Action value calculations in social context from infancy.

Infants adaptively modulate their social behaviours, such as gaze-following, to social context. We propose that such modulations are based on infants' social decision-making, to achieve the most valuable outcome. We propose an 'action value calculator model', which formulates the cognitive mechanisms underlying, and the development of, the decision-making process during interactions.

Social reward anticipation in infants as revealed by event-related potentials.

Infants engage in gaze interaction from the early stage of life. Emerging studies suggest that infants may expect social reward of shared attention before looking to the same object with another person. However, it was unknown about the neural responses during the anticipation of social rewards before shared attention in infants. We tested infants' reward anticipations in the gaze cueing situation measured by event-related potentials in the social association learning task. Six- to ten-month-old infants (N = 20) repeatedly observed that a female predictively looked toward the animation position (valid condition) or another female looking away from the animation (invalid condition). It was posited that infants could learn associations between female faces and the event of shared attention. The results showed that the stimulus preceding negativity which reflects reward anticipation before the animation presentation was elicited in the second half of the learning phases in the valid condition. Additionally, after the presentation of the face, N290 was greater in the second half of the learning phase than in the first half in the valid condition. These results suggest that infants can anticipate social reward from gaze cues, and learning the gaze cueing validity may affect not only reward anticipation but face perception.

Physiological arousal explains infant gaze following in various social contexts.

Gaze following (GF) is fundamental to central aspects of human sociocognitive development, such as acquiring language and cultural learning. Studies have shown that infant GF is not a simple reflexive orientation to an adult's eye movement. By contrast, infants adaptively modulate GF behaviour depending on the social context. However, arguably, the neurophysiological mechanisms underlying contextual modulation of GF remain somewhat unexplored. In this study, we tested the proposition about whether the contextual modulation of infant GF is mediated by the infant's heart rate (HR), which indicates the infant's physiological arousal. Forty-one 6- to 9-month-old infants participated in this study, and infants observed either a reliable face, which looked towards the location of an object, or an unreliable face, which looked away from the location of an object. Thereafter, the infants watched a video of the same model making eye contact or not making any ostensive signals, before shifting their gaze towards one of the two objects. We revealed that reliability and eye contact acted independently to increase HR, which then fully mediates the effects of these social cues on the frequency of GF. Results suggest that each social cue independently enhances physiological arousal, which then accumulatively predicts the likelihood of infant GF behaviour.

Pupil dilation predicts modulation of direct gaze on action value calculations.

Perceiving direct gaze facilitates social cognition and behaviour. We hypothesized that direct gaze modulates decision-making, particularly calculations of action values. To test our hypothesis, we used the reinforcement learning paradigm in situations with or without direct gaze. Forty adults were recruited and participated in pupil size measurements and a two-armed bandit task. The task was conducted with 70% and 30% reward probabilities for each option. During the task, a female showing the Direct Gaze (DG) or Closed Eyes (CE) condition was presented from the start of each trial. The results showed that behavioural bias to choices with 70% reward probability increased more in the DG condition than in the CE condition and the expected reward value. This bias to choices with 70% reward in the DG condition was predicted by pupil dilation to DG. These results suggest that participants over-evaluated the expected reward value in the DG condition, and this DG effect may be related to subjective expectations of rewarding events indexed by pupil dilations. It is considered that perceiving direct gaze is a driver of reward expectations that modulate action value calculations and then cognitive processing and behaviours are facilitated.

Affective priming enhances gaze cueing effect.

Other's gaze direction triggers a reflexive shift of attention known as the gaze cueing effect. Fearful facial expressions are further reported to enhance the gaze cueing effect, but it remains unclear whether this facilitative effect is specific to gaze cues or the result of more general increase in attentional resources resulting from affective arousal. We examined the effects of affective priming on the cueing effects of gaze and arrow stimuli in the Posner cueing task. Participants were primed with two types of briefly presented affective stimuli (neutral, threatening), and the target location was cued either by an arrow or a gaze cue in a neutral face. Gaze cues were preceded by the same face with its eyes closed or directed to the viewer. Study 1 (n = 26) assessed the cueing effect using manual key press, and Study 2 (n = 30) employed gaze-contingent eye tracking techniques to assess the cueing effect using time to first fixate the cued target location. Both studies found that threatening priming significantly enhanced the cueing effects of eye gaze but not arrow stimuli. The results therefore suggest that affective priming does not facilitate general attentional orienting, but the facilitation is more specific to social cues such as eye gaze. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Cultural influences on face scanning are consistent across infancy and adulthood.

The emergence of cultural differences in face scanning is thought to be shaped by social experience. However, previous studies mainly investigated eye movements of adults and little is known about early development. The current study recorded eye movements of British and Japanese infants (aged 10 and 16 months) and adults, who were presented with static and dynamic faces on screen. Cultural differences were observed across all age groups, with British participants exhibiting more mouth scanning, and Japanese individuals showing increased central face (nose) scanning for dynamic stimuli. Age-related influences independent of culture were also revealed, with a shift from eye to mouth scanning between 10 and 16 months, while adults distributed their gaze more flexibly. Against our prediction, no age-related increases in cultural differences were observed, suggesting the possibility that cultural differences are largely manifest by 10 months of age. Overall, the findings suggest that individuals adopt visual strategies in line with their cultural background from early in infancy, pointing to the development of a highly adaptive face processing system that is shaped by early sociocultural experience.

Learning Process of Gaze Following: Computational Modeling Based on Reinforcement Learning.

Many studies have explored factors which influence gaze-following behavior of young infants. However, the results of empirical studies were inconsistent, and the mechanism underlying the contextual modulation of gaze following remains unclear. In order to provide valuable insight into the mechanisms underlying gaze following, we conducted computational modeling using Q-learning algorithm and simulated the learning process of infant gaze following to suggest a feasible model. In Experiment 1, we simulated how communicative cues and infant internal states affect the learning process of gaze following. The simulation indicated that the model in which communicative cues enhance infant internal states is the most feasible to explain the infant learning process. In Experiment 2, we simulated how individual differences in motivation for communication affect the learning process. The results showed that low motivation for communication can delay the learning process and decrease the frequency of gaze following. These simulations suggest that communicative cues may enhance infants' internal states and promote the development of gaze following. Also, initial social motivation may affect the learning process of social behaviors in the long term.

Culture modulates face scanning during dyadic social interactions.

Recent studies have revealed significant cultural modulations on face scanning strategies, thereby challenging the notion of universality in face perception. Current findings are based on screen-based paradigms, which offer high degrees of experimental control, but lack critical characteristics common to social interactions (e.g., social presence, dynamic visual saliency), and complementary approaches are required. The current study used head-mounted eye tracking techniques to investigate the visual strategies for face scanning in British/Irish (in the UK) and Japanese adults (in Japan) who were engaged in dyadic social interactions with a local research assistant. We developed novel computational data pre-processing tools and data-driven analysis techniques based on Monte Carlo permutation testing. The results revealed significant cultural differences in face scanning during social interactions for the first time, with British/Irish participants showing increased mouth scanning and the Japanese group engaging in greater eye and central face looking. Both cultural groups further showed more face orienting during periods of listening relative to speaking, and during the introduction task compared to a storytelling game, thereby replicating previous studies testing Western populations. Altogether, these findings point to the significant role of postnatal social experience in specialised face perception and highlight the adaptive nature of the face processing system.

Effects of attentional behaviours on infant visual preferences and object choice.

Many developmental studies have examined the effects of joint attention. However, it has been difficult to compare effects of initiating joint attention and responding to joint attention in infants. Here, we compared the effects of initiating joint attention and responding joint attention on object information processing, object preference, and facial preferences in infants. Thirty-seven infants (10 to 12 months of age) were shown stimuli in which a female gazed towards or away from an object. Participants were assigned to initiating joint attention condition or responding joint attention condition. Results suggest that initiating joint attention promoted object information processing, whereas responding joint attention did not. Both joint attention conditions affected the facial preference for the person who engaged joint attention. In addition, after initiating joint attention, infants chose objects gazed by other person more often than after responding joint attention. It appears that attentional behaviours that precede the perception of certain stimuli affect infants' cognitive responses to those stimuli.

Physiological arousal predicts gaze following in infants.

According to the natural pedagogy theory, infant gaze following is based on an understanding of the communicative intent of specific ostensive cues. However, it has remained unclear how eye contact affects this understanding and why it induces gaze following behaviour. In this study, we examined infant arousal in different gaze following contexts and whether arousal levels during eye contact predict gaze following. Twenty-five infants, ages 9-10 months participated in this study. They watched a video of an actress gazing towards one of two objects and then either looking directly into the camera to make eye contact or not showing any communicative intent. We found that eye contact led to an elevation in the infants' heart rates (HRs) and that HR during eye contact was predictive of later gaze following. Furthermore, increases in HR predicted gaze following whether it was accompanied by communicative cues or not. These findings suggest that infant gaze following behaviour is associated with both communicative cues and physiological arousal.

Observing Others' Gaze Direction Affects Infants' Preference for Looking at Gazing- or Gazed-at Faces.

Eye gaze is an important signal in social interactions, and it plays an important role to understand what others looking in joint attention (JA) situations. JA has been examined in situations involving two people gazing at objects; however, ecologically, infants observe not only faces that gaze at objects but also those that gaze at other people. Here, we examined how eye gaze directed toward another face affect face preferences in infants. A total of 19 children were observed during a JA situation and a no-JA situation. In the JA situation, an adult face in the central position of the screen shifted her gaze to look at another adult face at a lateral position on the screen. However, during the no JA situation, the central face shifted her eye gaze away from the adult face presented on the screen. At test, for the centrally presented faces, infant looking times were longer at faces in the no JA condition. At test, for the laterally presented faces, looking times were longer at the faces in the JA condition. Thus, the adult's eye gaze biased the duration of the gaze of the infants at either the central faces or the lateral-cued faces in the preferential looking tests. These results suggest that 10-month-old infants may interpret adult gazing behavior and that this can affect the gazing behavior of infants.

Autistic Traits Affect P300 Response to Unexpected Events, regardless of Mental State Inferences.

Limited use of contextual information has been suggested as a way of understanding cognition in people with autism spectrum disorder (ASD). However, it has also been argued that individuals with ASD may have difficulties inferring others' mental states. Here, we examined how individuals with different levels of autistic traits respond to contextual deviations by measuring event-related potentials that reflect context usage. The Autism Spectrum Quotient (AQ) was used to quantify autistic-like traits in 28 university students, and 19 participants were defined as Low or High AQ groups. To additionally examine inferences about mental state, two belief conditions (with or without false belief) were included. Participants read short stories in which the final sentence included either an expected or an unexpected word and rated the word's degree of deviation from expectation. P300 waveform analysis revealed that unexpected words were associated with larger P300 waveforms for the Low AQ group, but smaller P300 responses in the High AQ group. Additionally, AQ social skill subscores were positively correlated with evaluation times in the Unexpected condition, whether a character's belief was false or not. This suggests that autistic traits can affect responses to unexpected events, possibly because of decreased availability of context information.

Social information affects adults' evaluation of fairness in distributions: An ERP approach.

The sense of fairness has been observed in early infancy. Because many studies of fairness in adults have used economic games such as the Ultimatum Game, it has been difficult to compare fairness between adults and infants. Further, recent studies have suggested that social information about actors who behave fairly or unfairly may influence the judgement of fairness in infants. Therefore, to compare the sense of fairness between infants and adults, the study using paradigm in infant research is required. We examined how social information about two characters, either prosocial or antisocial, affects the event-related potential response (ERP) to fair or unfair resource distributions in adults. In the habituation phase, participants were informed about characters' social information through their actions. One character then distributed resources fairly or unfairly, and ERP was measured at the end of the distribution. Data from eighteen adult participants were analysed. A significant interaction of social information and fairness was found for late positive potential (LPP), but a post-hoc t test revealed a significant difference between fair and unfair conditions only for actions of the antisocial character. We found that LPP can reflect the sense of fairness affected by social information. Comparison with infant studies suggests that the sense of fairness may change during development.