On the interplay between familiarity and emotional expression in face perception

Pupillary Responses to Faces Are Modulated by Familiarity and Rewarding Context

Observing familiar (known, recognisable) and socially relevant (personally important) faces elicits activation in the brain’s reward circuit. Although smiling faces are often used as social rewards in research, it is firstly unclear whether familiarity and social relevance modulate the processing of faces differently, and secondly whether this processing depends on the feedback context, i.e., if it is different when smiles are delivered depending on performance or in the absence of any action (passive viewing). In this preregistered study, we compared pupillary responses to smiling faces differing in subjective familiarity and social relevance. They were displayed in a passive viewing task and in an active task (a speeded visual short-term memory task). The pupils were affected only in the active task and only by subjective familiarity. Contrary to expectations, smaller dilations were observed in response to more familiar faces. Behavioural ratings supported the superior rewarding context of the active task, with higher reward ratings for the game than the passive task. This study offers two major insights. Firstly, familiarity plays a role in the processing of social rewards, as known and unknown faces influence the autonomic responses differently. Secondly, the feedback context is crucial in reward research as positive stimuli are rewarding when they are dependent on performance.

The Effects of Facial Attractiveness and Familiarity on Facial Expression Recognition

The classic theory of face perception holds that the invariant (e.g., identity and race) and variant (e.g., expression) dimensions of face information are independent of one another. Two separate neural systems are involved in face processing. However, the dynamic theory of face perception indicates that these two neural systems interact bidirectionally. Accordingly, by using the emotion categorization task and morph movies task, we investigated the influence of facial attractiveness on facial expression recognition and provided further evidence supporting the dynamic theory of face perception in both the static and dynamic contexts. In addition, this research used familiar celebrities (including actors, television personalities, politicians, and comedians) and explored the role of familiarity in face perception. In two experiments, the participants were asked to assess the expressions of faces with different levels of attractiveness and different levels of familiarity. We found that regardless of being in a static or dynamic face situation, happy expressions on attractive faces can be recognized more quickly, highlighting the advantage of happy expression recognition. Moreover, in static and dynamic familiar face situations, familiarity has a greater impact on expression recognition, and the influence of attraction on expression recognition may be weakened or even unaffected. Our results show that facial attractiveness influences the recognition of facial expressions in both static and dynamic contexts and highlight the importance of familiarity in face perception.

Facial Identity Memory Is Enhanced When Sender's Expression Is Congruent to Perceiver's Experienced Emotion

The role of the social context in facial identity recognition and expression recall was investigated by manipulating the sender's emotional expression and the perceiver's experienced emotion during encoding. A mixed-design with one manipulated between-subjects factor (perceiver's experienced emotion) and two within-subjects factors (change in experienced emotion and sender's emotional expression) was used. Senders' positive and negative expressions were implicitly encoded while perceivers experienced their baseline emotion and then either a positive or a negative emotion. Facial identity recognition was then tested using senders' neutral expressions. Memory for senders previously seen expressing positive or negative emotion was facilitated if the perceiver initially encoded the expression while experiencing a positive or a negative emotion, respectively. Furthermore, perceivers were confident of their decisions. This research provides a more detailed understanding of the social context by exploring how the sender-perceiver interaction affects the memory for the sender.

Startling similarity: Effects of facial self-resemblance and familiarity on the processing of emotional faces

Facial self-resemblance has been associated with positive emotional evaluations, but this effect may be biased by self-face familiarity. Here we report two experiments utilizing startle modulation to investigate how the processing of facial expressions of emotion is affected by subtle resemblance to the self as well as to familiar faces. Participants of the first experiment (I) (N = 39) were presented with morphed faces showing happy, neutral, and fearful expressions which were manipulated to resemble either their own or unknown faces. At SOAs of either 300 ms or 3500–4500 ms after picture onset, startle responses were elicited by binaural bursts of white noise (50 ms, 105 dB), and recorded at the orbicularis oculi via EMG. Manual reaction time was measured in a simple emotion discrimination paradigm. Pictures preceding noise bursts by short SOA inhibited startle (prepulse inhibition, PPI). Both affective modulation and PPI of startle in response to emotional faces was altered by physical similarity to the self. As indexed both by relative facilitation of startle and faster manual responses, self-resemblance apparently induced deeper processing of facial affect, particularly in happy faces. Experiment II (N = 54) produced similar findings using morphs of famous faces, yet showed no impact of mere familiarity on PPI effects (or response time, either). The results are discussed with respect to differential (presumably pre-attentive) effects of self-specific vs. familiar information in face processing.

Infants predict expressers' cooperative behavior through facial expressions

This study investigated infants' ability to use facial expressions to predict the expressers' subsequent cooperative behavior. To explore this problem, Experiment 1 tested 10- and 14-month-olds (N = 16, respectively) by using a violation-of-expectation procedure. In the experiment, all infants were first familiarized with two models, one with a happy facial expression and the other with an angry expression. They were also familiarized with an event in which a duck puppet tried to open a box but failed. During the test phase, infants in the helping condition saw two test scenes; one in which the happy model helped the duck open the box, and the other in which the angry model helped the duck. Infants in the hindering condition saw a test scene in which the happy model hindered the duck and the other test scene in which the angry model hindered the duck. The results demonstrated that both 10- and 14-month-olds looked longer at the angry model than at the happy model in the helping condition, whereas they looked at the happy model as long as the angry model in the hindering condition. Experiment 2 tested 6-month-olds (N = 16) with a slightly modified procedure and found the same tendency as shown by 10- and 14-month-olds. These results suggest that infants as early as at 6 months do not predict that a person with an angry expression will help others. However at the same time, they do not clearly understand the incongruence between happy expressions and hindering behavior. The results were discussed by referring to a negativity bias and human environment in which infants grow up.

Differential heart rate responses to social and monetary reinforcement in women with obesity

Obesity is often accompanied by weight stigmatization; subsequently, individuals with obesity frequently face social rejection. It has been shown that recurrent negative social experiences can alter the perception of social cues. However, the way individuals with obesity process social stimuli is not well understood. This study aims to investigate obesity-related alterations in social compared to nonsocial information processing. Women with obesity (n = 14) and without obesity (n = 14) participated in a social and a monetary incentive delay task in which they anticipated and received positive, negative, and neutral outcomes in the form of faces or money. During the experiment, phasic heart rate changes and reaction times were measured. Women with obesity, compared to lean women, exhibited a stronger differentiation during the anticipation of monetary and social reinforcement, showing slower reaction times to social cues compared to monetary cues. During the outcome processing phase, women with obesity relative to controls demonstrated diminished heart rate responses particularly to negative social outcomes. Interestingly, differences in cardiac responses in participants with obesity were moderated by weight-related teasing experiences. In women with obesity, a higher BMI was associated with blunted cardiac responses to social cues relative to monetary cues only if they reported more emotional pain after weight-related teasing. Our results contribute to a better understanding of social information processing in obesity and give first evidence for the role of negative social experiences in reinforcement processing.

The Facial Expressive Action Stimulus Test. A test battery for the assessment of face memory, face and object perception, configuration processing, and facial expression recognition

There are many ways to assess face perception skills. In this study, we describe a novel task battery FEAST (Facial Expressive Action Stimulus Test) developed to test recognition of identity and expressions of human faces as well as stimulus control categories. The FEAST consists of a neutral and emotional face memory task, a face and shoe identity matching task, a face and house part-to-whole matching task, and a human and animal facial expression matching task. The identity and part-to-whole matching tasks contain both upright and inverted conditions. The results provide reference data of a healthy sample of controls in two age groups for future users of the FEAST.

Familiarity is not notoriety: phenomenological accounts of face recognition

From a phenomenological perspective, faces are perceived differently from objects as their perception always involves the possibility of a relational engagement (Bredlau, 2011). This is especially true for familiar faces, i.e., faces of people with a history of real relational engagements. Similarly, valence of emotional expressions assumes a key role, as they define the sense and direction of this engagement. Following these premises, the aim of the present study is to demonstrate that face recognition is facilitated by at least two variables, familiarity and emotional expression, and that perception of familiar faces is not influenced by orientation. In order to verify this hypothesis, we implemented a 3 × 3 × 2 factorial design, showing 17 healthy subjects three type of faces (unfamiliar, personally familiar, famous) characterized by three different emotional expressions (happy, hungry/sad, neutral) and in two different orientation (upright vs. inverted). We showed every subject a total of 180 faces with the instructions to give a familiarity judgment. Reaction times (RTs) were recorded and we found that the recognition of a face is facilitated by personal familiarity and emotional expression, and that this process is otherwise independent from a cognitive elaboration of stimuli and remains stable despite orientation. These results highlight the need to make a distinction between famous and personally familiar faces when studying face perception and to consider its historical aspects from a phenomenological point of view.

Asymmetric switch-costs and ERPs reveal facial identity dominance over expression

Previous studies on face processing have revealed an asymmetric overlap between identity and expression, as identity is processed irrespective of expression while expression processing partly depends on identity. To investigate whether this relative interaction is caused by dominance of identity over expression, participants performed familiarity and expression judgments during task switching. This paradigm reveals task-set dominance with a paradoxical asymmetric switch-cost (i.e., greater difference between switch and repeat trials when switching toward the dominant task). Event-related potentials (ERPs) were recorded to find the neural signature of the asymmetric cost. As expected, greater switch-cost was shown in the familiarity task with respect to response times, indicating its dominance over the expression task. Moreover, a left-sided ERP correlate of this effect was observed at the level of the frontal N2 component, interpreted as an index of modulations in endogenous executive control. Altogether, these results confirm the overlap between identity and expression during face processing and further indicate their relative dominance.

Flexible and inflexible task sets: asymmetric interference when switching between emotional expression, sex, and age classification of perceived faces

The present study investigated whether the processing characteristics of categorizing emotional facial expressions are different from those of categorizing facial age and sex information. Given that emotions change rapidly, it was hypothesized that processing facial expressions involves a more flexible task set that causes less between-task interference than the task sets involved in processing age or sex of a face. Participants switched between three tasks: categorizing a face as looking happy or angry (emotion task), young or old (age task), and male or female (sex task). Interference between tasks was measured by global interference and response interference. Both measures revealed patterns of asymmetric interference. Global between-task interference was reduced when a task was mixed with the emotion task. Response interference, as measured by congruency effects, was larger for the emotion task than for the nonemotional tasks. The results support the idea that processing emotional facial expression constitutes a more flexible task set that causes less interference (i.e., task-set "inertia") than processing the age or sex of a face.

Familiar smiling faces in Alzheimer's disease: understanding the positivity-related recognition bias

Recent research has revealed a recognition bias favoring positive faces and other stimuli in older compared to younger adults. However, it is yet unclear whether this bias reflects an age-related preference for positive emotional stimuli, or an affirmatory bias used to compensate for episodic memory deficits. To follow up this point, the present study examined recognition of emotional faces and current mood state in patients with mild Alzheimer disease (AD) and healthy controls. Expecting lower overall memory performance, more negative and less positive mood in AD patients, the critical question was whether the positivity-related recognition bias would be increased compared to cognitively unimpaired controls. Eighteen AD patients and 18 healthy controls studied happy, neutral, and angry faces, which in a subsequent recognition task were intermixed with 50% distracter faces. As expected, the patient group showed reduced memory performance, along with a less positive and more negative mood. The recognition bias for positive faces persisted. This pattern supports the view that the positivity-induced recognition bias represents a compensatory, gist-based memory process that is applied when item-based recognition fails.

Covert face recognition relies on affective valence in congenital prosopagnosia

Dominant accounts of covert recognition in prosopagnosia assume subthreshold activation of face representations created prior to onset of the disorder. Yet, such accounts cannot explain covert recognition in congenital prosopagnosia, where the impairment is present from birth. Alternatively, covert recognition may rely on affective valence, yet no study has explored this possibility. The current study addressed this issue in 3 individuals with congenital prosopagnosia, using measures of the scanpath to indicate recognition. Participants were asked to memorize 30 faces paired with descriptions of aggressive, nice, or neutral behaviours. In a later recognition test, eye movements were monitored while participants discriminated studied from novel faces. Sampling was reduced for studied--nice compared to studied--aggressive faces, and performance for studied--neutral and novel faces fell between these two conditions. This pattern of findings suggests that (a) positive emotion can facilitate processing in prosopagnosia, and (b) covert recognition may rely on emotional valence rather than familiarity.