and neuroimaging studies suggest that adults prefer to view attractive faces of the opposite sex more than attractive faces of the same sex. However, unlike the other-race face effect (Caldara et al., 2004), little is known regarding the existence of an opposite-/same-sex bias in face processing. In this study, the faces of 130 attractive male and female adults were foveally presented to 40 heterosexual university students (20 men and 20 women) who were engaged in a secondary perceptual task (landscape detection). The automatic processing of face gender was investigated by recording ERPs from 128 scalp sites. Neural markers of opposite- vs. same-sex bias in face processing included larger and earlier centro-parietal N400s in response to faces of the opposite sex and a larger late positivity (LP) to same-sex faces. Analysis of intra-cortical neural generators (swLORETA) showed that facial processing-related (FG, BA37, BA20/21) and emotion-related brain areas (the right parahippocampal gyrus, BA35; uncus, BA36/38; and the cingulate gyrus, BA24) had higher activations in response to opposite- than same-sex faces. The results of this analysis, along with data obtained from ERP recordings, support the hypothesis that both genders process opposite-sex faces differently than same-sex faces. The data also suggest a hemispheric asymmetry in the processing of opposite-/same-sex faces, with the right hemisphere involved in processing same-sex faces and the left hemisphere involved in processing faces of the opposite sex. The data support previous literature suggesting a right lateralization for the representation of self-image and body awareness.

The neural correlates of visual self-recognition

This paper presents a review of studies that were aimed at determining which brain regions are recruited during visual self-recognition, with a particular focus on self-face recognition. A complex bilateral network, involving frontal, parietal and occipital areas, appears to be associated with self-face recognition, with a particularly high implication of the right hemisphere. Results indicate that it remains difficult to determine which specific cognitive operation is reflected by each recruited brain area, in part due to the variability of used control stimuli and experimental tasks. A synthesis of the interpretations provided by previous studies is presented. The relevance of using self-recognition as an indicator of self-awareness is discussed. We argue that a major aim of future research in the field should be to identify more clearly the cognitive operations induced by the perception of the self-face, and search for dissociations between neural correlates and cognitive components.

Lateralization of kin recognition signals in the human face

When human subjects view photographs of faces, their judgments of identity, gender, emotion, age, and attractiveness depend more on one side of the face than the other. We report an experiment testing whether allocentric kin recognition (the ability to judge the degree of kinship between individuals other than the observer) is also lateralized. One hundred and twenty-four observers judged whether or not pairs of children were biological siblings by looking at photographs of their faces. In three separate conditions, (1) the right hemi-face was masked, (2) the left hemi-face was masked, or (3) the face was fully visible. The d' measures for the masked left hemi-face and masked right hemi-face were 1.024 and 1.004, respectively (no significant difference), and the d' measure for the unmasked face was 1.079, not significantly greater than that for either of the masked conditions. We conclude, first, that there is no superiority of one or the other side of the observed face in kin recognition, second, that the information present in the left and right hemi-faces relevant to recognizing kin is completely redundant, and last that symmetry cues are not used for kin recognition.

rTMS to the right inferior parietal lobule disrupts self-other discrimination

Self-other discrimination is fundamental to social interaction, however, little is known about the neural systems underlying this ability. In a previous functional magnetic resonance imaging study, we demonstrated that a right fronto-parietal network is activated during viewing of self-faces as compared with the faces of familiar others. Here we used image-guided repetitive transcranial magnetic stimulation (rTMS) to create a 'virtual lesion' over the parietal component of this network to test whether this region is necessary for discriminating self-faces from other familiar faces. The current results indeed show that 1 Hz rTMS to the right inferior parietal lobule (IPL) selectively disrupts performance on a self-other discrimination task. Applying 1 Hz rTMS to the left IPL had no effect. It appears that activity in the right IPL is essential to the task, thus providing for the first time evidence for a causal relation between a human brain area and this high-level cognitive capacity.

Scanning strategies do not modulate face identification: eye-tracking and near-infrared spectroscopy study

BACKGROUND

During face identification in humans, facial information is sampled (seeing) and handled (processing) in ways that are influenced by the kind of facial image type, such as a self-image or an image of another face. However, the relationship between seeing and information processing is seldom considered. In this study, we aimed to reveal this relationship using simultaneous eye-tracking measurements and near-infrared spectroscopy (NIRS) in face identification tasks.

METHODOLOGY/PRINCIPAL FINDINGS

22 healthy adult subjects (8 males and 14 females) were shown facial morphing movies in which an initial facial image gradually changed into another facial image (that is, the subject's own face was changed to a familiar face). The fixation patterns on facial features were recorded, along with changes in oxyhemoglobin (oxyHb) levels in the frontal lobe, while the subjects identified several faces. In the self-face condition (self-face as the initial image), hemodynamic activity around the right inferior frontal gyrus (IFG) was significantly greater than in the familiar-face condition. On the other hand, the scanning strategy was similar in almost all conditions with more fixations on the eyes and nose than on other areas. Fixation time on the eye area did not correlate with changes in oxyHb levels, and none of the scanning strategy indices could estimate the hemodynamic changes.

CONCLUSIONS/SIGNIFICANCE

We conclude that hemodynamic activity, i.e., the means of processing facial information, is not always modulated by the face-scanning strategy, i.e., the way of seeing, and that the right IFG plays important roles in both self-other facial discrimination and self-evaluation.

Looking for myself: current multisensory input alters self-face recognition

How do I know the person I see in the mirror is really me? Is it because I know the person simply looks like me, or is it because the mirror reflection moves when I move, and I see it being touched when I feel touch myself? Studies of face-recognition suggest that visual recognition of stored visual features inform self-face recognition. In contrast, body-recognition studies conclude that multisensory integration is the main cue to selfhood. The present study investigates for the first time the specific contribution of current multisensory input for self-face recognition. Participants were stroked on their face while they were looking at a morphed face being touched in synchrony or asynchrony. Before and after the visuo-tactile stimulation participants performed a self-recognition task. The results show that multisensory signals have a significant effect on self-face recognition. Synchronous tactile stimulation while watching another person's face being similarly touched produced a bias in recognizing one's own face, in the direction of the other person included in the representation of one's own face. Multisensory integration can update cognitive representations of one's body, such as the sense of ownership. The present study extends this converging evidence by showing that the correlation of synchronous multisensory signals also updates the representation of one's face. The face is a key feature of our identity, but at the same time is a source of rich multisensory experiences used to maintain or update self-representations.

Objective metamemory testing captures awareness of deficit in Alzheimer's disease

For reasons that remain unknown, there is marked inter-person variability in awareness of episodic memory loss in patients with Alzheimer's disease (AD). Existing research designs, primarily subjective in nature, have been at a relative disadvantage for evaluating disordered metamemory and its relation to the clinical and neuropathological heterogeneity of AD, as well as its prognosis for various disease outcomes. The current study sought to establish an objective means of evaluating metamemory in AD by modifying traditional metacognitive paradigms in which participants are asked to make predictions regarding their own memory performance. Variables derived from this measure were analyzed in relation to clinically rated awareness for memory loss. As predicted, a range of awareness levels existed across patients with mild to moderate AD (n=24) and clinical ratings of awareness (CRA) were significantly associated with verbal episodic memory monitoring (r = .46, p = .03). Further, patients who were rated as aware of their memory loss remained well calibrated over the course of the task whereas those rated as relatively unaware grew over-confident in their predictions [F (1, 33) = 4.19, p = .02]. Findings suggest that over-confidence may be related to impaired online error recognition and compromised use of metamemory strategies such as the Memory for Past Test (MPT) heuristic. Importantly, clinically rated awareness did not vary as a function of demographic variables, global cognition, or verbal memory. However, participants characterized as relatively unaware were impaired on a nonverbal memory task as compared to aware participants [F (1, 20) = 6.98, p = .02]. The current study provides preliminary support for the use of a recognition-based verbal episodic memory monitoring task as a quantitative measure of awareness for memory loss in AD, and offers insight into the manner in which metamemory breaks down. Discrepancies in nonverbal memory across the two awareness groups provide preliminary support for the idea that metamemory variability in AD may be related to the neuroanatomic presentation of the disease, with disordered awareness potentially reflective of a critical level of right hemisphere involvement.

Self-face recognition in schizophrenia

OBJECTIVE

Altered self-awareness might be a core feature of schizophrenia. Facial self-recognition in children and non-human primates has been linked to the emergence of self-awareness. In this study, the ability to recognize the own face as an indicator of certain aspects of self-awareness was investigated in patients with schizophrenia.

METHODS

Standardized facial pictures of the participants (20 patients with DSM-IV schizophrenia and 20 healthy controls), of close same-sex relatives of the participants and of unknown persons were taken. These stimuli were presented on a computer screen serially in three forced choice identity recognition experiments: facial identities were presented (I) for 5 s centrally on the screen; (II) in the participants' left and right visual hemifields for 100 ms; (III) as morphed blendings between the identities, centrally for 5 s.

RESULTS

There was no interaction between group and facial identity in experiments I and III. However, in experiment II an interaction between hemifield and identity emerged in the patients (p=.002). They exhibited higher error rates for their own face presented to the right hemifield (p=.003), whereas there was no effect for the control subjects. Additionally, self-face recognition (reaction time in experiment I; p=.0009 and error rates in II; p=.0006) was related to hallucinations in the patients.

CONCLUSIONS

These results support the notion of a specific self-face processing dysfunction in schizophrenia. This might be related to altered self-awareness in schizophrenia.

Visual self-recognition in patients with schizophrenia

Self-processing is associated with distinct patterns of behavior and neural activity in healthy individuals. Self-monitoring deficits have been reported in schizophrenia in auditory and tactile modalities but it is unknown whether they generalize to all sensory domains. We investigated self-face recognition in patients with schizophrenia, using a visual search paradigm with three types of targets: objects, famous faces and self-faces. Schizophrenic patients showed increased reaction time (RT) for detecting targets overall compared to normal controls but they showed faster RT for self-face compared with the Famous-face condition. For healthy controls, there was no difference between Self- and Famous-face conditions. Thus, visual search for self-face is more efficient than for famous faces and self-face recognition is spared in schizophrenia. These findings suggest that impaired self-processing in schizophrenia may be task-dependent rather than ubiquitous.

Here I am: The cortical correlates of visual self-recognition

Recently, interest in the neural correlates of self-recognition has grown. Most studies concentrate on self-face recognition. However, there is a lack of convergence as to precise neuroanatomical locations underlying self-face recognition. In addition, recognition of familiar persons from bodies has been relatively neglected. In the present study, cerebral activity while participants performed a task in which they had to indicate the real appearance of themselves and of a gender-matched close colleague among intact and altered pictures of faces and bodies was measured. The right frontal cortex and the insula were found to be the main regions specifically implicated in visual self-recognition compared with visual processing of other highly familiar persons. Moreover, the right anterior insula along with the right anterior cingulate seemed to play a role in the integration of information about oneself independently of the stimulus domain. The processing of self-related pictures was also compared to scrambled versions of these pictures. Results showed that different areas of the occipito-temporal cortex were more or less recruited depending on whether a face or a body was perceived, as it has already been reported by several recent studies. The implication of present findings for a general framework of person identification is discussed.

An ERP study on self-relevant object recognition

We performed an event-related potential study to investigate the self-relevance effect in object recognition. Three stimulus categories were prepared: SELF (participant's own objects), FAMILIAR (disposable and public objects, defined as objects with less-self-relevant familiarity), and UNFAMILIAR (others' objects). The participants' task was to watch the stimuli passively. Results showed that left-lateralized N250 activity differentiated SELF and FAMILIAR from UNFAMILIAR, but SELF and FAMILIAR were not differentiated. In the later time-course, SELF was dissociated from FAMILIAR, indicating the self-relevance effect in object recognition at this stage. This activity did not show consistent lateralization, in contrast to previous studies reporting right lateralization in self-relevant face and name recognition. We concluded that in object recognition, self-relevance was processed by higher-order cognitive functions later than 300ms after stimulus onset.