Predictive social perception: Towards a unifying framework from action observation to person knowledge

Facial misfits accelerate stereotype-based associative learning

Counterstereotypes challenge the deleterious effects that gender-typed beliefs exert on people's occupational aspirations and lifestyle choices. Surprisingly, however, the critical issue of how readily unexpected person-related knowledge can be acquired remains poorly understood. Accordingly, in two experiments in which the facial appearance of targets was varied to manipulate goodness-of-stereotype-fit (i.e., high vs. low femininity/masculinity), here we used a probabilistic selection task to probe the rate at which counter-stereotypic and stereotypic individuals can be learned. Whether occupational (Expt. 1) or trait-related (Expt. 2) gender stereotypes were explored, a computational analysis yielded consistent results. Underscoring the potency of surprising information (i.e., facial misfits), knowledge acquisition was accelerated for unexpected compared to expected persons, both in counter-stereotypic and stereotypic learning contexts. These findings affirm predictive accounts of social perception and speak to the optimal characteristics of interventions designed to reduce stereotyping outside the laboratory.

Observers predict actions from facial emotional expressions during real-time social interactions

In face-to-face social interactions, emotional expressions provide insights into the mental state of an interactive partner. This information can be crucial to infer action intentions and react towards another person's actions. Here we investigate how facial emotional expressions impact subjective experience and physiological and behavioral responses to social actions during real-time interactions. Thirty-two participants interacted with virtual agents while fully immersed in Virtual Reality. Agents displayed an angry or happy facial expression before they directed an appetitive (fist bump) or aversive (punch) social action towards the participant. Participants responded to these actions, either by reciprocating the fist bump or by defending the punch. For all interactions, subjective experience was measured using ratings. In addition, physiological responses (electrodermal activity, electrocardiogram) and participants' response times were recorded. Aversive actions were judged to be more arousing and less pleasant relative to appetitive actions. In addition, angry expressions increased heart rate relative to happy expressions. Crucially, interaction effects between facial emotional expression and action were observed. Angry expressions reduced pleasantness stronger for appetitive compared to aversive actions. Furthermore, skin conductance responses to aversive actions were increased for happy compared to angry expressions and reaction times were faster to aversive compared to appetitive actions when agents showed an angry expression. These results indicate that observers used facial emotional expression to generate expectations for particular actions. Consequently, the present study demonstrates that observers integrate information from facial emotional expressions with actions during social interactions.

People can reliably detect action changes and goal changes during naturalistic perception

As a part of ongoing perception, the human cognitive system segments others' activities into discrete episodes (event segmentation). Although prior research has shown that this process is likely related to changes in an actor's actions and goals, it has not yet been determined whether untrained observers can reliably identify action and goal changes as naturalistic activities unfold, or whether the changes they identify are tied to visual features of the activity (e.g., the beginnings and ends of object interactions). This study addressed these questions by examining untrained participants' identification of action changes, goal changes, and event boundaries while watching videos of everyday activities that were presented in both first-person and third-person perspectives. We found that untrained observers can identify goal changes and action changes consistently, and these changes are not explained by visual change and the onsets or offsets of contact with objects. Moreover, the action and goal changes identified by untrained observers were associated with event boundaries, even after accounting for objective visual features of the videos. These findings suggest that people can identify action and goal changes consistently and with high agreement, that they do so by using sensory information flexibly, and that the action and goal changes they identify may contribute to event segmentation.

Motivation and prediction-driven processing of social memoranda

Social semantic memory guides many aspects of behavior. Individuals rely on acquired and inferred knowledge about personal characteristics and group membership to predict the behavior and character of social targets. These predictions then determine the expectations from, the behavior in, and the interpretations of social interactions. According to predictive processing accounts, mnemonic and attentional mechanisms should enhance the processing of prediction-violating events. However, empirical findings suggest that prediction-consistent social events are often better remembered. This mini-review integrates recent evidence from social and non-social memory research to highlight the role of motivation in explaining these discrepancies. A particular emphasis is given to the continuous nature of prediction-(in)consistency, the epistemic tendency of perceivers to maintain or update their knowledge, and the dynamic influences of motivation on multiple steps in prediction-driven social memory. The suggested framework provides a coherent outlook of existing work and offers promising future directions to better understand the ebb and flow of social memoranda.

Neural representations of situations and mental states are composed of sums of representations of the actions they afford

Human behavior depends on both internal and external factors. Internally, people's mental states motivate and govern their behavior. Externally, one's situation constrains which actions are appropriate or possible. To predict others' behavior, one must understand the influences of mental states and situations on actions. On this basis, we hypothesize that people represent situations and states in terms of associated actions. To test this, we use functional neuroimaging to estimate neural activity patterns associated with situations, mental states, and actions. We compute sums of the action patterns, weighted by how often each action occurs in each situation and state. We find that these summed action patterns reconstructed the corresponding situation and state patterns. These results suggest that neural representations of situations and mental states are composed of sums of their action affordances. Summed action representations thus offer a biological mechanism by which people can predict actions given internal and external factors.

Augmented action observation: Theory and practical applications in sensorimotor rehabilitation

Sensory feedback is a fundamental aspect of effective motor learning in sport and clinical contexts. One way to provide this is through sensory augmentation, where extrinsic sensory information are associated with, and modulated by, movement. Traditionally, sensory augmentation has been used as an online strategy, where feedback is provided during physical execution of an action. In this article, we argue that action observation can be an additional effective channel to provide augmented feedback, which would be complementary to other, more traditional, motor learning and sensory augmentation strategies. Given these similarities between observing and executing an action, action observation could be used when physical training is difficult or not feasible, for example during immobilization or during the initial stages of a rehabilitation protocol when peripheral fatigue is a common issue. We review the benefits of observational learning and preliminary evidence for the effectiveness of using augmented action observation to improve learning. We also highlight current knowledge gaps which make the transition from laboratory to practical contexts difficult. Finally, we highlight the key areas of focus for future research.

Configuration of the action observation network depends on the goals of the observer

Observing the actions of others engages a core action observation network (AON) that includes the bilateral inferior frontal cortex (IFC), posterior superior temporal sulcus (pSTS) and inferior parietal lobule (IPL) (Caspers et al., 2010). Each region in the AON has functional properties that are heterogeneous and include representing the perceptual properties of action, predicting action outcomes and making inferences as to the goals of the actor. Critically, recent evidence shows that neural representations within the pSTS are sharpened when attending to the kinematics of the actor, such that the top-down guided attention reshapes underlying neural representations. In this study we evaluate how attention alters network connectivity within the AON as a system. Cues directed participant's attention to the goal, kinematics, or identity depicted in short action animations while brain responses were measured by fMRI. We identified those parcels within the AON with functional connectivity modulated by task. Results show that connectivity between the right pSTS and right IFC, and bilateral extended STS (STS+) were modulated during action observation such that connections were strengthened when the participant was attending to the action than goal. This finding is contrasted by the univariate results, which no univariate modulations in these brain regions except for right IFC. Using the functional networks defined by Yeo et al. (2011), we identified the parcels that are modulated by the attention to consist mainly of the fronto-parietal control network and default mode networks. These results are consistent with models of top-down feedback from executive system in the IFC to pSTS and implicates a right lateralized dual pathway model for action observation when focused on whole-body kinematics.

Predicting others' actions from their social contexts

Contextual cues have been shown to inform our understanding and predictions of others' actions. In this study, we tested whether observers' predictions about unfolding actions depend upon the social context in which they occur. Across five experiments, we showed participants videos of an actor walking toward a piece of furniture either with (joint context) or without (solo context) a partner standing by it. We found greater predictive bias, indicative of stronger action expectations when videos contained a second actor (Experiment 1), even when the solo condition had a perceptually-matched control object in place of the actor (Experiment 2). Critically, belief manipulations about the actions the walking actor would perform suppressed the difference between social context conditions when the manipulation specified an action possible in both contexts (Experiment 5) but not when the action was one that would be difficult without a partner (Experiment 4). Interestingly, the social context effect persisted when the belief manipulation specified an unlikely action given the depicted scene (Experiment 3). These findings provide novel evidence that kinematically-identical actions can elicit different predictions depending on the social context in which they occur.

Functional role of the theory of mind network in integrating mentalistic prior information with action kinematics during action observation

Inferring intentions from verbal and nonverbal human behaviour is critical for everyday social life. Here, we combined Transcranial Magnetic Stimulation (TMS) with a behavioural priming paradigm to test whether key nodes of the Theory of Mind network (ToMn) contribute to understanding others' intentions by integrating prior knowledge about an agent with the observed action kinematics. We used a modified version of the Faked-Action Discrimination Task (FAD), a forced-choice paradigm in which participants watch videos of actors lifting a cube and judge whether the actors are trying to deceive them concerning the weight of the cube. Videos could be preceded or not by verbal description (prior) about the agent's truthful or deceitful intent. We applied single pulse TMS over three key nodes of the ToMn, namely dorsomedial prefrontal cortex (dmPFC), right posterior superior temporal sulcus (pSTS) and right temporo-parietal junction (rTPJ). Sham-TMS served as a control (baseline) condition. Following sham or rTPJ stimulation, we observed no consistent influence of priors on FAD performance. In contrast, following dmPFC stimulation, and to a lesser extent pSTS stimulation, truthful and deceitful actions were perceived as more deceptive only when the prior suggested a dishonest intention. These findings highlight a functional role of dmPFC and pSTS in coupling prior knowledge about deceptive intents with observed action kinematics in order to judge faked actions. Our study provides causal evidence that fronto-temporal nodes of the ToMn are functionally relevant to mental state inference during action observation.

Vicarious touch: Overlapping neural patterns between seeing and feeling touch

Simulation theories propose that vicarious touch arises when seeing someone else being touched triggers corresponding representations of being touched. Prior electroencephalography (EEG) findings show that seeing touch modulates both early and late somatosensory responses (measured with or without direct tactile stimulation). Functional Magnetic Resonance Imaging (fMRI) studies have shown that seeing touch increases somatosensory cortical activation. These findings have been taken to suggest that when we see someone being touched, we simulate that touch in our sensory systems. The somatosensory overlap when seeing and feeling touch differs between individuals, potentially underpinning variation in vicarious touch experiences. Increases in amplitude (EEG) or cerebral blood flow response (fMRI), however, are limited in that they cannot test for the information contained in the neural signal: seeing touch may not activate the same information as feeling touch. Here, we use time-resolved multivariate pattern analysis on whole-brain EEG data from people with and without vicarious touch experiences to test whether seen touch evokes overlapping neural representations with the first-hand experience of touch. Participants felt touch to the fingers (tactile trials) or watched carefully matched videos of touch to another person's fingers (visual trials). In both groups, EEG was sufficiently sensitive to allow decoding of touch location (little finger vs. thumb) on tactile trials. However, only in individuals who reported feeling touch when watching videos of touch could a classifier trained on tactile trials distinguish touch location on visual trials. This demonstrates that, for people who experience vicarious touch, there is overlap in the information about touch location held in the neural patterns when seeing and feeling touch. The timecourse of this overlap implies that seeing touch evokes similar representations to later stages of tactile processing. Therefore, while simulation may underlie vicarious tactile sensations, our findings suggest this involves an abstracted representation of directly felt touch.

How unexpected events are processed in theory of mind regions: A conceptual replication

Recent research in social neuroscience has postulated that Theory of Mind (ToM) regions play a role in processing social prediction error (PE: the difference between what was expected and what was observed). Here, we tested whether PE signal depends on the type of prior information people use to make predictions - an agent's prior mental states (e.g., beliefs, desires, preferences) or an agent's prior behavior - as well as the type of information that confirms or violates such predictions. That is, does prior information about mental states (versus behavior) afford stronger predictions about an agent's subsequent mental states or behaviors? Additionally, when information about an agent's prior mental states or behavior is available, is PE signal strongest when information about an agent's subsequent mental state (vs behavior) is revealed? In line with prior research, results suggest that DMPFC, LTPJ, and RTPJ are recruited more for unexpected than expected outcomes. However, PE signal does not seem to discriminate on the basis of prior or outcome information type. These findings suggest that ToM regions may flexibly incorporate any available information to make predictions about, monitor, and perhaps explain, inconsistencies in social agents.

Predictive neural representations of naturalistic dynamic input

Adaptive behavior such as social interaction requires our brain to predict unfolding external dynamics. While theories assume such dynamic prediction, empirical evidence is limited to static snapshots and indirect consequences of predictions. We present a dynamic extension to representational similarity analysis that uses temporally variable models to capture neural representations of unfolding events. We applied this approach to source-reconstructed magnetoencephalography (MEG) data of healthy human subjects and demonstrate both lagged and predictive neural representations of observed actions. Predictive representations exhibit a hierarchical pattern, such that high-level abstract stimulus features are predicted earlier in time, while low-level visual features are predicted closer in time to the actual sensory input. By quantifying the temporal forecast window of the brain, this approach allows investigating predictive processing of our dynamic world. It can be applied to other naturalistic stimuli (e.g., film, soundscapes, music, motor planning/execution, social interaction) and any biosignal with high temporal resolution.

Prompting vegetable purchases in the supermarket by an affordance nudge: Examining effectiveness and appreciation in a set of field experiments

The supermarket is a promising location for stimulating healthier food choices by nudging interventions. However, nudging healthy food choices in the supermarket has shown weak effects to date. The present research introduces a new nudge based on the concept of affordances - i.e., an animated character - that invites interaction with healthy food products and examines its effectiveness and appreciation in a supermarket context. We present findings of a series of three studies. In Study 1, evaluations of the new nudge were collected, revealing that the nudge was appreciated. In Studies 2 and 3, field experiments were conducted to test the nudge's effect on vegetable purchases in a real-life supermarket. Study 3 demonstrated that vegetable purchases increased significantly (up to 17%) when the affordance nudge was placed on the vegetable shelves. Furthermore, customers appreciated the nudge and its potential for implementation. Taken together, this set of studies presents compelling findings illustrating the potential of the affordance nudge for increasing healthy choices in the supermarket.

Guns Are Not Faster to Enter Awareness After Seeing a Black Face: Absence of Race-Priming in a Gun/Tool Task During Continuous Flash Suppression

In the Weapon Identification Task (WIT), Black faces prime the identification of guns compared with tools. We measured race-induced changes in visual awareness of guns and tools using continuous flash suppression (CFS). Eighty-four participants, primed with Black or Asian faces, indicated the location of a gun or tool target that was temporarily rendered invisible through CFS, which provides a sensitive measure of effects on early visual processing. The same participants also completed a standard (non-CFS) WIT. We replicated the standard race-priming effect in the WIT. In the CFS task, Black and Asian primes did not affect the time guns and tools needed to enter awareness. Thus, race priming does not alter early visual processing but does change the identification of guns and tools. This confirms that race-priming originates from later post-perceptual memory- or response-related processing.

The power of the unexpected: Prediction errors enhance stereotype-based learning

Stereotyping is a ubiquitous feature of social cognition, yet surprisingly little is known about how group-related beliefs influence the acquisition of person knowledge. Accordingly, in combination with computational modeling (i.e., Reinforcement Learning Drift Diffusion Model analysis), here we used a probabilistic selection task to explore the extent to which gender stereotypes impact instrumental learning. Several theoretically interesting effects were observed. First, reflecting the impact of cultural socialization on person construal, an expectancy-based preference for stereotype-consistent (vs. stereotype-inconsistent) responses was observed. Second, underscoring the potency of unexpected information, learning rates were faster for counter-stereotypic compared to stereotypic individuals, both for negative and positive prediction errors. Collectively, these findings are consistent with predictive accounts of social perception and have implications for the conditions under which stereotyping can potentially be reduced.

Expectations of efficient actions bias social perception: a pre-registered online replication

Humans take a teleological stance when observing others' actions, interpreting them as intentional and goal directed. In predictive processing accounts of social perception, this teleological stance would be mediated by a perceptual prediction of an ideal energy-efficient reference trajectory with which a rational actor would achieve their goals within the current environmental constraints. Hudson and colleagues (2018 Proc. R. Soc. B 285, 20180638. (doi:10.1098/rspb.2018.0638)) tested this hypothesis in a series of experiments in which participants reported the perceived disappearance points of hands reaching for objects. They found that these judgements were biased towards the expected efficient reference trajectories. Observed straight reaches were reported higher when an obstacle needed to be overcome than if the path was clear. By contrast, unnecessarily high reaches over empty space were perceptually flattened. Moreover, these perceptual biases increased the more the environmental constraints and expected action trajectories were explicitly processed. These findings provide an important advance to our understanding of the mechanisms underlying social perception. The current replication tests the robustness of these findings and whether they uphold in an online setting.

Exploring the Representational Structure of Trait Knowledge Using Perceived Similarity Judgments

A large body of past work has sought to identify the underlying dimensions that capture our trait knowledge of other people. However, the importance of particular traits in determining our overall impressions of others is not well understood, and different traits may be fundamental for impressions of famous versus unfamiliar people. For instance, we may focus on competence when evaluating a famous person, but on trustworthiness when evaluating a stranger. To examine the structure of overall impressions of famous people and of unfamiliar people, we probed the contributions of 13 different trait judgments to perceived similarity judgments. We found that different sets of traits best predicted perceived similarity between famous people versus between unfamiliar people; however, the relationship between each trait and perceived similarity generalized to some extent from famous people to unfamiliar people, suggesting a degree of overlap in the structure of overall impressions.

The promises and pitfalls of functional magnetic resonance imaging hyperscanning for social interaction research

Social neuroscience combines tools and perspectives from social psychology and neuroscience to understand how people interact with their social world. Here we discuss a relatively new method-hyperscanning-to study real-time, interactive social interactions using functional magnetic resonance imaging (fMRI). We highlight three contributions that fMRI hyperscanning makes to the study of the social mind: (1) Naturalism: it shifts the focus from tightly-controlled stimuli to more naturalistic social interactions; (2) Multi-person Dynamics: it shifts the focus from individuals as the unit of analysis to dyads and groups; and (3) Neural Resolution: fMRI hyperscanning captures high-resolution neural patterns and dynamics across the whole brain, unlike other neuroimaging hyperscanning methods (e.g., electroencephalogram, functional near-infrared spectroscopy). Finally, we describe the practical considerations and challenges that fMRI hyperscanning researchers must navigate. We hope researchers will harness this powerful new paradigm to address pressing questions in today's society.

The reciprocal relationship between episodic memory and future thinking: How the outcome of predictions is subsequently remembered

Evidence suggests that memory is involved in making simulations and predictions about the future (i.e., future thinking), but less work has examined how the outcome of those predictions (whether events play out as predicted or expected) subsequently affects episodic memory. In this investigation, we examine whether memory is better for outcomes that are consistent with predictions, or whether memory is enhanced for outcomes that are inconsistent with predictions, after the predicted event occurs. In this experiment, participants learned a core trait associated with social targets (e.g., high in extroversion), before making predictions about behaviors targets would perform. Participants then were shown behaviors the social targets actually performed (i.e., prediction outcome), which was either consistent or inconsistent with predictions. After that, participants completed a memory test (recognition; recall) for the prediction outcomes. For recognition, the results revealed better memory for outcomes that were consistent with traits associated with targets (i.e., trait-consistent outcomes), compared to outcomes that were inconsistent (i.e., trait-inconsistent outcomes). Finding a memory advantage for trait-consistent outcomes suggests that outcomes that are in line with the contents of memory (e.g., what one knows; schemas) are more readily remembered than those that are inconsistent with memory, which may reflect an adaptive memory process. For recall, memory did not differ between trait-consistent and trait-inconsistent outcomes. Altogether, the results of this experiment advance understanding of the reciprocal relationship between episodic memory and future thinking and show that outcome of predictions has an influence on subsequent episodic memory, at least as measured by recognition.

Human but not robotic gaze facilitates action prediction

Do people ascribe intentions to humanoid robots as they would to humans or non-human-like animated objects? In six experiments, we compared people’s ability to extract non-mentalistic (i.e., where an agent is looking) and mentalistic (i.e., what an agent is looking at; what an agent is going to do) information from gaze and directional cues performed by humans, human-like robots, and a non-human-like object. People were faster to infer the mental content of human agents compared to robotic agents. Furthermore, although the absence of differences in control conditions rules out the use of non-mentalizing strategies, the human-like appearance of non-human agents may engage mentalizing processes to solve the task. Overall, results suggest that human-like robotic actions may be processed differently from humans’ and objects’ behavior. These findings inform our understanding of the relevance of an object’s physical features in triggering mentalizing abilities and its relevance for human–robot interaction.

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People differently ascribe mental content to human-like and non-human-like agents

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A human-like shape may automatically engage mentalizing processes

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Human actions are interpreted faster than non-human actions

The Role of Predictions, Their Confirmation, and Reward in Maintaining the Self-Concept

The predictive processing framework posits that people continuously use predictive principles when interacting with, learning from, and interpreting their surroundings. Here, we suggest that the same framework may help explain how people process self-relevant knowledge and maintain a stable and positive self-concept. Specifically, we recast two prominent self-relevant motivations, self-verification and self-enhancement, in predictive processing (PP) terms. We suggest that these self-relevant motivations interact with the self-concept (i.e., priors) to create strong predictions. These predictions, in turn, influence how people interpret information about themselves. In particular, we argue that these strong self-relevant predictions dictate how prediction error, the deviation from the original prediction, is processed. In contrast to many implementations of the PP framework, we suggest that predictions and priors emanating from stable constructs (such as the self-concept) cultivate belief-maintaining, rather than belief-updating, dynamics. Based on recent findings, we also postulate that evidence supporting a predicted model of the self (or interpreted as such) triggers subjective reward responses, potentially reinforcing existing beliefs. Characterizing the role of rewards in self-belief maintenance and reframing self-relevant motivations and rewards in predictive processing terms offers novel insights into how the self is maintained in neurotypical adults, as well as in pathological populations, potentially pointing to therapeutic implications.

Can the early visual processing of others' actions be related to social power and dominance?

Although goals often drive action understanding, this ability is also prone to important variability among individuals, which may have its origin in individual social characteristics. The present study aimed at evaluating the relationship between the tendency to prioritize goal information over grip information during early visual processing of action and several social dimensions. Visual processing of grip and goal information during action recognition was evaluated in 64 participants using the priming protocol developed by Decroix and Kalénine (Exp Brain Res 236(8):2411-2426, 2018). Object-directed action photographs were primed by photographs sharing the same goal and/or the same grip. The effects of goal and grip priming on action recognition were evaluated for different prime durations. The same participants further fulfilled questionnaires characterizing the way individuals deal with their social environment, namely their sense of social power, dominance, perspective taking, and construal level. At the group level, results confirmed greater goal than grip priming effects on action recognition for the shortest prime duration. Regression analyses between the pattern of response times in the action priming protocol and scores at the questionnaires further showed that the advantage of goal over grip priming was associated with higher sense of social power, and possibly to lower dominance. Overall, data confirm that observers tend to prioritize goal-related information when processing visual actions but further indicate that this tendency is sensitive to individual social characteristics. Results suggest that goal information may not always drive action understanding and point out the connection between low-level processing of observed actions and more general individual characteristics.

Angry facial expressions bias towards aversive actions

Social interaction requires fast and efficient processing of another person's intentions. In face-to-face interactions, aversive or appetitive actions typically co-occur with emotional expressions, allowing an observer to anticipate action intentions. In the present study, we investigated the influence of facial emotions on the processing of action intentions. Thirty-two participants were presented with video clips showing virtual agents displaying a facial emotion (angry vs. happy) while performing an action (punch vs. fist-bump) directed towards the observer. During each trial, video clips stopped at varying durations of the unfolding action, and participants had to recognize the presented action. Naturally, participants' recognition accuracy improved with increasing duration of the unfolding actions. Interestingly, while facial emotions did not influence accuracy, there was a significant influence on participants' action judgements. Participants were more likely to judge a presented action as a punch when agents showed an angry compared to a happy facial emotion. This effect was more pronounced in short video clips, showing only the beginning of an unfolding action, than in long video clips, showing near-complete actions. These results suggest that facial emotions influence anticipatory processing of action intentions allowing for fast and adaptive responses in social interactions.

New Horizons on Non-invasive Brain Stimulation of the Social and Affective Cerebellum

The cerebellum is increasingly attracting scientists interested in basic and clinical research of neuromodulation. Here, we review available studies that used either transcranial magnetic stimulation (TMS) or transcranial direct current stimulation (tDCS) to examine the role of the posterior cerebellum in different aspects of social and affective cognition, from mood regulation to emotion discrimination, and from the ability to identify biological motion to higher-level social inferences (mentalizing). We discuss how at the functional level the role of the posterior cerebellum in these different processes may be explained by a generic prediction mechanism and how the posterior cerebellum may exert this function within different cortico-cerebellar and cerebellar limbic networks involved in social cognition. Furthermore, we suggest to deepen our understanding of the cerebro-cerebellar circuits involved in different aspects of social cognition by employing promising stimulation approaches that have so far been primarily used to study cortical functions and networks, such as paired-pulse TMS, frequency-tuned stimulation, state-dependent protocols, and chronometric TMS. The ability to modulate cerebro-cerebellar connectivity opens up possible clinical applications for improving impairments in social and affective skills associated with cerebellar abnormalities.

Top-Down Attention Guidance Shapes Action Encoding in the pSTS

The posterior superior temporal sulcus (pSTS) is a brain region characterized by perceptual representations of human body actions that promote the understanding of observed behavior. Increasingly, action observation is recognized as being strongly shaped by the expectations of the observer (Kilner 2011; Koster-Hale and Saxe 2013; Patel et al. 2019). Therefore, to characterize top-down influences on action observation, we evaluated the statistical structure of multivariate activation patterns from the action observation network (AON) while observers attended to the different dimensions of action vignettes (the action kinematics, goal, or identity of avatars jumping or crouching). Decoding accuracy varied as a function of attention instruction in the right pSTS and left inferior frontal cortex (IFC), with the right pSTS classifying actions most accurately when observers attended to the action kinematics and the left IFC classifying most accurately when observed attended to the actor's goal. Functional connectivity also increased between the right pSTS and right IFC when observers attended to the actions portrayed in the vignettes. Our findings are evidence that the attentive state of the viewer modulates sensory representations in the pSTS, consistent with proposals that the pSTS occupies an interstitial zone mediating top-down context and bottom-up perceptual cues during action observation.

Predictive action perception from explicit intention information in autism

Social difficulties in autism spectrum disorder (ASD) may originate from a reduced top-down modulation of sensory information that prevents the spontaneous attribution of intentions to observed behaviour. However, although people with autism are able to explicitly reason about others' mental states, the effect of abstract intention information on perceptual processes has remained untested. ASD participants (n = 23) and a neurotypical (NT) control group (n = 23) observed a hand either reaching for an object or withdrawing from it. Prior to action onset, the participant either instructed the actor to "Take it" or "Leave it", or heard the actor state "I'll take it" or "I'll leave it", which provided an explicit intention that was equally likely to be congruent or incongruent with the subsequent action. The hand disappeared before completion of the action, and participants reported the last seen position of the tip of the index finger by touching the screen. NT participants exhibited a predictive bias in response to action direction (reaches perceived nearer the object, withdrawals perceived farther away), and in response to prior knowledge of the actor's intentions (nearer the object after "Take it", farther away after "Leave it"). However, ASD participants exhibited a predictive perceptual bias only in response to the explicit intentions, but not in response to the motion of the action itself. Perception in ASD is not immune from top-down modulation. However, the information must be explicitly presented independently from the stimulus itself, and not inferred from cues inherent in the stimulus.

People accurately predict the transition probabilities between actions

Social life is a complex dance. To coordinate gracefully with one's partners, one must predict their actions. Here, we investigated how people predict others' actions. We hypothesized that people can accurately predict others' future actions based on knowledge of their current actions, coupled with knowledge of action transitions. To test whether people have accurate knowledge of the transition probabilities between actions, we compared actual rates of action transitions-calculated from four large naturalistic datasets-to participants' ratings of the transition probabilities between corresponding sets of actions. In five preregistered studies, participants demonstrated accurate mental models of action transitions. Furthermore, we found that people drew upon conceptual knowledge of actions-described by the six-dimensional ACT-FASTaxonomy-to guide their accurate predictions. Together, these results indicate that people can accurately anticipate other people's moves in the dance of social life and that the structure of action knowledge may be tailored to making these predictions.

Challenges and opportunities for top-down modulation research in cognitive psychology

Studying social modulation of cognitive processes holds much promise for illuminating how, where, when and why social factors influence how we perceive and act in the world, as well as providing insight into the underlying cognitive mechanisms. This is no small objective; it reflects an ambitious programme of research. At present, based on the modal theoretical and methodological approach, we suggest that several challenges exist to achieving such lofty aims. These challenges span an overreliance on a simplistic dichotomy between "top-down" and "bottom-up" modulation, a lack of specificity about mechanisms that renders clear interpretations difficult, and theories that largely test against null hypotheses. We suggest that these challenges present several opportunities for new research and we encourage the field to abandon simplistic dichotomies and connect much more with existing research programmes such as semantics, memory and attention, which have all built diverse research platforms over many decades and that can help shape how social modulation is conceptualised and studied from a cognitive and brain perspective. We also outline ways that stronger theoretical positions can be taken, which avoid comparing to null hypotheses, and endorse methodological reform through fully embracing proposals from the open science movement and "credibility revolution". We feel that by taking these opportunities, the field will have a better chance of reaching its potential to build a cumulative science of social modulation that can inform understanding of basic cognitive and brain systems, as well as real-life social interactions and the varied abilities observed across the Autism Spectrum.

The neural basis of shared preference learning

During our daily lives, we often learn about the similarity of the traits and preferences of others to our own and use that information during our social interactions. However, it is unclear how the brain represents similarity between the self and others. One possible mechanism is to track similarity to oneself regardless of the identity of the other (Similarity account); an alternative is to track each other person in terms of consistency of their choice similarity with respect to the choices they have made before (consistency account). Our study combined functional Magnetic Resonance Imaging (fMRI) and computational modelling of reinforcement learning (RL) to investigate the neural processes that underlie learning about preference similarity. Participants chose which of two pieces of artwork they preferred and saw the choices of one agent who usually shared their preference and another agent who usually did not. We modelled neural activation with RL models based on the similarity and consistency accounts. Our results showed that activity in brain areas linked to reward and social cognition followed the consistency account. Our findings suggest that impressions of other people can be calculated in a person-specific manner, which assumes that each individual behaves consistently with their past choices.

What first drives visual attention during the recognition of object-directed actions? The role of kinematics and goal information

The recognition of others' object-directed actions is known to involve the decoding of both the visual kinematics of the action and the action goal. Yet whether action recognition is first guided by the processing of visual kinematics or by a prediction about the goal of the actor remains debated. In order to provide experimental evidence to this issue, the present study aimed at investigating whether visual attention would be preferentially captured by visual kinematics or by action goal information when processing others' actions. In a visual search task, participants were asked to find correct actions (e.g., drinking from glass) among distractor actions. Distractors actions contained grip and/or goal violations and could therefore share the correct goal and/or the correct grip with the target. The time course of fixation proportion on each distractor action has been taken as an indicator of visual attention allocation. Results show that visual attention is first captured by the distractor action with similar goal. Then the withdrawal of visual attention from the action distractor with similar goal suggests a later attentional capture by the action distractor with similar grip. Overall, results are in line with predictive approaches of action understanding, which assume that observers first make a prediction about the actor's goal before verifying this prediction using the visual kinematics of the action.

The sense of should: A biologically-based framework for modeling social pressure

What is social pressure, and how could it be adaptive to conform to others' expectations? Existing accounts highlight the importance of reputation and social sanctions. Yet, conformist behavior is multiply determined: sometimes, a person desires social regard, but at other times she feels obligated to behave a certain way, regardless of any reputational benefit-i.e. she feels a sense of should. We develop a formal model of this sense of should, beginning from a minimal set of biological premises: that the brain is predictive, that prediction error has a metabolic cost, and that metabolic costs are prospectively avoided. It follows that unpredictable environments impose metabolic costs, and in social environments these costs can be reduced by conforming to others' expectations. We elaborate on a sense of should's benefits and subjective experience, its likely developmental trajectory, and its relation to embodied mental inference. From this individualistic metabolic strategy, the emergent dynamics unify social phenomenon ranging from status quo biases, to communication and motivated cognition. We offer new solutions to long-studied problems (e.g. altruistic behavior), and show how compliance with arbitrary social practices is compelled without explicit sanctions. Social pressure may provide a foundation in individuals on which societies can be built.

Musical interaction is influenced by underlying predictive models and musical expertise

Musical interaction is a unique model for understanding humans’ ability to align goals, intentions, and actions, which also allows for the manipulation of participants’ internal predictive models of upcoming events. Here we used polyrhythms to construct two joint finger tapping tasks that even when rhythmically dissimilar resulted in equal inter-tap intervals (ITIs). Thus, behaviourally a dyad of two musicians tap isochronously at the same rate, yet with their own distinct rhythmical context model (RCM). We recruited 22 highly skilled musicians (in 11 dyads) and contrasted the effect of having a shared versus non-shared RCM on dyads’ synchronization behaviour. As expected, tapping synchronization was significantly worse at the start of trials with non-shared models compared to trials with a shared model. However, the musicians were able to quickly recover when holding dissimilar predictive models. We characterised the directionality in the tapping behaviour of the dyads and found patterns mostly of mutual adaptation. Yet, in a subset of dyads primarily consisting of drummers, we found significantly different synchronization patterns, suggesting that instrument expertise can significantly affect synchronization strategies. Overall, this demonstrates that holding different predictive models impacts synchronization in musicians performing joint finger tapping.

Cues to intention bias action perception toward the most efficient trajectory

Humans interpret others' behaviour as intentional and expect them to take the most energy-efficient path to achieve their goals. Recent studies show that these expectations of efficient action take the form of a prediction of an ideal "reference" trajectory, against which observed actions are evaluated, distorting their perceptual representation towards this expected path. Here we tested whether these predictions depend upon the implied intentionality of the stimulus. Participants saw videos of an actor reaching either efficiently (straight towards an object or arched over an obstacle) or inefficiently (straight towards obstacle or arched over empty space). The hand disappeared mid-trajectory and participants reported the last seen position on a touch-screen. As in prior research, judgments of inefficient actions were biased toward efficiency expectations (straight trajectories upwards to avoid obstacles, arched trajectories downward towards goals). In two further experimental groups, intentionality cues were removed by replacing the hand with a non-agentive ball (group 2), and by removing the action's biological motion profile (group 3). Removing these cues substantially reduced perceptual biases. Our results therefore confirm that the perception of others' actions is guided by expectations of efficient actions, which are triggered by the perception of semantic and motion cues to intentionality.

Spontaneous Vicarious Perception of the Content of Another's Visual Perspective

Visual perspective taking (VPT) is a core process of social cognition, providing humans with insights into what the environment looks like from another's point of view [1-4]. While VPT is often described as a quasi-perceptual phenomenon [5, 6], evidence for this proposal has been lacking. Here, we provide direct evidence that another's perspective can "stand in" for one's own sensory input during perceptual decision making. In a variant of the classic mental rotation task, participants judged whether characters presented in different orientations were canonical or mirror inverted. In the absence of another person, we replicate the well-established positive linear relationship between recognition times and angle of orientation such that recognition becomes slower the more an item has to be mentally rotated into its canonical orientation [7]. Importantly, this relationship was disrupted simply by placing another individual in the scene. Items rotated away from the participant were recognized more rapidly the closer they appeared in their canonical orientation, not only to the participant, but also to this other individual, showing that another's visual perspective drives mental rotation and item recognition in a similar way as one's own visual perspective. The effects were large and replicated in the three independent studies. They were observed even when the other person was completely passive, enhanced when the participant was explicitly instructed to take the other person's perspective, but reduced when the persons in the scenes were replaced with objects. The content of another's perspective is therefore spontaneously derived, takes a quasi-perceptual form, and can stand in for one's own sensory input during perceptual decision making.

Filling the gap despite full attention: the role of fast backward inferences for event completion

The comprehension of dynamic naturalistic events poses at least two challenges to the cognitive system: filtering relevant information with attention and dealing with information that was missing or missed. With four experiments, we studied the completion of missing information despite full attention. Participants watched short soccer video clips and we informed participants that we removed a critical moment of ball contact in half of the clips. We asked participants to detect whether these moments of ball contact were present or absent. In Experiment 1, participants gave their detection responses either directly during an event or delayed after an event. Although participants directed their full attention toward the critical contact moment, they were more likely to indicate seeing the missing ball contact if it was followed by a causally matching scene than if it was followed by an unrelated scene, both for the immediate and delayed responses. Thus, event completion occurs quickly. In Experiment 2, only a causally matching scene but neither a white mask nor an irrelevant scene caused the completion of missing information. This indicates that the completion of missing information is caused by backward inferences rather than predictive perception. In Experiment 3, we showed that event completion occurs directly during a trial and does not depend on expectations built up after seeing the same causality condition multiple times. In Experiment 4, we linked our findings to event cognition by asking participants to perform a natural segmentation task. We conclude that observers complete missing information during coherent events based on a fast backward inference mechanism even when directing their attention toward the missing information.

Perceptual teleology: expectations of action efficiency bias social perception

Primates interpret conspecific behaviour as goal-directed and expect others to achieve goals by the most efficient means possible. While this teleological stance is prominent in evolutionary and developmental theories of social cognition, little is known about the underlying mechanisms. In predictive models of social cognition, a perceptual prediction of an ideal efficient trajectory would be generated from prior knowledge against which the observed action is evaluated, distorting the perception of unexpected inefficient actions. To test this, participants observed an actor reach for an object with a straight or arched trajectory on a touch screen. The actions were made efficient or inefficient by adding or removing an obstructing object. The action disappeared mid-trajectory and participants touched the last seen screen position of the hand. Judgements of inefficient actions were biased towards the efficient prediction (straight trajectories upward to avoid the obstruction, arched trajectories downward towards the target). These corrections increased when the obstruction's presence/absence was explicitly acknowledged, and when the efficient trajectory was explicitly predicted. Additional supplementary experiments demonstrated that these biases occur during ongoing visual perception and/or immediately after motion offset. The teleological stance is at least partly perceptual, providing an ideal reference trajectory against which actual behaviour is evaluated.