Ensemble Perception of Dynamic Emotional Groups

A cognitive template for human face detection

Faces are highly informative social stimuli, yet before any information can be accessed, the face must first be detected in the visual field. A detection template that serves this purpose must be able to accommodate the wide variety of face images we encounter, but how this generality could be achieved remains unknown. In this study, we investigate whether statistical averages of previously encountered faces can form the basis of a general face detection template. We provide converging evidence from a range of methods-human similarity judgements and PCA-based image analysis of face averages (Experiment 1-3), human detection behaviour for faces embedded in complex scenes (Experiment 4 and 5), and simulations with a template-matching algorithm (Experiment 6 and 7)-to examine the formation, stability and robustness of statistical image averages as cognitive templates for human face detection. We integrate these findings with existing knowledge of face identification, ensemble coding, and the development of face perception.

Other ethnicity effects in ensemble coding of facial expressions

Cultural difference in ensemble emotion perception is an important research question, providing insights into the complexity of human cognition and social interaction. Here, we conducted two experiments to investigate how emotion perception would be affected by other ethnicity effects and ensemble coding. In Experiment 1, two groups of Asian and Caucasian participants were tasked with assessing the average emotion of faces from their ethnic group, other ethnic group, and mixed ethnicity groups. Results revealed that participants exhibited relatively accurate yet amplified emotion perception of their group faces, with a tendency to overestimate the weight of the faces from the other ethnic group. In Experiment 2, Asian participants were instructed to discern the emotion of a target face surrounded by faces from Caucasian and Asian faces. Results corroborated earlier findings, indicating that while participants accurately perceived emotions in faces of their ethnicity, their perception of Caucasian faces was noticeably influenced by the presence of surrounding Asian faces. These findings collectively support the notion that the other ethnicity effect stems from differential emotional amplification inherent in ensemble coding of emotion perception.

The combination operation of grouping and ensemble coding for structured biological motion crowds in working memory

Massive studies have explored biological motion (BM) crowds processing for their remarkable social significance, primarily focused on uniformly distributed ones. However, real-world BM crowds often exhibit hierarchical structures rather than uniform arrangements. How such structured BM crowds are processed remains a subject of inquiry. This study investigates the representation of structured BM crowds in working memory (WM), recognizing the pivotal role WM plays in our social interactions involving BM. We propose the group-based ensemble hypothesis and test it through a member identification task. Participants were required to discern whether a presented BM belonged to a prior memory display of eight BM, each with distinct walking directions. Drawing on prominent Gestalt principles as organizational cues, we constructed structured groups within BM crowds by applying proximity and similarity cues in Experiments 1 and 2, respectively. In Experiment 3, we deliberately weakened the visibility of stimuli structures by increasing the similarity between subsets, probing the robustness of results. Consistently, our findings indicate that BM aligned with the mean direction of the subsets was more likely to be recognized as part of the memory stimuli. This suggests that WM inherently organizes structured BM crowds into separate ensembles based on organizational cues. In essence, our results illuminate the simultaneous operation of grouping and ensemble encoding mechanisms for BM crowds within WM.

Similarity in motion binds and bends judgments of aspect ratio

It is well known that objects become grouped in perceptual organization when they share some visual feature, like a common direction of motion. Less well known is that grouping can change how people perceive a set of objects. For example, when a pair of shapes consistently share a common region of space, their aspect ratios tend to be perceived as more similar (are attracted toward each other). Conversely, when shapes are assigned to different regions in space their aspect ratios repel from each other. Here we examine whether the visual system produce both attractive and repulsive distortions when the state of grouping between a pair of shapes changes on a moment-to-moment basis. Observers viewed a pair of ellipses that differed in terms of how flat or tall they were and reported the aspect ratio of one ellipse from the pair. Each ellipse was defined by a cloud of coherently-moving dots, and the dots within the two ellipses had either the same or different directions of motion, varying from trial-to-trial. We found that the cued ellipse's aspect ratio was reported to be repelled from the aspect ratio of the uncued ellipse when the shapes had different directions of motion compared to when they had the same direction of motion. These results suggest that the visual system can adaptively alter visual experience based on grouping, in particular, repelling the appearance of objects when they do not appear to go together, and it can do so quickly and flexibly.

Evidence for a role of synchrony but not common fate in the perception of biological group movements

Extensive research has shown that observers are able to efficiently extract summary information from groups of people. However, little is known about the cues that determine whether multiple people are represented as a social group or as independent individuals. Initial research on this topic has primarily focused on the role of static cues. Here, we instead investigate the role of dynamic cues. In two experiments with male and female human participants, we use EEG frequency tagging to investigate the influence of two fundamental Gestalt principles - synchrony and common fate - on the grouping of biological movements. In Experiment 1, we find that brain responses coupled to four point-light figures walking together are enhanced when they move in sync vs. out of sync, but only when they are presented upright. In contrast, we found no effect of movement direction (i.e., common fate). In Experiment 2, we rule out that synchrony takes precedence over common fate by replicating the null effect of movement direction while keeping synchrony constant. These results suggest that synchrony plays an important role in the processing of biological group movements. In contrast, the role of common fate is less clear and will require further research.

Ensemble Coding of Crowd with Cross-Category Facial Expressions

Ensemble coding allows observers to form an average to represent a set of elements. However, it is unclear whether observers can extract an average from a cross-category set. Previous investigations on this issue using low-level stimuli yielded contradictory results. The current study addressed this issue by presenting high-level stimuli (i.e., a crowd of facial expressions) simultaneously (Experiment 1) or sequentially (Experiment 2), and asked participants to complete a member judgment task. The results showed that participants could extract average information from a group of cross-category facial expressions with a short perceptual distance. These findings demonstrate cross-category ensemble coding of high-level stimuli, contributing to the understanding of ensemble coding and providing inspiration for future research.

How do students reason about statistical sampling with computer simulations? An integrative review from a grounded cognition perspective

Interactive computer simulations are commonly used as pedagogical tools to support students' statistical reasoning. This paper examines whether and how these simulations enable their intended effects. We begin by contrasting two theoretical frameworks-dual processes and grounded cognition-in the context of people's conceptions about statistical sampling, setting the stage for the potential benefits of simulations in learning such conceptions. Then, we continue with reviewing the educational literature on statistical sampling simulations. Our review tentatively suggests benefits of the simulations for building statistical habits of mind. However, challenges seem to persist when more specific concepts and skills are investigated. With and without simulations, students have difficulty forming an aggregate view of data, interpreting sampling distributions, showing a process-based understanding of the law of large numbers, making statistical inferences, and context-independent reasoning. We propose that grounded cognition offers a framework for understanding these findings, highlighting the bidirectional relationship between perception and conception, perceptual design features, and guided perceptual routines for supporting students' meaning making from simulations. Finally, we propose testable instructional strategies for using simulations in statistics education.

What Makes Groups Emotional?

When people experience emotions in a group, their emotions tend to have stronger intensity and to last longer. Why is that? This question has occupied thinkers throughout history, and with the use of digital media it is even more pressing today. Historically, attention has mainly focused on processes driven by the way emotions are shared between people via emotional interactions. Although interactions are a major driver of group emotionality, I review empirical findings that suggest that understanding group emotionality requires a broader view that integrates two additional processes: how emotions unfold within the social infrastructure in which they are shared and how these processes are affected by people's cognition about emotions. I propose to summarize the literature using an infrastructure-cognition-interaction framework that contributes to a broader understanding of group emotionality, which should improve our ability to predict group emotionality and to change these emotions when they are undesired.

Perceiving the outlier in the crowd: The influence of facial identity

The accurate perception of groups with outliers can help us identify potential risks. However, it is unclear how outliers affect the perception of group emotion. To address this question, we conducted a study on group emotion perception in the context of facial identity. We presented 74 participants with pictures of crowds, and asked them to evaluate the valence ratios and intensity of the crowd by means of the Emotional Aperture Measure. The results revealed that outlier emotions were often overestimated within crowds. Moreover, we found that the emotional expression of a close friend modulated the perception of outliers. Specifically, when a close friend expressed the group emotion, participants overestimated the outlier less than when a close friend expressed the outlier emotion. These results suggest that people can detect outliers within groups, and that their perception of group emotion is influenced by close friends. Thus, we provide evidence that facial identity affects group emotion perception.

The Impact of Spatial Frequency on the Perception of Crowd Emotion: An fMRI Study

Recognizing the emotions of faces in a crowd is crucial for understanding overall behavior and intention as well as for smooth and friendly social interactions. However, it is unclear whether the spatial frequency of faces affects the discrimination of crowd emotion. Although high- and low-spatial-frequency information for individual faces is processed by distinct neural channels, there is a lack of evidence on how this applies to crowd faces. Here, we used functional magnetic resonance imaging (fMRI) to investigate neural representations of crowd faces at different spatial frequencies. Thirty-three participants were asked to compare whether a test face was happy or more fearful than a crowd face that varied in high, low, and broad spatial frequencies. Our findings revealed that fearful faces with low spatial frequencies were easier to recognize in terms of accuracy (78.9%) and response time (927 ms). Brain regions, such as the fusiform gyrus, located in the ventral visual stream, were preferentially activated in high spatial frequency crowds, which, however, were the most difficult to recognize behaviorally (68.9%). Finally, the right inferior frontal gyrus was found to be better activated in the broad spatial frequency crowds. Our study suggests that people are more sensitive to fearful crowd faces with low spatial frequency and that high spatial frequency does not promote crowd face recognition.

The background assimilation effect: Facial emotional perception is affected by surrounding stimuli

The perception of facial emotion is not only determined by the physical features of the face itself but also be influenced by the emotional information of the background or surrounding information. However, the details of such effect are not fully understood. Here, the authors tested the perceived emotion of a target face surrounded by stimuli with different levels of emotional valence. In Experiment 1, four types of objects were divided into three groups (negative, unpleasant flowers and unpleasant animals; mildly negative (neutral), houses; positive, pleasant flowers). In Experiment 2, three groups of surrounding faces with different social-emotional valence (negative, neutral, and positive) were formed with the memory of affective personal knowledge. The data from two experiments showed that the perception of facial emotion can be influenced and modulated by the emotional valence of the surrounding stimuli, which can be explained by assimilation: the positive stimuli increased the valence of a target face, while the negative stimuli comparatively decreased it. Furthermore, the neutral stimuli also increased the valence of the target, which could be explained by the social positive effect. Therefore, the process of assimilation is likely to be a high-level emotional cognition rather than a low-level visual perception. The results of this study may help us better understand face perception in realistic scenarios.

Teams moving more synchronously are perceived as socially dominant

Characteristics indicative of individual and group power can be used to judge social dominance. The present study investigated whether observers use movement synchrony to judge the dominance of teams during a social conflict. How synchronously individuals move together has been found to influence judgments of team effectiveness and the formidability of groups. Across four experiments, the present study examined whether movement synchrony is also used as a cue of team dominance. Experiment 1 provided evidence that teams of animated characters with higher movement synchrony were judged as more likely to win a competition and were rated as more dominant. A similar effect of synchrony on teams winning a competition was observed in Experiment 2 with different types of movement. Experiment 3 replicated the effects of the prior experiments: teams that moved more synchronously were judged as more likely to win a competition and rated as more socially dominant. These effects were extended in Experiment 4 with a new set of stimuli, human-like avatars performing complex dance actions, replicating synchrony-effects with different types of characters. This research indicates that human observers use movement synchrony to judge the social dominance of teams. This expands the types of behavioral cues that are used to predict the power of teams when social conflicts occur.

Amplification in the evaluation of multiple emotional expressions over time

Social interactions are dynamic and unfold over time. To make sense of social interactions, people must aggregate sequential information into summary, global evaluations. But how do people do this? Here, to address this question, we conducted nine studies (N = 1,583) using a diverse set of stimuli. Our focus was a central aspect of social interaction-namely, the evaluation of others' emotional responses. The results suggest that when aggregating sequences of images and videos expressing varying degrees of emotion, perceivers overestimate the sequence's average emotional intensity. This tendency for overestimation is driven by stronger memory of more emotional expressions. A computational model supports this account and shows that amplification cannot be explained only by nonlinear perception of individual exemplars. Our results demonstrate an amplification effect in the perception of sequential emotional information, which may have implications for the many types of social interactions that involve repeated emotion estimation.

Attention Modulates the Ensemble Coding of Facial Expressions

Ensemble coding and attention are two mechanisms utilized by our visual system to overcome the limitation of visual processing when confronted with the overwhelming visual information. Recent evidence in ensemble coding of size suggests that the attended items contributed more to the averaging. On the other hand, some new evidence also indicates that reduced attention jeopardies the perceptual averaging of stimuli. What is the relationship between attention and ensemble coding? To answer this question, in the current study, we tested whether an exogenous attentional cue would influence the reported mean emotion of a crowd. We showed participants a group of four faces with different emotions. Participants' attention was guided to the happiest or saddest face (attention conditions), or not to any specific face (baseline condition). The results supported the notion that the attention alters the ensemble perception of the facial expression by elevating the weight of that face in the ensemble representation. This opens the question for the neural mechanisms of ensemble coding and its connection to visual attention.

Person Perception, Meet People Perception: Exploring the Social Vision of Groups

Groups, teams, and collectives-people-are incredibly important to human behavior. People live in families, work in teams, and celebrate and mourn together in groups. Despite the huge variety of human group activity and its fundamental importance to human life, social-psychological research on person perception has overwhelmingly focused on its namesake, the person, rather than expanding to consider people perception. By looking to two unexpected partners, the vision sciences and organization behavior, we find emerging work that presents a path forward, building a foundation for understanding how people perceive other people. And yet this nascent field is missing critical insights that scholars of social vision might offer: specifically, for example, the chance to connect perception to behavior through the mediators of cognition and motivational processes. Here, we review emerging work across the vision and social sciences to extract core principles of people perception: efficiency, capacity, and complexity. We then consider complexity in more detail, focusing on how people perception modifies person-perception processes and enables the perception of group emergent properties as well as group dynamics. Finally, we use these principles to discuss findings and outline areas fruitful for future work. We hope that fellow scholars take up this people-perception call.

Ensemble coding of average length and average orientation are correlated

Viewers can summarize redundant features in groups of objects into an ensemble percept. There appears to be separate mechanisms underlying ensemble perception of low- and high-level visual features, but it is unclear whether ensemble perception of different low-level features is supported by common mechanisms. Yörük and Boduroglu, in Attention, Perception, & Psychophysics 82 (2020) 852-864, investigated whether length and orientation summarization tap common mechanisms by examining the correlation between errors on length- and orientation-averaging tasks and concluded that because they did not find any correlations, the two features are summarized by different, feature-specific mechanisms. However, their study was conducted with a small sample size and included sources of individual performance variance that may have diminished correlations. We report two studies that tested the correlation between performance in the length- and orientation-averaging tasks, with larger samples and modifications that sought to reduce the sources of variance. Study 1 used ensembles that varied in both feature dimensions and Study 2 used ensembles that only varied in the task-relevant dimension. Both studies showed that errors in length- and orientation-averaging are correlated, suggesting that ensemble perception of these low-level features is supported, at least to some extent, by a common ability.

Differential neurodynamics and connectivity in the dorsal and ventral visual pathways during perception of emotional crowds and individuals: a MEG study

Reading the prevailing emotion of groups of people ("crowd emotion") is critical to understanding their overall intention and disposition. It alerts us to potential dangers, such as angry mobs or panicked crowds, giving us time to escape. A critical aspect of processing crowd emotion is that it must occur rapidly, because delays often are costly. Although knowing the timing of neural events is crucial for understanding how the brain guides behaviors using coherent signals from a glimpse of multiple faces, this information is currently lacking in the literature on face ensemble coding. Therefore, we used magnetoencephalography to examine the neurodynamics in the dorsal and ventral visual streams and the periamygdaloid cortex to compare perception of groups of faces versus individual faces. Forty-six participants compared two groups of four faces or two individual faces with varying emotional expressions and chose which group or individual they would avoid. We found that the dorsal stream was activated as early as 68 msec after the onset of stimuli containing groups of faces. In contrast, the ventral stream was activated later and predominantly for individual face stimuli. The latencies of the dorsal stream activation peaks correlated with participants' response times for facial crowds. We also found enhanced connectivity earlier between the periamygdaloid cortex and the dorsal stream regions for crowd emotion perception. Our findings suggest that ensemble coding of facial crowds proceeds rapidly and in parallel by engaging the dorsal stream to mediate adaptive social behaviors, via a distinct route from single face perception.

Holistic ensemble perception

In a glance, observers can evaluate gist characteristics from crowds of faces, such as the average emotional tenor or the average family resemblance. Prior research suggests that high-level ensemble percepts rely on holistic and viewpoint-invariant information. However, it is also possible that feature-based analysis was sufficient to yield successful ensemble percepts in many situations. To confirm that ensemble percepts can be extracted holistically, we asked observers to report the average emotional valence of Mooney face crowds. Mooney faces are two-tone, shadow-defined images that cannot be recognized in a part-based manner. To recognize features in a Mooney face, one must first recognize the image as a face by processing it holistically. Across experiments, we demonstrated that observers successfully extracted the average emotional valence from crowds that were spatially distributed or viewed in a rapid temporal sequence. In a subsequent set of experiments, we maximized holistic processing by including only those Mooney faces that were difficult to recognize when inverted. Under these conditions, participants remained highly sensitive to the average emotional valence of Mooney face crowds. Taken together, these experiments provide evidence that ensemble perception can operate selectively on holistic representations of human faces, even when feature-based information is not readily available.

Ensemble coding of crowd speed using biological motion

The accurate perception of human crowds is integral to social understanding and interaction. Previous studies have shown that observers are sensitive to several crowd characteristics such as average facial expression, gender, identity, joint attention, and heading direction. In two experiments, we examined ensemble perception of crowd speed using standard point-light walkers (PLW). Participants were asked to estimate the average speed of a crowd consisting of 12 figures moving at different speeds. In Experiment 1, trials of intact PLWs alternated with trials of scrambled PLWs with a viewing duration of 3 seconds. We found that ensemble processing of crowd speed could rely on local motion alone, although a globally intact configuration enhanced performance. In Experiment 2, observers estimated the average speed of intact-PLW crowds that were displayed at reduced viewing durations across five blocks of trials (between 2500 ms and 500 ms). Estimation of fast crowds was precise and accurate regardless of viewing duration, and we estimated that three to four walkers could still be integrated at 500 ms. For slow crowds, we found a systematic deterioration in performance as viewing time reduced, and performance at 500 ms could not be distinguished from a single-walker response strategy. Overall, our results suggest that rapid and accurate ensemble perception of crowd speed is possible, although sensitive to the precise speed range examined.

Ensemble perception includes information from multiple spatial scales

Most visual scenes contain information at different spatial scales, including the local and global, or the detail and gist. Global processes have become increasingly implicated in research examining summary statistical perception, initially as the output of ensemble coding, and more recently as a gating mechanism for selecting which information is included in the averaging process itself. Yet local and global processing are known to be rapidly integrated by the visual system, and it is plausible that global-level information, like spatial organization, may be included as an input during ensemble coding. We tested this hypothesis using an ensemble shape-perception task in which observers evaluated the mean aspect ratios of sets of ellipses. In addition to varying the aspect ratios of the individual shapes, we independently varied the spatial arrangements of the sets so that they had either flat or tall organizations at the global level. We found that observers made precise summary judgments about the average aspect ratios of the sets by integrating information from multiple shapes. More importantly, global flat and tall organizations were incorporated into ensemble judgments about the sets; summary judgments were biased in the directions of the global spatial arrangements on each trial. This global-to-local integration even occurred when the global organizations were masked. Our results demonstrate that the process of summary representation can include information from both the local and global scales. The gist is not just an output of ensemble representation - it can be included as an input to the mechanism itself.

The role of category- and exemplar-specific experience in ensemble processing of objects

People can relatively easily report summary properties for ensembles of objects, suggesting that this information can enrich visual experience and increase the efficiency of perceptual processing. Here, we ask whether the ability to judge diversity within object arrays improves with experience. We surmised that ensemble judgments would be more accurate for commonly experienced objects, and perhaps even more for objects of expertise like faces. We also expected improvements in ensemble processing with practice with a novel category, and perhaps even more with repeated experience with specific exemplars. We compared the effect of experience on diversity judgments for arrays of objects, with participants being tested with either a small number of repeated exemplars or with a large number of exemplars from the same object category. To explore the role of more prolonged experience, we tested participants with completely novel objects (random blobs), with objects familiar at the category level (cars), and with objects with which observers are experts at subordinate-level recognition (faces). For objects that are novel, participants showed evidence of improved ability to distribute attention. In contrast, for object categories with long-term experience, i.e., faces and cars, performance improved during the experiment but not necessarily due to improved ensemble processing. Practice with specific exemplars did not result in better diversity judgments for all object categories. Considered together, these results suggest that ensemble processing improves with experience. However, experience operates rapidly, the role of experience does not rely on exemplar-level knowledge and may not benefit from subordinate-level expertise.

Contrast Effect of Facial Attractiveness in Groups

Research on facial attractiveness is an important part of aesthetics. Most relevant studies in the area have focused on the influence of individual perspectives on facial attractiveness, but it is necessary to consider the effect of contextual information on facial attractiveness. In this study, we examine the influence on attractiveness of special faces in a given group. We define a “special face” as one that is significantly different from other members of the same group in terms of facial attractiveness. We conducted three experiments to explore the influence of different modes of presentation and central positions in a group on the judgment of attractiveness of the special face. The results show the following: (1) When the special face was part of a given group, the subjects made more extreme judgments than without it: that is, they judged the most attractive face as more attractive and the least as less attractive than when faces were presented alone. (2) The subjects rated the most attractive faces lower and the least attractive faces higher when the target faces in the middle of the group than in other positions. The results favored the contrast effect: when the subjects judged the attractiveness of target stimulus, they always compared it with the environment, which then became a reference in this regard. Moreover, the greater the amount of contextual information perceived, the higher the likelihood that assimilation would occur.

Ensemble coding of color and luminance contrast

Ensemble coding has been demonstrated for many attributes including color, but the metrics on which this coding is based remain uncertain. We examined ensemble percepts for stimulus sets that varied in chromatic contrast between complementary hues, or that varied in luminance contrast between increments and decrements, in both cases focusing on the ensemble percepts for the neutral gray stimulus defining the category boundary. Each ensemble was composed of 16 circles with four contrast levels. Observers saw the display for 0.5 s and then judged whether a target contrast was a member of the set. False alarms were high for intermediate contrasts (within the range of the ensemble) and fell for higher or lower values. However, for ensembles with complementary hues, gray was less likely to be reported as a member, even when it represented the mean chromaticity of the set. When the settings were repeated for luminance contrast, false alarms for gray were higher and fell off more gradually for out-of-range contrasts. This difference implies that opposite luminance polarities represent a more continuous perceptual dimension than opponent-color variations, and that "gray" is a stronger category boundary for chromatic than luminance contrasts. For color, our results suggest that ensemble percepts reflect pooling within rather than between large hue differences, perhaps because the visual system represents hue differences more like qualitatively different categories than like quantitative differences within an underlying color "space." The differences for luminance and color suggest more generally that ensemble coding for different visual attributes might depend on different processes that in turn depend on the format of the visual representation.

A crowd of emotional voices influences the perception of emotional faces: Using adaptation, stimulus salience, and attention to probe audio-visual interactions for emotional stimuli

Correctly assessing the emotional state of others is a crucial part of social interaction. While facial expressions provide much information, faces are often not viewed in isolation, but occur with concurrent sounds, usually voices, which also provide information about the emotion being portrayed. Many studies have examined the crossmodal processing of faces and sounds, but results have been mixed, with different paradigms yielding different results. Using a psychophysical adaptation paradigm, we carried out a series of four experiments to determine whether there is a perceptual advantage when faces and voices match in emotion (congruent), versus when they do not match (incongruent). We presented a single face and a crowd of voices, a crowd of faces and a crowd of voices, a single face of reduced salience and a crowd of voices, and tested this last condition with and without attention directed to the emotion in the face. While we observed aftereffects in the hypothesized direction (adaptation to faces conveying positive emotion yielded negative, contrastive, perceptual aftereffects), we only found a congruent advantage (stronger adaptation effects) when faces were attended and of reduced salience, in line with the theory of inverse effectiveness.

Pretty crowds are happy crowds: the influence of attractiveness on mood perception

Empirical findings predominantly support a happiness superiority effect in visual search and emotion categorization paradigms and reveal that social cues, like sex and race, moderate this advantage. A more recent study showed that the facial attribute attractiveness also influences the accuracy and speed of emotion perception. In the current study, we investigated whether the influence of attractiveness on emotion perception translates into a more general evaluation of moods when more than one emotional target is presented. In two experiments, we used the mood-of-the-crowd (MoC) task to investigate whether attractive crowds are perceived more positively compared to less attractive crowds. The task was to decide whether an array of faces included more angry or more happy faces. Furthermore, we recorded gaze movements to test the assumption that fixations on happy expressions occur more often in attractive crowds. Thirty-four participants took part in experiment 1 as well as in experiment 2. In both experiments, crowds presenting attractive faces were judged as being happy more frequently whereas the reverse pattern was found for unattractive crowds of faces. Moreover, participants were faster and more accurate when evaluating attractive crowds containing more happy faces as well as when judging unattractive crowds composed of more angry expressions. Additionally, in experiment 1, there were more fixations on happy compared to angry expressions in attractive crowds. Overall, the present findings support the assumption that attractiveness moderates emotion perception.

Facial expressions of authenticity: Emotion variability increases judgments of trustworthiness and leadership

People automatically generate first impressions from others' faces, even with limited time and information. Most research on social face evaluation focuses on static morphological features that are embedded "in the face" (e.g., overall average of facial features, masculinity/femininity, cues related to positivity/negativity, etc.). Here, we offer the first investigation of how variability in facial emotion affects social evaluations. Participants evaluated targets that, over time, displayed either high-variability or low-variability distributions of positive (happy) and/or negative (angry/fearful/sad) facial expressions, despite the overall averages of those facial features always being the same across conditions. We found that high-variability led to consistently positive perceptions of authenticity, and thereby, judgments of perceived happiness, trustworthiness, leadership, and team-member desirability. We found these effects were based specifically in variability in emotional displays (not intensity of emotion), and specifically increased the positivity of social judgments (not their extremity). Overall, people do not merely average or summarize over facial expressions to arrive at a judgment, but instead also draw inferences from the variability of those expressions.

Capacity limitations to extract the mean emotion from multiple facial expressions depend on emotion variance

We examined the processing capacity and the role of emotion variance in ensemble representation for multiple facial expressions shown concurrently. A standard set size manipulation was used, whereby the sets consisted of 4, 8, or 16 morphed faces each uniquely varying along a happy-angry continuum (Experiment 1) or a neutral-happy/angry continuum (Experiments 2 & 3). Across the three experiments, we reduced the amount of emotion variance in the sets to explore the boundaries of this process. Participants judged the perceived average emotion from each set on a continuous scale. We computed and compared objective and subjective difference scores, using the morph units and post-experiment ratings, respectively. Results of the subjective scores were more consistent than the objective ones across the first two experiments where the variance was relatively large, and revealed each time that increasing set size led to a poorer averaging ability, suggesting capacity limitations in establishing ensemble representations for multiple facial expressions. However, when the emotion variance in the sets was reduced in Experiment 3, both subjective and objective scores remained unaffected by set size, suggesting that the emotion averaging process was unlimited in these conditions. Collectively, these results suggest that extracting mean emotion from a set composed of multiple faces depends on both structural (attentional) and stimulus-related effects.

Perceptual averaging of facial expressions requires visual awareness and attention

Humans, as highly social animals, are regularly exposed to the faces of conspecifics-often more than one at a time. This feature of social living is important for understanding face perception, not just because it means that information from faces is available in bulk, but also because it changes the way individuals are perceived. For instance, when two faces are seen nearby one another, they tend to look like each other. This phenomenon of perceptual averaging is robust when both faces are seen and attended. But in everyday life, some faces may not receive the full benefit of attention, or they may not be visible at all. We evaluated whether perceptual averaging of relatively complex and simple information on faces, including facial expression and head orientation, can still occur even in these circumstances. In particular, we used object-substitution masking (OSM) and a dual-task designed to disrupt visual awareness and attention, respectively, during evaluations of briefly presented face pairs. Disruptions of awareness or attention eliminated averaging of facial expression, whereas orientation averaging persisted in spite of these challenges. These results demonstrate boundary conditions for the process of perceptual averaging. More generally, they provide insight into how the visual system processes multitudes of objects, both simple and complex, both with and without attention and awareness.

Perceived Average Orientation Reflects Effective Gist of the Surface

The human ability to represent ensemble visual information, such as average orientation and size, has been suggested as the foundation of gist perception. To effectively summarize different groups of objects into the gist of a scene, observers should form ensembles separately for different groups, even when objects have similar visual features across groups. We hypothesized that the visual system utilizes perceptual groups characterized by spatial configuration and represents separate ensembles for different groups. Therefore, participants could not integrate ensembles of different perceptual groups on a task basis. We asked participants to determine the average orientation of visual elements comprising a surface with a contour situated inside. Although participants were asked to estimate the average orientation of all the elements, they ignored orientation signals embedded in the contour. This constraint may help the visual system to keep the visual features of occluding objects separate from those of the occluded objects.

Cross-cultural and hemispheric laterality effects on the ensemble coding of emotion in facial crowds

In many social situations, we make a snap judgment about crowds of people relying on their overall mood (termed "crowd emotion"). Although reading crowd emotion is critical for interpersonal dynamics, the sociocultural aspects of this process have not been explored. The current study examined how culture modulates the processing of crowd emotion in Korean and American observers. Korean and American (non-East Asian) participants were briefly presented with two groups of faces that were individually varying in emotional expressions and asked to choose which group between the two they would rather avoid. We found that Korean participants were more accurate than American participants overall, in line with the framework on cultural viewpoints: Holistic versus analytic processing in East Asians versus Westerners. Moreover, we found a speed advantage for other-race crowds in both cultural groups. Finally, we found different hemispheric lateralization patterns: American participants were more accurate to perceive the facial crowd to be avoided when it was presented in the left visual field than the right visual field, indicating a right hemisphere advantage for processing crowd emotion of both European American and Korean facial crowds. However, Korean participants showed weak or nonexistent laterality effects, with a slight right hemisphere advantage for European American facial crowds and no advantage in perceiving Korean facial crowds. Instead, Korean participants showed positive emotion bias for own-race faces. This work suggests that culture plays a role in modulating our crowd emotion perception of groups of faces and responses to them.