Through the eyes of the own-race bias: eye-tracking and pupillometry during face recognition

Agent-Object Relationships in Level-2 Visual Perspective Taking: An Eye-Tracking Study

Visual perspective taking (VPT) generates a shared frame of reference for understanding how the world appears to others. Whilst greater cognitive and neurophysiological demands are associated with increasing angular distance between the self and other is well documented, accompanying attentional characteristics are not currently understood. Furthermore, although age and group status have been shown to impact task performance, other important cues, such as the relationship between agents and objects, have not been manipulated. Therefore, 35 university students participated in an eye-tracking experiment where they completed a VPT task with agents positioned at a low or high angular disparity (45° or 135° respectively). The congruence between the age of the agent (child vs adult) and the object they are attending to (e.g., teddy-bear vs kettle) was also manipulated. Participants were required to respond to the direction of the object from the agent's position. The findings reveal more fixations and increased dwell-times on agents compared to objects, but this was moderated by the age of the task agent. Results also showed more attentional transitions between agents and objects at higher angular disparities. These results converge with behavioural and neurophysiological descriptions of task performance in previous studies. Furthermore, the congruency of the relationship between agents and objects also impacted attention shifting and response times, highlighting the importance of understanding how social cues and contexts can modulate VPT processes in everyday contexts and social interaction.

The effect of social factors on eye movements made when judging the aesthetic merit of figurative paintings

In the present study we explore how social factors (group contact, individuating experience, implicit racial bias) influence the eye movements made during the visual exploration when judging their aesthetic merit of figurative paintings depicting White and Black sitters. An opportunity sample of participants visiting a gallery in Liverpool viewed ten artworks while their eye movements were recorded and completed a set of individual difference measures. The individual difference measures indicated self-report of art interest, social contact and individuating experience with both Black and White communities, and implicitly held racial bias. The results showed that, despite viewing the paintings for less time, the majority of participants reported paintings showing Black sitters as more interesting, emotionally moving, and pleasurable then those depicting White sitters. However, if a participant reported limited social contact with Black community, and a negative implicit racial bias against them, their rating of aesthetic merit of paintings showing Black sitters was reduced, viewing time increased, and fixations became more focused on faces. The influence of social factors on the viewing of paintings showing White sitters was limited to aesthetic rating. The results are discussed in terms of how social factors influence eye movements when viewing paintings in a real-world setting.

Different features for different races: Tracking the eyes of Asian, Black, and White participants viewing Asian, Black, and White Faces

The own-race bias (ORB) is an effect in which humans remember faces from their own race better than faces from another race. Where people look when processing faces of different races plays a role in this effect, but the exact relationship between looking and the ORB is debated. One perspective is that the same facial features are important for memory for faces of all races and the ORB emerges when people look longer at the useful features for own- than other-race faces. Another perspective is that different facial features are useful for faces of different races and the ORB emerges when people look longer at features that are useful for their own race than at features that are useful for other-race faces. The present study aimed to discriminate these perspectives by examining looking patterns in Asian, Black, and White participants while they learned and later recognized Asian, Black, and White faces. Regardless of their race, participants looked at different facial features depending on the race of the face. In addition, different features were useful for memory depending on the race of the face. As such, results are in line with the perspective that different facial features are useful for different race faces.

Examining the Contribution of Physical Cues for Same- and Cross-Race Face Individuation

Face individuation involves sensitivity to physical characteristics that provide information about identity. We examined whether Black and White American faces differ in terms of individuating information, and whether Black and White perceivers differentially weight information when judging same-race and cross-race faces. Study 1 analyzed 20 structural metrics (e.g., eye width, nose length) of 158 Black and White faces to determine which differentiate faces within each group. High-utility metrics (e.g., nose length, eye height, chin length) differentiated faces of both groups, low-utility metrics (e.g., face width, eye width, face length) offered less individuating information. Study 2 (N = 4,510) explored Black and White participants' sensitivity to variation on structural metrics using similarity ratings. High-utility metrics affected perceived dissimilarity more than low-utility metrics. This relationship was non-significantly stronger for same-race faces rather than cross-race faces. Perceivers also relied more on features that were racially stereotypic of the faces they were rating.

Face race and sex impact visual fixation strategies for upright and inverted faces in 3- to 6-year-old children

Everyday face experience tends to be biased, such that infants and young children interact more often with own-race and female faces leading to differential processing of faces within these groups relative to others. In the present study, visual fixation strategies were recorded using eye tracking to determine the extent to which face race and sex/gender impact a key index of face processing in 3- to 6-year-old children (n = 47). Children viewed male and female upright and inverted White and Asian faces while visual fixations were recorded. Face orientation was found to have robust effects on children's visual fixations, such that children exhibited shorter first fixation and average fixation durations and a greater number of fixations for inverted compared to upright face trials. First fixations to the eye region were also greater for upright compared to inverted faces. Fewer fixations and longer duration fixations were found for trials with male compared to female faces and for upright compared to inverted unfamiliar-race faces, but not familiar-race faces. These findings demonstrate evidence of differential fixation strategies toward different types of faces in 3- to 6-year-old children, illustrating the importance of experience in the development of visual attention to faces.

The impact of social motivation on the other-race effect under high and low social status

The other-race effect refers to the phenomenon in which the chance of individuals misidentifying faces from other races more than their own race is significantly higher. This study explored the effect of motivation on the other-race effect by manipulating the social status of faces. The results showed that: (1) compared to other-race faces with low social status, when individuals' perceptions of the social status of other-race faces increased, individuals' recognition scores for high social status other-race faces increased, and the other-race effect disappeared, and (2) when individuals' perceptions of the social status of other-race faces decreased, there was no significant difference in individuals' recognition scores of other-race faces, of either high or low social status. These findings suggest that motivation has a significant impact on the other-race effect.

Registered report: Social face evaluation: ethnicity-specific differences in the judgement of trustworthiness of faces and facial parts

Social face evaluation is a common and consequential element of everyday life based on the judgement of trustworthiness. However, the particular facial regions that guide such trustworthiness judgements are largely unknown. It is also unclear whether different facial regions are consistently utilized to guide judgments for different ethnic groups, and whether previous exposure to specific ethnicities in one's social environment has an influence on trustworthiness judgements made from faces or facial regions. This registered report addressed these questions through a global online survey study that recruited Asian, Black, Latino, and White raters (N = 4580). Raters were shown full faces and specific parts of the face for an ethnically diverse, sex-balanced set of 32 targets and rated targets' trustworthiness. Multilevel modelling showed that in forming trustworthiness judgements, raters relied most strongly on the eyes (with no substantial information loss vis-à-vis full faces). Corroborating ingroup-outgroup effects, raters rated faces and facial parts of targets with whom they shared their ethnicity, sex, or eye color as significantly more trustworthy. Exposure to ethnic groups in raters' social environment predicted trustworthiness ratings of other ethnic groups in nuanced ways. That is, raters from the ambient ethnic majority provided slightly higher trustworthiness ratings for stimuli of their own ethnicity compared to minority ethnicities. In contrast, raters from an ambient ethnic minority (e.g., immigrants) provided substantially lower trustworthiness ratings for stimuli of the ethnic majority. Taken together, the current study provides a new window into the psychological processes underlying social face evaluation and its cultural generalizability. PROTOCOL REGISTRATION: The stage 1 protocol for this Registered Report was accepted in principle on 7 January 2022. The protocol, as accepted by the journal, can be found at: https://doi.org/10.6084/m9.figshare.18319244 .

Normal gaze processing in developmental prosopagnosia

Two key functions in human face perception are gaze discrimination and identity recognition. Here we examine whether gaze discrimination can be intact when identity recognition is impaired in developmental prosopagnosia (DP). We ran a large sample of developmental prosopagnosics (DPs) with a series of gaze discrimination tasks that assess various mechanisms in gaze processing. Experiment 1 (N = 101 DP participants) investigates spatial processing using an abnormal eye gaze detection task and a Wollaston illusion task that measures perceptual integration of eye and head direction. Experiment 2 (N = 45 DP participants) investigates temporal processing using an adaptation task and a serial dependence task. Despite their deficits with identity recognition, DPs performed in the normal range across both experiments. These results demonstrate that gaze discrimination can be normal in DP, and that various mechanisms of gaze processing can be spared when identity recognition is impaired. Our findings clarify the highly selective nature of impairments in DP and provide support for neurocognitive models of face perception with distinct mechanisms for gaze and identity processing.

Perceiving ingroup and outgroup faces within and across nations

The human face is arguably the most important of all social stimuli because it provides so much valuable information about others. Therefore, one critical factor for successful social communication is the ability to process faces. In general, a wide body of social cognitive research has demonstrated that perceivers are better at extracting information from their own-race compared to other-race faces and that these differences can be a barrier to positive cross-race relationships. The primary objective of the present paper was to provide an overview of how people process faces in diverse contexts, focusing on racial ingroup and outgroup members within one nation and across nations. To achieve this goal, we first broadly describe social cognitive research on categorization processes related to ingroups vs. outgroups. Next, we briefly examine two prominent mechanisms (experience and motivation) that have been used to explain differences in recognizing facial identities and identifying emotions when processing ingroup and outgroup racial faces within nations. Then, we explore research in this domain across nations and cultural explanations, such as norms and practices, that supplement the two proposed mechanisms. Finally, we propose future cross-cultural research that has the potential to help us better understand the role of these key mechanisms in processing ingroup and outgroup faces.

Accepting Human-like Avatars in Social and Professional Roles

Humans report perceptions of unease or eeriness as humanoid/android robots and digital avatars approach human-like physical resemblance, a phenomenon alluded by the Uncanny Valley theory. This study extends the discussions on interactions and acceptance of digital avatars with findings from three experiments. In the first, perceptive evaluation of actors in clips from computer-generated animation and a live-action version of the same movie was examined. In the second experiment, we considered short clips with highly realistic digital avatars to measure recognition ability, the extent of eeriness, and specific physical features identified as unreal. The fixation area and pupil size variation recorded using an eye tracker were analyzed to infer attention to the body, face, and emotional response, respectively. Building on these findings, the third experiment looked at acceptance in roles requiring human skill, empathy, and cognitive ability. The results show that based on perceptions from physical attributes, the eeriness scores diverge from the uncanny valley theory as human-likeness increases. The realistic CGI and mocap technology could have helped cross the valley. Visual attention inferred from gaze behavior was similar for live-action and CGI. At the same time, we observe pupil size changes reflecting emotions like eeriness when the avatars either talked or smiled. Proficiency and acceptance scores were lower for roles requiring complex social cognition processes, such as friends and judicial decision-making. Interestingly, real-life stereotypes of gender roles were transferred to digital avatars too. The findings suggest an ambiguity in accepting human-like avatars in social and professional interactions, emphasizing the need for a multi-dimensional approach when applying the uncanny valley theory. A detailed and contextual examination is imperative as technological advancements have placed humans closer to co-existing with digital or physical android/humanoid robots.

Impact of perceived interpersonal similarity on attention to the eyes of same-race and other-race faces

One reason for the persistence of racial discrimination may be anticipated dissimilarity with racial outgroup members that prevent meaningful interactions. In the present research, we investigated whether perceived similarity would impact the processing of same-race and other-race faces. Specifically, in two experiments, we varied the extent to which White participants were ostensibly similar to targets via bogus feedback on a personality test. With an eye tracker, we measured the effect of this manipulation on attention to the eyes, a critical region for person perception and face memory. In Experiment 1, we monitored the impact of perceived interpersonal similarity on White participants’ attention to the eyes of same-race White targets. In Experiment 2, we replicated this procedure, but White participants were presented with either same-race White targets or other-race Black targets in a between-subjects design. The pattern of results in both experiments indicated a positive linear effect of similarity—greater perceived similarity between participants and targets predicted more attention to the eyes of White and Black faces. The implications of these findings related to top-down effects of perceived similarity for our understanding of basic processes in face perception, as well as intergroup relations, are discussed.

The effect of implicit racial bias on recognition of other-race faces

Previous research has established a possible link between recognition performance, individuation experience, and implicit racial bias of other-race faces. However, it remains unclear how implicit racial bias might influence other-race face processing in observers with relatively extensive experience with the other race. Here we examined how recognition of other-race faces might be modulated by observers’ implicit racial bias, in addition to the effects of experience and face recognition ability. Caucasian participants in a culturally diverse city completed a memory task for Asian and Caucasian faces, an implicit association test, a questionnaire assessing experience with Asians and Caucasians, and a face recognition ability test. As expected, recognition performance for Asian faces was positively predicted by increased face recognition ability, and experience with Asians. More importantly, it was also negatively predicted by increased positive bias towards Asians, which was modulated by an interaction between face recognition ability and implicit bias, with the effect of implicit bias observed predominantly in observers with high face recognition ability. Moreover, the positions of the first two fixations when participants learned the other-race faces were affected by different factors, with the first fixation modulated by the effect of experience and the second fixation modulated by the interaction between implicit bias and face recognition ability. Taken together, these findings suggest the complexity in understanding the perceptual and socio-cognitive influences on the other-race effect, and that observers with high face recognition ability may more likely evaluate racial features involuntarily when recognizing other-race faces.

Interaction Between Conscious and Unconscious Information-Processing of Faces and Words

It is widely acknowledged that holistic processing is a key characteristic of face perception. Although holistic processing implies the automatic integration of face parts, it is unclear whether such processing requires the awareness of face parts. Here, we investigated the interactions between visible face parts and face parts rendered invisible using continuous flash suppression (CFS). In the first experiment with the upper half-face visible and the lower half-face invisible, the results showed that perceived face identity was influenced by the invisible lower half-face, suggesting that integration occurs between the visible and invisible face parts, a variant of the "composite face effect". In the second experiment, we investigated the influence of visible face parts on the processing of invisible face parts, as measured by the time it took for the invisible parts to break out from CFS. The results showed a visible-to-invisible facilitation effect, that the aligned invisible face parts broke through CFS faster than when the visible and invisible face parts were misaligned. Visible eyes had a stronger influence on the invisible nose/mouth than the other way around. Such facilitation of processing from visible to invisible parts was also found when Chinese characters were used as stimuli. These results show that information integration occurs across the consciousness boundary.

(Eye-) Tracking the Other-Race Effect: Comparison of Eye Movements During Encoding and Recognition of Ingroup Faces With Proximal and Distant Outgroup Faces

People experience difficulties recognizing faces of ethnic outgroups, known as the other-race effect. The present eye-tracking study investigates if this effect is related to differences in visual attention to ingroup and outgroup faces. We measured gaze fixations to specific facial features and overall eye-movement activity level during an old/new recognition task comparing ingroup faces with proximal and distal ethnic outgroup faces. Recognition was best for ingroup faces and decreased gradually for proximal and distal outgroup faces. Participants attended more to the eyes of ingroup faces than outgroup faces, but this effect was unrelated to recognition performance. Ingroup-outgroup differences in eye-movement activity level did not emerge during the study phase, but during the recognition phase, with ingroup-outgroup differences varying as a function of recognition accuracy and old/new effects. Overall, ingroup-outgroup effects on recognition performance and eye movements were more pronounced for recognition of new items, emphasizing the role of retrieval processes.

Truth and lies in your eyes: Pupil dilation of White participants in truthful and deceptive responses to White and Black partners

In the present study, we examined the pupillary response of White participants who were asked to tell the truth or lie to White or Black partners. Research on cues to deception has assumed that lying is more cognitively demanding that truth telling. In line with this assumption, previous studies have shown that lying is associated with greater pupil dilation, a behavioral cue that typically manifests itself under conditions of stress or cognitive effort. In accordance with these results, we predicted greater pupil dilation when lying than when telling the truth. Furthermore, pupil dilation was expected to be greater when responding to White than Black partners. Finally, we hypothesized that pupil dilation would be greater when lying to White than Black partners. Participants were instructed to answer a set of questions, half truthfully and half deceptively. They were led to believe that White vs. Black partners (one male and one female) would ask the questions via computer connection. Indeed, we used feminine and masculine synthetic voices. Pupil dilation was assessed with a remote eye-tracking system. Results provided support for the first two hypotheses. However, the predicted interaction between race of partners and truth status of message (lying vs. telling the truth) was nonsignificant. Our findings highlight the importance of considering race in the study of truthful and deceptive communications.

Infants' Gaze Patterns for Same-Race and Other-Race Faces, and the Other-Race Effect

The other-race effect (ORE) can be described as difficulties in discriminating between faces of ethnicities other than one's own, and can already be observed at approximately 9 months of age. Recent studies also showed that infants visually explore same-and other-race faces differently. However, it is still unclear whether infants' looking behavior for same- and other-race faces is related to their face discrimination abilities. To investigate this question we conducted a habituation-dishabituation experiment to examine Caucasian 9-month-old infants' gaze behavior, and their discrimination of same- and other-race faces, using eye-tracking measurements. We found that infants looked longer at the eyes of same-race faces over the course of habituation, as compared to other-race faces. After habituation, infants demonstrated a clear other-race effect by successfully discriminating between same-race faces, but not other-race faces. Importantly, the infants' ability to discriminate between same-race faces significantly correlated with their fixation time towards the eyes of same-race faces during habituation. Thus, our findings suggest that for infants old enough to begin exhibiting the ORE, gaze behavior during habituation is related to their ability to differentiate among same-race faces, compared to other-race faces.

The Own-Race Bias for Face Recognition in a Multiracial Society

The own-race bias (ORB) is a reliable phenomenon across cultural and racial groups where unfamiliar faces from other races are usually remembered more poorly than own-race faces (Meissner and Brigham, 2001). By adopting a yes-no recognition paradigm, we found that ORB was pronounced across race groups (Malaysian-Malay, Malaysian-Chinese, Malaysian-Indian, and Western-Caucasian) when faces were presented with only internal features (Experiment 1), implying that growing up in a profoundly multiracial society does not necessarily eliminate ORB. Using a procedure identical to Experiment 1, we observed a significantly greater increment in recognition performance for other-race faces than for own-race faces when the external features (e.g. facial contour and hairline) were presented along with the internal features (Experiment 2)-this abolished ORB. Contrary to assumptions based on the contact hypothesis, participants' self-reported amount of interracial contact on a social contact questionnaire did not significantly predict the magnitude of ORB. Overall, our findings suggest that the level of exposure to other-race faces accounts for only a small part of ORB. In addition, the present results also support the notion that different neural mechanisms may be involved in processing own- and other-race faces, with internal features of own-race faces being processed more effectively, whereas external features dominate representations of other-race faces.

Effects of Baby Schema and Mere Exposure on Explicit and Implicit Face Processing

In an increasingly multicultural society, the way people perceive individuals from the same vs different ethnic groups greatly affects their own and societal well-being. Two psychological effects that influence these perceptions are the Mere-Exposure Effect (MRE), wherein familiarity with certain objects or persons suffices for people to develop a preference for them, and the Baby Schema (BS), a set of specific facial features that evokes caregiving behaviors and an affective orientation in adults. In the present study, we aimed to investigate whether these two effects play a role in implicit physiological responses to babies vs. adults faces belonging to participants in-group vs. out-group. In study 1, the pupillary diameter of 62 Caucasian participants (M = 31; F = 31) who observed adult and infant faces of different ethnic groups (Caucasian, Chinese) was measured. In study 2, brain waves of 38 Caucasian participants (M = 19; F = 19), who observed the same set of faces, were recorded using EEG. In both studies, adults explicit preferences (i.e., attitudes) toward faces were assessed using questionnaires. In Study 1, females showed greater attention to infant than adult faces (BS effect) in both pupils, regardless of the ethnic group of the face. By contrast, males attended to infant more than adult faces for out-group faces only (BS effect). In Study 2, greater left posterior-parietal alpha activation toward out-group compared to in-group adult faces was found in males (MRE). Participants with a low BS effect toward in-group baby faces exhibited greater left posterior alpha activation to out-group than in-group baby faces (MRE). These findings reveal how different levels of sensitivity to in-group infants may moderate perceptions of both in-group and out-group baby faces. Questionnaire measures on attitudes showed that males and females preferred in-group to out-group adult faces (MRE). Participants in Study 2 also reported a greater preference for infants than adults faces (BS effect). These findings explicate the roles of gender and the Baby Schema effect in moderating implicit processing of in-group and out-group faces, despite their lack in moderating explicit reports. Contradictory findings at the implicit (physiological) and explicit (self-report) levels suggest that differential processing of faces may occur at a non-conscious level.

Cortical modulation of pupillary function: systematic review

BACKGROUND

The pupillary light reflex is the main mechanism that regulates the pupillary diameter; it is controlled by the autonomic system and mediated by subcortical pathways. In addition, cognitive and emotional processes influence pupillary function due to input from cortical innervation, but the exact circuits remain poorly understood. We performed a systematic review to evaluate the mechanisms behind pupillary changes associated with cognitive efforts and processing of emotions and to investigate the cerebral areas involved in cortical modulation of the pupillary light reflex.

METHODOLOGY

We searched multiple databases until November 2018 for studies on cortical modulation of pupillary function in humans and non-human primates. Of 8,809 papers screened, 258 studies were included.

RESULTS

Most investigators focused on pupillary dilatation and/or constriction as an index of cognitive and emotional processing, evaluating how changes in pupillary diameter reflect levels of attention and arousal. Only few tried to correlate specific cerebral areas to pupillary changes, using either cortical activation models (employing micro-stimulation of cortical structures in non-human primates) or cortical lesion models (e.g., investigating patients with stroke and damage to salient cortical and/or subcortical areas). Results suggest the involvement of several cortical regions, including the insular cortex (Brodmann areas 13 and 16), the frontal eye field (Brodmann area 8) and the prefrontal cortex (Brodmann areas 11 and 25), and of subcortical structures such as the locus coeruleus and the superior colliculus.

CONCLUSIONS

Pupillary dilatation occurs with many kinds of mental or emotional processes, following sympathetic activation or parasympathetic inhibition. Conversely, pupillary constriction may occur with anticipation of a bright stimulus (even in its absence) and relies on a parasympathetic activation. All these reactions are controlled by subcortical and cortical structures that are directly or indirectly connected to the brainstem pupillary innervation system.

Assessment of the Influence of "Other-Race Effect" on Visual Attention and Perception of Attractiveness Before and After Rhinoplasty

IMPORTANCE

The "other-race effect" describes the phenomenon in which individuals demonstrate greatest recognition ability among faces of their own race. Thus, in our multicultural world, it follows that race influences social interactions. However, the association of race with perception of plastic surgery outcomes has not been studied.

OBJECTIVE

To objectively measure how the other-race effect influences perception of white and Latin American patients undergoing rhinoplasty by using eye-tracking technology and survey methodology.

DESIGN, SETTING, AND PARTICIPANTS

In the first part of the study, 134 participants viewed 32 paired facial images of white and Latin American patients, either prerhinoplasty or postrhinoplasty, on an eye-tracking system that recorded observer scan paths. In the second part of this study, the same patient images were individually graded by a separate group of 134 participants for degree of racial identification and perceived attractiveness.

MAIN OUTCOMES AND MEASURES

The primary outcome was to measure the influence of patient and observer race on perception of rhinoplasty outcomes. For the eye-tracking part, planned hypothesis testing was conducted using an analysis of variance to compare patient race, rhinoplasty status, and attractiveness with respect to visual fixation time.

RESULTS

Of the 134 eye-tracking participants, 68 (51%) were women and the mean (SD) age was 26.4 (7.7) years; of the 134 graders, 64 (48%) were women and the mean (SD) age was 25.0 (6.9) years. Rhinoplasty did not affect racial identity scores among either same-race or other-race evaluators. Visual fixation times for white faces were significantly increased compared with Latin American faces among all casual observer groups (white observers mean change, -20.14 milliseconds; 95% CI, -29.65 to -10.62 milliseconds; P < .001; Asian observers mean change, -39.04 milliseconds; 95% CI, -48.95 to -29.15 milliseconds; P < .001; and African American observers mean change, -20.73 milliseconds; 95% CI, -37.78 to -3.69 milliseconds; P < .02), with the exception of Latin American observers (mean change, -7.8 milliseconds; 95% CI, -29.15 to 14.39 milliseconds; P < .51). With respect to attractiveness, white graders reported a significant postrhinoplasty increase across both races (white patients mean change, 8.07 points; 95% CI, 5.01-11.12 points; P < .001; and Latin American patients mean change, 3.69 points; 95% CI, 0.87-6.49 points; P = .01), whereas Latin American graders only observed a significant attractiveness increase in their own race (Latin American patients mean change, 10.50 points; 95% CI, 1.70-19.32 points; P = .02). Neither perceived attractiveness nor rhinoplasty status influenced fixation times.

CONCLUSIONS AND RELEVANCE

Both patient and observer race influence visual attention and perception of attractiveness before and after rhinoplasty. These findings underscore the importance of counseling patients that the influence of rhinoplasty, as perceived by the casual observer, may vary by race or ethnicity of the observer group.

LEVEL OF EVIDENCE

NA.

A dose-finding study of oxytocin using neurophysiological measures of social processing

Recent interest has focused on oxytocin (OT), a neurotransmitter that promotes social processing, to improve social functioning in people with schizophrenia. However, little information is available regarding the doses of OT that are effective for influencing social processing in the brain (i.e., target engagement). In this study, we conducted a double-blind, placebo-controlled, cross-over dose ranging study of OT. In total 47 patients with schizophrenia were randomly assigned to one of eight doses of OT (8, 12, 24, 36, 48, 60, 72, or 84 IU). Patients completed two social processing tasks: one electroencephalography (EEG) task, a biological motion Mu-suppression task (i.e., identifying the gender, emotion, or direction of walking of point-light animations of human movement); and one pupillometry task, pupil dilation in response to viewing affective faces. Participants completed these tasks twice, one week apart, and were randomly administered drug or placebo intranasally 30 min prior to each session. Mu-suppression, i.e., suppression of oscillations in the 8-12 Hz range over central electrodes in response to social stimuli, was significantly enhanced at doses of 36 and 48 IU in comparison to placebo, but not at other doses. Significant pupil dilation was observed in response to faces vs. non-face stimuli, though there were no drug effects at any dose. Results suggest that OT affects central measures of social information processing in patients with schizophrenia and is optimal at a mid-range dose (36-48 IU). These results provide dosing guidance for future studies of OT to be used to enhance social processing in people with schizophrenia.

The Own-Race Bias and the cerebral hemispheres

The Own-Race Bias (ORB) is the ability to better recognize and categorize a face when the depicted person belongs to the observer's ethnicity group. The relationship between the ORB and hemispheric asymmetries has been poorly explored, and the present study was aimed at investigating this relationship, as well as that between the ORB and the bias to better recognize own gender faces. Female and male Caucasian participants categorized the ethnicity of Caucasian and Asian female and male facial stimuli in a divided visual field paradigm. In a control experiment the same stimuli were presented centrally, confirming the ORB. Importantly, the lateralized presentation reversed the bias with higher accuracy and shorter response times in the categorization of Asian than Caucasian faces. This reversed bias was significant for female and male faces, and it was observed when stimuli were presented in the left but not in the right visual field, revealing the crucial role of the right hemisphere in face processing. These results shed new light on the hemispheric abilities in the categorization of facial features, and they are compared to previous evidence of cerebral asymmetries for facial age, gender and identity, both in healthy participants and in neurological patients.

The "face race lightness illusion": An effect of the eyes and pupils?

In an internet-based, forced-choice, test of the ‘face race lightness illusion’, the majority of respondents, regardless of their ethnicity, reported perceiving the African face as darker in skin tone than the European face, despite the mean luminance, contrast and numbers of pixels of the images were identical. In the laboratory, using eye tracking, it was found that eye fixations were distributed differently on the African face and European face, so that gaze dwelled relatively longer onto the locally brighter regions of the African face and, in turn, mean pupil diameters were smaller than for the European face. There was no relationship between pupils’ size and implicit social attitude (IAT) scores. In another experiment, the faces were presented either tachistoscopically (140 ms) or longer (2500 ms) so that, when gaze was prevented from looking directly at the faces in the former condition, the tendency to report the African face as “dark” disappeared, but it was present when gaze was free to move for just a few seconds. We conclude that the presence of the illusion depends on oculomotor behavior and we also propose a novel account based on a predictive strategy of sensory acquisition. Specifically, by differentially directing gaze towards to facial regions that are locally different in luminance, the resulting changes in retinal illuminance yield respectively darker or brighter percepts while attending to each face, hence minimizing the mismatch between visual input and the learned perceptual prototypes of ethnic categories.

In-group biases and oculomotor responses: beyond simple approach motivation

An in-group bias describes an individual’s bias towards a group that they belong to. Previous studies suggest that in-group bias facilitates approach motor responses, but disrupts avoidance ones. Such motor biases are shown to be more robust when the out-group is threatening. We investigated whether, under controlled visual familiarity and complexity, in-group biases still promote pro-saccade and hinder anti-saccades oculomotor responses. Participants first learned to associate an in-group or out-group label with an arbitrary shape. They were then instructed to listen to the group-relevant auditory cue (name of own and a rival university) followed by one of the shapes. Half of the participants were instructed to look towards the visual target if it matched the preceding group-relevant auditory cue and to look away from it if it did not match. The other half of the participants received reversed instructions. This design allowed us to orthogonally manipulate the effect of in-group bias and cognitive control demand on oculomotor responses. Both pro- and anti-saccades were faster and more accurate following the in-group auditory cue. Independently, pro-saccades were performed better than anti-saccades, and match judgements were faster and more accurate than non-match judgements. Our findings indicate that under higher cognitive control demands individuals’ oculomotor responses improved following the motivationally salient cue (in-group). Our findings have important implications for learning and cognitive control in a social context. As we included rival groups, our results might to some extent reflect the effects of out-group threat. Future studies could extend our findings using non-threatening out-groups instead.

Practice-induced and sequential modulations in the Simon task: evidence from pupil dilation

Recent evidence showed that pupil dilation (PD) reflects modulations in the magnitude of the Simon interference effect due to correspondence sequence. In the present study we used this measure to assess whether these modulations, thought to result from cognitive control mechanisms, are influenced by prior practice with an incompatible stimulus-response (S-R) mapping. To this end, PD and reaction times (RTs) were recorded while participants performed a Simon task before and after executing a spatially incompatible practice. The sequential analysis revealed that PD mirrored the conflict-adaptation pattern observed in RTs. Crucially, sequential modulations were not affected by prior practice. These findings support the view that the modulations of the Simon effect due to prior practice and those due to correspondence sequence result from two different mechanisms, and suggest that PD can help to better understand the mechanisms underlying response selection and cognitive control in the Simon task.

Differences in Looking at Own- and Other-Race Faces Are Subtle and Analysis-Dependent: An Account of Discrepant Reports

The Other-Race Effect (ORE) is the robust and well-established finding that people are generally poorer at facial recognition of individuals of another race than of their own race. Over the past four decades, much research has focused on the ORE because understanding this phenomenon is expected to elucidate fundamental face processing mechanisms and the influence of experience on such mechanisms. Several recent studies of the ORE in which the eye-movements of participants viewing own- and other-race faces were tracked have, however, reported highly conflicting results regarding the presence or absence of differential patterns of eye-movements to own- versus other-race faces. This discrepancy, of course, leads to conflicting theoretical interpretations of the perceptual basis for the ORE. Here we investigate fixation patterns to own- versus other-race (African and Chinese) faces for Caucasian participants using different analysis methods. While we detect statistically significant, though subtle, differences in fixation pattern using an Area of Interest (AOI) approach, we fail to detect significant differences when applying a spatial density map approach. Though there were no significant differences in the spatial density maps, the qualitative patterns matched the results from the AOI analyses reflecting how, in certain contexts, Area of Interest (AOI) analyses can be more sensitive in detecting the differential fixation patterns than spatial density analyses, due to spatial pooling of data with AOIs. AOI analyses, however, also come with the limitation of requiring a priori specification. These findings provide evidence that the conflicting reports in the prior literature may be at least partially accounted for by the differences in the statistical sensitivity associated with the different analysis methods employed across studies. Overall, our results suggest that detection of differences in eye-movement patterns can be analysis-dependent and rests on the assumptions inherent in the given analysis.

Initial eye movements during face identification are optimal and similar across cultures

Culture influences not only human high-level cognitive processes but also low-level perceptual operations. Some perceptual operations, such as initial eye movements to faces, are critical for extraction of information supporting evolutionarily important tasks such as face identification. The extent of cultural effects on these crucial perceptual processes is unknown. Here, we report that the first gaze location for face identification was similar across East Asian and Western Caucasian cultural groups: Both fixated a featureless point between the eyes and the nose, with smaller between-group than within-group differences and with a small horizontal difference across cultures (8% of the interocular distance). We also show that individuals of both cultural groups initially fixated at a slightly higher point on Asian faces than on Caucasian faces. The initial fixations were found to be both fundamental in acquiring the majority of information for face identification and optimal, as accuracy deteriorated when observers held their gaze away from their preferred fixations. An ideal observer that integrated facial information with the human visual system's varying spatial resolution across the visual field showed a similar information distribution across faces of both races and predicted initial human fixations. The model consistently replicated the small vertical difference between human fixations to Asian and Caucasian faces but did not predict the small horizontal leftward bias of Caucasian observers. Together, the results suggest that initial eye movements during face identification may be driven by brain mechanisms aimed at maximizing accuracy, and less influenced by culture. The findings increase our understanding of the interplay between the brain's aims to optimally accomplish basic perceptual functions and to respond to sociocultural influences.

Visual scanning behavior is related to recognition performance for own- and other-age faces

It is well-established that our recognition ability is enhanced for faces belonging to familiar categories, such as own-race faces and own-age faces. Recent evidence suggests that, for race, the recognition bias is also accompanied by different visual scanning strategies for own- compared to other-race faces. Here, we tested the hypothesis that these differences in visual scanning patterns extend also to the comparison between own and other-age faces and contribute to the own-age recognition advantage. Participants (young adults with limited experience with infants) were tested in an old/new recognition memory task where they encoded and subsequently recognized a series of adult and infant faces while their eye movements were recorded. Consistent with findings on the other-race bias, we found evidence of an own-age bias in recognition which was accompanied by differential scanning patterns, and consequently differential encoding strategies, for own-compared to other-age faces. Gaze patterns for own-age faces involved a more dynamic sampling of the internal features and longer viewing time on the eye region compared to the other regions of the face. This latter strategy was extensively employed during learning (vs. recognition) and was positively correlated to discriminability. These results suggest that deeply encoding the eye region is functional for recognition and that the own-age bias is evident not only in differential recognition performance, but also in the employment of different sampling strategies found to be effective for accurate recognition.

Visual scanning and recognition of Chinese, Caucasian, and racially ambiguous faces: contributions from bottom-up facial physiognomic information and top-down knowledge of racial categories

Recent studies have shown that participants use different eye movement strategies when scanning own- and other-race faces. However, it is unclear (1) whether this effect is related to face recognition performance, and (2) to what extent this effect is influenced by top-down or bottom-up facial information. In the present study, Chinese participants performed a face recognition task with Chinese, Caucasian, and racially ambiguous faces. For the racially ambiguous faces, we led participants to believe that they were viewing either own-race Chinese faces or other-race Caucasian faces. Results showed that (1) Chinese participants scanned the nose of the true Chinese faces more than that of the true Caucasian faces, whereas they scanned the eyes of the Caucasian faces more than those of the Chinese faces; (2) they scanned the eyes, nose, and mouth equally for the ambiguous faces in the Chinese condition compared with those in the Caucasian condition; (3) when recognizing the true Chinese target faces, but not the true target Caucasian faces, the greater the fixation proportion on the nose, the faster the participants correctly recognized these faces. The same was true when racially ambiguous face stimuli were thought to be Chinese faces. These results provide the first evidence to show that (1) visual scanning patterns of faces are related to own-race face recognition response time, and (2) it is bottom-up facial physiognomic information that mainly contributes to face scanning. However, top-down knowledge of racial categories can influence the relationship between face scanning patterns and recognition response time.

Pupil Dilation Reflects the Creation and Retrieval of Memories

It has long been known that pupils-the apertures that allow light into the eyes-dilate and constrict not only in response to changes in ambient light but also in response to emotional changes and arousing stimuli (e.g., Fontana, 1765). Charles Darwin (1872) related changes in pupil diameter to fear and other "emotions" in animals. For decades, pupillometry has been used to study cognitive processing across many domains, including perception, language, visual search, and short-term memory. Historically, such studies have examined the pupillary reflex as a correlate of attentional demands imposed by different tasks or stimuli-pupils typically dilate as cognitive demand increases. Because the neural mechanisms responsible for such task-evoked pupillary reflexes (TEPRs) implicate a role for memory processes, recent studies have examined pupillometry as a tool for investigating the cognitive processes underlying the creation of new episodic memories and their later retrieval. Here, we review the historical antecedents of current pupillometric research and discuss several recent studies linking pupillary dilation to the on-line consumption of cognitive resources in long-term-memory tasks. We conclude by discussing the future role of pupillometry in memory research and several methodological considerations that are important when designing pupillometric studies.