Individual differences in the recognition of enjoyment smiles: no role for perceptual-attentional factors and autistic-like traits

Can group membership modulate the social abilities of autistic people? An intergroup bias in smile perception

Autistic adults struggle to reliably differentiate genuine and posed smiles. Intergroup bias is a promising factor that may modulate smile discrimination performance, which has been shown in neurotypical adults, and which could highlight ways to make social interactions easier. However, it is not clear whether this bias also exists in autistic people. Thus, the current study aimed to investigate this in autism using a minimal group paradigm. Seventy-five autistic and sixty-one non-autistic adults viewed videos of people making genuine or posed smiles and were informed (falsely) that some of the actors were from an in-group and others were from an out-group. The ability to identify smile authenticity of in-group and out-group members and group identification were assessed. Our results revealed that both groups seemed equally susceptible to ingroup favouritism, rating ingroup members as more genuine, but autistic adults also generally rated smiles as less genuine and were less likely to identify with ingroup members. Autistic adults showed reduced sensitivity to the different smile types but the absence of an intergroup bias in smile discrimination in both groups seems to indicate that membership can only modulate social judgements but not social abilities. These findings suggest a reconsideration of past findings that might have misrepresented the social judgements of autistic people through introducing an outgroup disadvantage, but also a need for tailored support for autistic social differences that emphasizes similarity and inclusion between diverse people.

Are adaptation aftereffects for facial emotional expressions affected by prior knowledge about the emotion?

Accurate perception of the emotional signals conveyed by others is crucial for successful social interaction. Such perception is influenced not only by sensory input, but also by knowledge we have about the others' emotions. This study addresses the issue of whether knowing that the other's emotional state is congruent or incongruent with their displayed emotional expression ("genuine" and "fake", respectively) affects the neural mechanisms underpinning the perception of their facial emotional expressions. We used a visual adaptation paradigm to investigate this question in three experiments employing increasing adaptation durations. The adapting stimuli consisted of photographs of emotional facial expressions of joy and anger, purported to reflect (in-)congruency between felt and expressed emotion, displayed by professional actors. A Validity checking procedure ensured participants had the correct knowledge about the (in-)congruency. Significantly smaller adaptation aftereffects were obtained when participants knew that the displayed expression was incongruent with the felt emotion, following all tested adaptation periods. This study shows that knowledge relating to the congruency between felt and expressed emotion modulates face expression aftereffects. We argue that this reflects that the neural substrate responsible for the perception of facial expressions of emotion incorporates the presumed felt emotion underpinning the expression.

The Glow Still Shows: Effects of Facial Masking on Perceptions of Duchenne Versus Social Smiles

Facial expressions of emotion have important communicative functions. It is likely that mask-wearing during pandemics disrupts these functions, especially for expressions defined by activity in the lower half of the face. We tested this by asking participants to rate both Duchenne smiles (DSs; defined by the mouth and eyes) and non-Duchenne or "social" smiles (SSs; defined by the mouth alone), within masked and unmasked target faces. As hypothesized, masked SSs were rated much lower in "a pleasant social smile" and much higher in "a merely neutral expression," compared with unmasked SSs. Essentially, masked SSs became nonsmiles. Masked DSs were still rated as very happy and pleasant, although significantly less so than unmasked DSs. Masked DSs and SSs were both rated as displaying more disgust than the unmasked versions.

Acting Surprised: Comparing Perceptions of Different Dynamic Deliberate Expressions

People are accurate at classifying emotions from facial expressions but much poorer at determining if such expressions are spontaneously felt or deliberately posed. We explored if the method used by senders to produce an expression influences the decoder’s ability to discriminate authenticity, drawing inspiration from two well-known acting techniques: the Stanislavski (internal) and Mimic method (external). We compared spontaneous surprise expressions in response to a jack-in-the-box (genuine condition), to posed displays of senders who either focused on their past affective state (internal condition) or the outward expression (external condition). Although decoders performed better than chance at discriminating the authenticity of all expressions, their accuracy was lower in classifying external surprise compared to internal surprise. Decoders also found it harder to discriminate external surprise from spontaneous surprise and were less confident in their decisions, perceiving these to be similarly intense but less genuine-looking. The findings suggest that senders are capable of voluntarily producing genuine-looking expressions of emotions with minimal effort, especially by mimicking a genuine expression. Implications for research on emotion recognition are discussed.

Brain mechanisms of eye contact during verbal communication predict autistic traits in neurotypical individuals

Atypical eye contact in communication is a common characteristic in autism spectrum disorders. Autistic traits vary along a continuum extending into the neurotypical population. The relation between autistic traits and brain mechanisms underlying spontaneous eye contact during verbal communication remains unexplored. Here, we used simultaneous functional magnetic resonance imaging and eye tracking to investigate this relation in neurotypical people within a naturalistic verbal context. Using multiple regression analyses, we found that brain response in the posterior superior temporal sulcus (pSTS) and its connectivity with the fusiform face area (FFA) during eye contact with a speaker predicted the level of autistic traits measured by Autism-spectrum Quotient (AQ). Further analyses for different AQ subclusters revealed that these two predictors were negatively associated with attention to detail. The relation between FFA–pSTS connectivity and the attention to detail ability was mediated by individuals’ looking preferences for speaker’s eyes. This study identified the role of an individual eye contact pattern in the relation between brain mechanisms underlying natural eye contact during verbal communication and autistic traits in neurotypical people. The findings may help to increase our understanding of the mechanisms of atypical eye contact behavior during natural communication.

Focusing on Mouth Movement to Improve Genuine Smile Recognition

Smiles are the most commonly and frequently used facial expressions by human beings. Some scholars claimed that the low accuracy in recognizing genuine smiles is explained by the perceptual-attentional hypothesis, meaning that observers either did not pay attention to responsible cues or were unable to recognize these cues (usually the Duchenne marker or AU6 displaying as contraction of muscles in eye regions). We investigated whether training (instructing participants to pay attention either to the Duchenne mark or to mouth movement) might help improve the recognition of genuine smiles, including accuracy and confidence. Results indicated that attention to mouth movement improves these people's ability to distinguish between genuine and posed smiles, with nullification of the alternative explanations such as sample distribution and intensity of lip pulling (AU12). The generalization of the conclusion requires further investigations. This study further argues that the perceptual-attentional hypothesis can explain smile genuineness recognition.

Proximity Begins with a Smile, But Which One? Associating Non-duchenne Smiles with Higher Psychological Distance

This study reveals that Duchenne (genuine) and non-Duchenne (non-genuine, polite) smiles are implicitly associated with psychological proximity and distance, respectively. These findings link two extensive research streams from human communication and psychology. Interestingly, extant construal-level theory research suggests the link may work as smiles signaling either a benign situation or politeness, resulting in conflicting predictions for the association between smile type and psychological distance. The current study uses implicit association tests to reveal theoretically and empirically consistent non-Duchenne-smile–distance and Duchenne-smile–proximity associations for all four types of psychological distance: temporal, spatial, social, and hypothetical. Practically, the results suggest several useful applications of non-Duchenne smiles in human communication contexts.

The use of the Duchenne marker and symmetry of the expression in the judgment of smiles in schizophrenia

Research has recurrently shown that individuals with schizophrenia have impairments in emotional facial recognition and this deficit has been associated with aberrant visual scanning of the face. Because human beings have the ability to control the expression of emotion, the communication process becomes more complex. The goal of the current study was to conduct a systematic examination of the response pattern and perceptual-attentional processing in distinguishing smiles with the presence and absence of the Duchenne marker and symmetry and asymmetry of the activation in individuals with schizophrenia. Sixteen individuals diagnosed with schizophrenia and 16 control individuals were asked to judge whether the smiles were really happy or not. Individuals with schizophrenia produced fewer expected responses than controls in judging the symmetric non-Duchenne smile as not really happy. In addition, like their healthy counterparts, individuals with schizophrenia showed difficulty with the judgement of asymmetric Duchenne smiles. In addition to not being as sensitive to the cues, individuals with schizophrenia show differences in their viewing patterns. While the current study does not provide clear links between these viewing patterns and judgment responses, future research should explore other explanations, such as explicit knowledge, for the differences in results.

Hiding true emotions: micro-expressions in eyes retrospectively concealed by mouth movements

When we encounter someone we dislike, we may momentarily display a reflexive disgust expression, only to follow-up with a forced smile and greeting. Our daily lives are replete with a mixture of true and fake expressions. Nevertheless, are these fake expressions really effective at hiding our true emotions? Here we show that brief emotional changes in the eyes (micro-expressions, thought to reflect true emotions) can be successfully concealed by follow-up mouth movements (e.g. a smile). In the same manner as backward masking, mouth movements of a face inhibited conscious detection of all types of micro-expressions in that face, even when viewers paid full attention to the eye region. This masking works only in a backward direction, however, because no disrupting effect was observed when the mouth change preceded the eye change. These results provide scientific evidence for everyday behaviours like smiling to dissemble, and further clarify a major reason for the difficulty we face in discriminating genuine from fake emotional expressions.

The Confusion of Fear and Surprise: A Developmental Study of the Perceptual-Attentional Limitation Hypothesis Using Eye Movements

The goal of the present study was to test the Perceptual-Attentional Limitation Hypothesis in children and adults by manipulating the distinctiveness between expressions and recording eye movements. Children 3-5 and 9-11 years old as well as adults were presented pairs of expressions and required to identify a target emotion. Children 3-5 years old were less accurate than those 9-11 years old and adults. All children viewed pictures longer than adults but did not spend more time attending to the relevant cues. For all participants, accuracy for the recognition of fear was lower than for surprise when the distinctive cue was in the brow only. They also took longer and spent more time in both the mouth and brow zones than when a cue was in the mouth or both areas. Adults and children 9-11 years old made more comparisons between the expressions when fear comprised a single distinctive cue in the brow than when the distinctive cue was in the mouth only or when both cues were present. Children 3-5 years old made more comparisons for brow only than both. The results of the present study extend on the Perceptual-Attentional Limitation Hypothesis showing an importance of both decoder and stimuli, and an interaction between decoder and stimuli characteristics.

Confusion of fear and surprise: a test of the perceptual-attentional limitation hypothesis with eye movement monitoring

Of the basic emotional facial expressions, fear is typically less accurately recognised as a result of being confused with surprise. According to the perceptual-attentional limitation hypothesis, the difficulty in recognising fear could be attributed to the similar visual configuration with surprise. In effect, they share more muscle movements than they possess distinctive ones. The main goal of the current study was to test the perceptual-attentional limitation hypothesis in the recognition of fear and surprise using eye movement recording and by manipulating the distinctiveness between expressions. Results revealed that when the brow lowerer is the only distinctive feature between expressions, accuracy is lower, participants spend more time looking at stimuli and they make more comparisons between expressions than when stimuli include the lip stretcher. These results not only support the perceptual-attentional limitation hypothesis but extend its definition by suggesting that it is not solely the number of distinctive features that is important but also their qualitative value.

Analysis of eye movements in the judgment of enjoyment and non-enjoyment smiles

Enjoyment smiles are more often associated with the simultaneous presence of the Cheek raiser and Lip corner puller action units, and these units' activation is more often symmetric. Research on the judgment of smiles indicated that individuals are sensitive to these types of indices, but it also suggested that their ability to perceive these specific indices might be limited. The goal of the current study was to examine perceptual-attentional processing of smiles by using eye movement recording in a smile judgment task. Participants were presented with three types of smiles: a symmetric Duchenne, a non-Duchenne, and an asymmetric smile. Results revealed that the Duchenne smiles were judged happier than those with characteristics of non-enjoyment. Asymmetric smiles were also judged happier than the non-Duchenne smiles. Participants were as effective in judging the latter smiles as not really happy as they were in judging the symmetric Duchenne smiles as happy. Furthermore, they did not spend more time looking at the eyes or mouth regardless of types of smiles. While participants made more saccades between each side of the face for the asymmetric smiles than the symmetric ones, they judged the asymmetric smiles more often as really happy than not really happy. Thus, processing of these indices do not seem limited to perceptual-attentional difficulties as reflected in viewing behavior.

Susceptibility to emotional contagion for negative emotions improves detection of smile authenticity

A smile is a context-dependent emotional expression. A smiling face can signal the experience of enjoyable emotions, but people can also smile to convince another person that enjoyment is occurring when it is not. For this reason, the ability to discriminate between felt and faked enjoyment expressions is a crucial social skill. Despite its importance, adults show remarkable individual variation in this ability. Revealing the factors responsible for these huge individual differences is a key challenge in this domain. Here we investigated, on a large sample of participants, whether individual differences in smile authenticity recognition are accounted for by differences in the predisposition to experience other people's emotions, i.e., by susceptibility to emotional contagion. Results showed that susceptibility to emotional contagion for negative emotions increased smile authenticity detection, while susceptibility to emotional contagion for positive emotions worsened detection performance, because it leaded to categorize most of the faked smiles as sincere. These findings suggest that susceptibility to emotional contagion plays a key role in complex emotion recognition, and point out the importance of analyzing the tendency to experience other people's positive and negative emotions as separate abilities.