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Expectations facilitate perception of expected stimuli but may hinder perception of unexpected alternatives. Here, we consider how prior expectations about others’ intentions are integrated with visual kinematics over time in detecting the intention of an observed motor act (grasp-to-pour vs. grasp-to-drink). Using rigorous psychophysics methods, we find that the processes of ascribing intentions to others are well described by drift diffusion models in which evidence from observed movements is accumulated over time until a decision threshold is reached. Testing of competing models revealed that when kinematics contained no discriminative intention information, prior expectations predicted the intention choice of the observer. When kinematics contained intention information, kinematics predicted the intention choice. These findings provide evidence for a diffusion process in which the influence of expectations is modulated by movement informativeness and informative kinematics can override initial expectations.

Highlights • Observation of others’ actions provides a shared experience of objects acted upon. • Observation of grasping movements provides a shared experience of object weight. • Object weight can be predictively judged from the kinematics of real grasps. • Weight judgements are also possible from the observation of pantomimed grasps., Observation of others’ actions has been proposed to provide a shared experience of the properties of objects acted upon. We report results that suggest a similar form of shared experience may be gleaned from the observation of pantomimed grasps, i.e., grasps aimed at pretended objects. In a weight judgment task, participants were asked to observe a hand reaching towards and grasping either a real or imagined glass, and to predictively judge its weight. Results indicate that participants were able to discriminate whether the to-be-grasped glass was empty, and thus light, or full, and thus heavy. Worthy of further investigation, this finding suggests that by observing others’ movements we can make predictions, and form expectations about the characteristics of objects that exist only in others’ minds.

This paper aims at investigating the action prediction problem from a pure kinematic perspective. Specifically, we address the problem of recognizing future actions, indeed human intentions, underlying a same initial (and apparently unrelated) motor act. This study is inspired by neuroscientific findings asserting that motor acts at the very onset are embedding information about the intention with which are performed, even when different intentions originate from a same class of movements. To demonstrate this claim in computational and empirical terms, we designed an ad hoc experiment and built a new 3D and 2D dataset where, in both training and testing, we analyze a same class of grasping movements underlying different intentions. We investigate how much the intention discriminants generalize across subjects, discovering that each subject tends to affect the prediction by his/her own bias. Inspired by the domain adaptation problem, we propose to interpret each subject as a domain, leading to a novel subject adversarial paradigm. The proposed approach favorably copes with our new problem, boosting the considered baseline features encoding 2D and 3D information and which do not exploit the subject information.

On many occasions, people spontaneously or deliberately take the perspective of a person facing them rather than their own perspective. How is this done? Using a spatial perspective task in which participants were asked to identify objects at specific locations, we found that self-perspective judgments were faster for objects presented to the right, rather than the left, and for objects presented closer to the participants’ own bodies. Strikingly, taking the opposing perspective of another person led to a reversal (i.e., remapping) of these effects, with reference to the other person’s position (Experiment 1). A remapping of spatial relations was also observed when an empty chair replaced the other person (Experiment 2), but not when access to the other viewpoint was blocked (Experiment 3). Thus, when the spatial scene allows a physically feasible but opposing point of view, people respond as if their own bodies were in that place. Imagination can thus overcome perception.

We asked whether previous observations of group interactions modulate subsequent social attention episodes. Participants first completed a learning phase with two conditions. In the ‘leader’ condition one of three identities turned her gaze first, followed by the two other faces. In the ‘follower’ condition, one of the identities turned her gaze after the two other faces had first shifted their gaze. Thus, participants observed that some individuals were consistently ‘leaders’ and others ‘followers’ of others’ attention. In the test phase, the faces of ‘leaders’ and ‘followers’ were presented in a gaze cueing paradigm. Remarkably, the ‘followers’ did not elicit gaze cueing. Our data demonstrate that individuals who do not guide group attention in exploring the environment are ineffective social attention directors in later encounters. Thus, the role played in previous group social attention interactions modulates the relative weight assigned to others’ gaze: we ignore the gaze of group followers.

Summary Can social gaze behavior reveal the leader during real-world group interactions? To answer this question, we developed a novel tripartite approach combining (1) computer vision methods for remote gaze estimation, (2) a detailed taxonomy to encode the implicit semantics of multi-party gaze features, and (3) machine learning methods to establish dependencies between leadership and visual behaviors. We found that social gaze behavior distinctively identified group leaders. Crucially, the relationship between leadership and gaze behavior generalized across democratic and autocratic leadership styles under conditions of low and high time-pressure, suggesting that gaze can serve as a general marker of leadership. These findings provide the first direct evidence that group visual patterns can reveal leadership across different social behaviors and validate a new promising method for monitoring natural group interactions., Graphical Abstract, Highlights • Leadership shapes gaze dynamics during real-world human group interactions • Social gaze behavior distinctively identifies group leaders • Identification generalizes across leadership styles and situational conditions • Gaze can serve as a general marker of leadership, Social Interaction; Neuroscience; Behavioral Neuroscience

Autism is a behavioral neurological disorder affecting a significant percentage of worldwide population. It especially starts manifesting at very low ages, but it is difficult to early diagnose it since there is not a specific exam or trial that is able to spot it safely. Its detection is in fact mainly dependent from the medical expertise used to assess the patient behavior during direct interviews. This work aims at providing an automatic objective support to the doctor for the assessment of (early) diagnosis of possible autistic subjects by only using video sequences. The underlying idea and rationale come from the psychological and neuroscience studies claiming that the executions of simple motor acts are different between pathological and healthy subjects, and this can be sufficient to discriminate between them. To this end, we devised an experiment in which we recorded, using a standard video camera, patient and healthy children performing the same simple gesture of grasping a bottle. By only processing the video clips depicting the grasping action using a recurrent deep neural network, we are able to discriminate with a good accuracy between the 2 classes of subjects. The designed deep model is also able to provide a sort of attention map in which the zones in the video of major interest are identified in space and time: this “explains” in a certain way which areas the model deems more relevant to the classification purpose, which could also be used by the doctor to make the diagnosis. In the end, this work constitutes a first step towards the development of an automatic computational system devoted to the early diagnosis of autistic subjects, providing the medical expert of a supportive objective method, potentially simple to use in clinical and also more open settings.

Recent years have seen accumulating evidence for the proposition that people process time by mapping it onto a linear spatial representation and automatically “project” themselves on an imaginedmental time line. Here, we ask whether people can adopt the temporal perspective of another person when travelling through time. To elucidate similarities and differences between time travelling from one’s own perspective or from the perspective of another person, we asked participants to mentally project themselves or someone else (i.e., a coexperimenter) to different time points. Three basic properties of mental time travel were manipulated: temporal location (i.e., where in time the travel originates: past, present, and future), motion direction (either backwards or forwards), and temporal duration (i.e., the distance to travel: one, three, or five years). We found that time travels originating in the present lasted longer in the self- than in the other-perspective. Moreover, for self-perspective, but not for other-perspective, time was differently scaled depending on where in time the travel originated. In contrast, when considering the direction and the duration of time travelling, no dissimilarities between the self- and the other-perspective emerged. These results suggest that self- and other-projection, despite some differences, share important similarities in structure.

The coordination of a leader with group members is very important for an effective leadership given that this figure is the person who actually manages the team members to achieve a desired goal. Investigating the leadership and especially the leadership style is a prominent research topic in social and organizational psychology. However this is a new problem in social signal processing that can actually make valuable contributions by analyzing multimodal data in a more effective and efficient way. In this work we identify the leadership style of an emergent leader (i.e. the leader who naturally arises from a group not designated) as autocratic or democratic. The proposed method is applied to a dataset in-the-wild; in other words there is no role-playing which is novel for this problem. Multiple kernel learning (MKL) using multimodal nonverbal features is utilized to predict leadership styles that proved to achieve better predictions as compared to traditional learning methods. Thanks to MKL and a simple heuristic proposed the best performing features are also identified showing that better predictions can be reached only by using those features. Additionally correlation analysis between the extracted nonverbal features and the results of social psychology questionnaire is also performed. This shows that significantly high correlations exist for speaking activity based and prosodic nonverbal features.

Several studies on visually guided reach-to-grasp movements have documented that how objects are grasped differs depending on the actions one intends to perform subsequently. However, no previous study has examined whether this differential grasping may also occur without visual input. In this study, we used motion capture technology to investigate the influence of visual feedback and prior visual experience on the modulation of kinematics by intention in sighted (in both full-vision and no-vision conditions), early-blind and late-blind participants. Results provide evidence of modulation of kinematics by intention to a similar degree under both full-vision and no-vision conditions. Moreover, they demonstrate that prior visual experience has little impact on the tailoring of grasping movements to intention. This suggests that sequential action planning does not depend on visual input, and may instead be ascribed to the function of multisensory-motor cortical network that operates and develops not only in light, but also in darkness.

Is it possible to understand the intentions of others by merely observing their movements? Current debate has been mainly focused on the role that mirror neurons and motor simulation may play in this process, with surprisingly little attention being devoted to how intentions are actually translated into movements. Here, we delineate an alternative approach to the problem of intention-from-movement understanding, which takes “action execution” rather than “action observation” as a starting point. We first consider whether and to what extent, during action execution, intentions shape movement kinematics. We then examine whether observers are sensitive to intention information conveyed by visual kinematics and can use this information to discriminate between different intentions. Finally, we consider the neural mechanisms that may contribute to intention-from-movement understanding. We argue that by reframing the relationship between intention and movement, this evidence opens new perspectives into the neurobiology of how we know other minds and predict others’ behavior.

Being able to comprehend communicative intentions and to recognize whether such intentions are directed toward us or not is extremely important in social interaction. Two brain systems, the mentalizing and the mirror neuron system, have been proposed to underlie intention recognition. However, little is still known about how the systems cooperate within the process of communicative intention understanding and to what degree they respond to self-directed and other-directed stimuli. To investigate the role of the mentalizing and the mirror neuron system, we used functional magnetic resonance imaging with four types of action sequence: communicative and private intentions as well as other-directed and self-directed intentions. Categorical and functional connectivity analyses showed that both systems contribute to the encoding of communicative intentions and that both systems are significantly stronger activated and more strongly coupled in self-directed communicative actions.

Drawing on sociocultural theories and Bayesian accounts of brain function, in this article we construe psychiatric conditions as disorders of social interaction to fully account for their complexity and dynamicity across levels of description and temporal scales. After an introduction of the theoretical underpinnings of our integrative approach, we take autism spectrum conditions (ASC) as a paradigm example and discuss how neurocognitive hypotheses can be translated into a Bayesian formulation, i.e., in terms of predictive processing and active inference. We then argue that consideration of individuals (even within a Bayesian framework) will not be enough for a comprehensive understanding of psychiatric conditions and consequently put forward the dialectical misattunement hypothesis, which views psychopathology not merely as disordered function within single brains but also as a dynamic interpersonal mismatch that encompasses various levels of description. Moving from a mere comparison of groups, i.e., “healthy” persons versus “patients,” to a fine-grained analysis of social interactions within dyads and groups of individuals will open new avenues and may allow to avoid an overly neurocentric scope in psychiatric research as well as help to reduce social exclusion.

How do we understand the intentions of other people? There has been a longstanding controversy over whether it is possible to understand others’ intentions by simply observing their movements. Here, we show that indeed movement kinematics can form the basis for intention detection. By combining kinematics and psychophysical methods with classification and regression tree (CART) modeling, we found that observers utilized a subset of discriminant kinematic features over the total kinematic pattern in order to detect intention from observation of simple motor acts. Intention discriminability covaried with movement kinematics on a trial-by-trial basis, and was directly related to the expression of discriminative features in the observed movements. These findings demonstrate a definable and measurable relationship between the specific features of observed movements and the ability to discriminate intention, providing quantitative evidence of the significance of movement kinematics for anticipating others’ intentional actions.

Behavioural and neuropsychological studies suggest that real actions and pantomimed actions tap, at least in part, different neural systems. Inspired by studies showing weight-attunement in real grasps, here we asked whether (and to what extent) kinematics of pantomimed reach-to-grasp movement can reveal the weight of the pretended target. To address this question, we instructed participants (n =15) either to grasp or pretend to grasp towards two differently weighted objects, i.e., a light object and heavy object. Using linear discriminant analysis, we then proceeded to classify the weight of the target – either real or pretended – on the basis of the recorded movement patterns. Classification analysis revealed that pantomimed reach-to-grasp movements retained information about object weight, although to a lesser extent than real grasp movements. These results are discussed in relation to the mechanisms underlying the control of real and pantomimed grasping movements.

This study was conducted to examine interpersonal predictive coding in individuals with high-functioning autism (HFA). Healthy and HFA participants observed point-light displays of two agents (A and B) performing separate actions. In the ‘communicative’ condition, the action performed by agent B responded to a communicative gesture performed by agent A. In the ‘individual’ condition, agent A's communicative action was substituted by a non-communicative action. Using a simultaneous masking-detection task, we demonstrate that observing agent A's communicative gesture enhanced visual discrimination of agent B for healthy controls, but not for participants with HFA. These results were not explained by differences in attentional factors as measured via eye-tracking, or by differences in the recognition of the point-light actions employed. Our findings, therefore, suggest that individuals with HFA are impaired in the use of social information to predict others' actions and provide behavioural evidence that such deficits could be closely related to impairments of predictive coding., Philosophical Transactions of the Royal Society B: Biological Sciences, 371 (1693), ISSN:0962-8436, ISSN:1471-2970, ISSN:0080-4622

Humans are able to mentally adopt the spatial perspective of others and represent the visual world from their point of view. Here, we present neuropsychological evidence that information inaccessible from an egocentric perspective can be accessed from the perspective of another person. Patients affected by left neglect were asked to describe arrays of objects from their own egocentric perspective, from an opposite perspective (disembodied perspective taking), and from the point of view of another person actually seated in front of them (embodied perspective taking). Although disembodied perspective-taking ameliorated neglect severity, there was an even stronger positive effect of embodied perspective-taking: items presented on the left and neglected when reported from the egocentric perspective were instead recovered when patients assumed the perspective of the other. These findings suggest that perspective-taking entails an altercentric remapping of space, i.e. remapping of objects and locations coded with reference to the other person's body.

Event-related functional magnetic resonance imaging (fMRI) was used to explore how the human brain models gaze-object relations. During scanning participants observed a human model gazing towards or away a target object presented either in isolation or flanked by a distractor object. In two further conditions the model's gaze was shifted and subsequently maintained away from the stimulus/i. These four conditions were implemented within a factorial design in which the main factors were "type of observed behavior" (gaze vs. gaze-away) and "context" (target alone vs. target flanked by a distractor). Results revealed that premotor, parietal and temporal areas, known to sub-serve the understanding of other people actions, were significantly more activated by the observation of the model gazing towards rather than away from the stimulus/i. In addition, a significant interaction indicated that, when the target was presented in isolation, neural activity within the inferior frontal gyrus, another key area for action understanding, was influenced by gaze-object relations. Our findings suggest that this area is important for the establishment of intentional gaze-object relations and indicate that the presence of a distractor interferes with the representation of such relations.

A growing body of work suggests that in some circumstances, humans may be capable of ascribing mental states to others in a way that is fast, cognitively efficient, and implicit (implicit mentalizing hypothesis). However, the interpretation of this work has recently been challenged by suggesting that the observed effects may reflect "submentalizing" effects of attention and memory, with no ascription of mental states (submentalizing hypothesis). The present study employed a strong test between these hypotheses by examining whether apparently automatic processing of another's visual perspective is influenced by experience-dependent beliefs about whether that person can see. Altercentric interference was observed when participants judged their own perspective on stimuli involving an avatar wearing goggles that participants believed to be transparent but not when they believed the goggles to be opaque. These results are consistent with participants ascribing mental states to the avatar and not with the submentalizing hypothesis that altercentric interference arises merely because avatars cue shifts in spatial attention. (PsycINFO Database Record

Previous research has provided evidence for a neural system underlying the observation of another person's hand actions. Is the neural system involved in this capacity also important in inferring another person's motor intentions toward an object from their eye gaze? In real-life situations, humans use eye movements to catch and direct the attention of others, often without any accompanying hand movements or speech. In an event-related functional magnetic resonance imaging study, subjects observed videos showing a human model either grasping a target object (grasping condition) or simply gazing (gaze condition) at the same object. These two conditions were contrasted with each other and against a control condition in which the human model was standing behind the object without performing any gazing or grasping action. The results revealed activations within the dorsal premotor cortex, the inferior frontal gyrus, the inferior parietal lobule, and the superior temporal sulcus in both “grasping” and “gaze” conditions. These findings suggest that signaling the presence of an object through gaze elicits in an observer a similar neural response to that elicited by the observation of a reach-to-grasp action performed on the same object.

As shown by neuroscientific evidence, neglect may occur without elementary sensorimotor impairments. The deficit is to be found at a higher, more abstract level of representation, which prevents the patient not only from seeing, but from conceiving the contralesional space. By analysing a series of neuropsychological results, in this paper we suggest a crucial role of time for the construction of a world: on this basis, we try to explain how it is possible that half the ontology gets lost. The analysis of the ontological implication of neglect will allow us to shed light on manifestations of the pathology apparently disconnected.

Recent studies show that what connotes an object is first of all a certain spatio-temporal structure. In this paper we describe some of the temporal features characterizing the temporal structure of objects: pre-existence, persistence, conservation of identity in spite of perceptive discontinuity, surviving changes in colour, size, and shape. We argue that time is an indispensable attribute for every type of object and briefly discuss the implication of this view with respect to a specific neuropsychological syndrome: unilateral spatial neglect.

Human social interactions often require people to take a different perspective than their own. Although much research has been done on egocentric spatial representation in a solo context, little is known about how space is mapped in relation to other bodies. Here we used a spatial perspective-taking paradigm to investigate whether observing a person holding his arms crossed over the body midline has an impact on the encoding of left/right and front/back spatial relations from that person’s perspective. In three experiments, we compared performance in a task in which spatial judgments were made from the perspective of the participant or from that of a co-experimenter. Depending on the experimental condition, the participant’s and the co-experimenter’s arms were either crossed or not crossed over the midline. Our results showed that crossing the arms had a specific effect on spatial judgments based on a first-person perspective. More specifically, the responses corresponding to the dominant hand side were slower in the crossed than in the uncrossed arms condition. Crucially, a similar effect was also found when the participants adopted the perspective of a person holding his arms crossed, but not when the other person’s arms were held in an unusual but uncrossed posture. Taken together these findings indicate that egocentric space and altercentric space are similarly coded in neurocognitive maps structured with respect to specific body segments.

Research in the field of psychology and cognitive neuroscience has begun to explore the functional underpinnings of voluntary actions and how they differ from stimulus-driven actions. From these studies one can conclude that the two action modes differ with respect to their neural and behavioural correlates. So far, however, no study has investigated whether the voluntary and stimulus-driven actions also differ in terms of motor programming. We report two experiments in which participants had to perform either voluntary or stimulus-driven reach-to-grasp actions upon the same stimulus. Using kinematic methods, in Experiment 1 we obtained evidence that voluntary actions and stimulus-driven actions translate into differential movement patterns. Results for Experiments 2 suggest that selecting what to do, when to act, and whether to act are characterized by specific kinematic signatures and affect different aspects of the reach-to-grasp movement in a selective fashion. These findings add to current models of volition suggesting that voluntary action control results from an interplay of dissociable subfunctions related to specific decision components: what action execute, when to execute an action, and whether to execute any action.

Previous research has shown that performing joint actions can lead to the representation of both one's own and others' actions. In the present study we explored the influence of co-representation on response stopping. Are joint actions more difficult to stop than solo actions? Using a variation of the stop-signal task, we found that participants needed more time to stop a planned joint action compared with a planned solo action (Experiment 1). This effect was not observed when participants performed the task in the presence of a passive observer (Experiment 2). A third transcranial magnetic stimulation experiment (Experiment 3) demonstrated that joint stopping recruited a more selective suppression mechanism than solo stopping. Taken together, these results suggest that participants used a global inhibition mechanism when acting alone; however, they recruited a more selective and slower suppression mechanism when acting with someone else. Language: en

Social objects have been at the centre of philosophical discussion and debate over the last decade. So far, however, little empirical work has been conducted on social objects and we are still at the very early stages of understanding how the brain permits us to represent, recognize, and constitute a social reality. In this chapter, we consider five core questions for a neuroscience of social objects: Are social objects a category of objects in the brain? When we use money or see it being used, do we employ similar representations as those of concrete tools such as screwdrivers? How do status functions emerge? Do social objects depend on a uniquely human ability to share goals and intentions? Do social objects influence the sensory-motor system? We speculate on ways in which these questions might be addressed combining behavioural, developmental, neuropsychological, and neuroimaging approaches.

A key component of social understanding is the ability to read intentions from movements. But how do we discern intentions in others’ actions? What kind of intention information is actually available in the features of others’ movements? Based on the assumption that intentions are hidden away in the other person’s mind, standard theories of social cognition have mainly focused on the contribution of higher-level processes. Here, we delineate an alternative approach to the problem of intention-from-movement understanding. We argue that intentions become ‘visible’ in the surface flow of agents’ motions. Consequently, the ability to understand others’ intentions cannot be divorced from the capability to detect essential kinematics. This hypothesis has far reaching implications for how we know other minds and predict others’ behavior.

Objects in the environment have a perceived value that can be changed through social influence. A subtle way to influence object evaluation is through eye gaze: Objects looked at by others are perceived as more likable than objects that are not looked at. In 3 experiments, we directly tested the hypothesis that this liking effect depends on the processing of the intentional relation between other's eye gaze and the object being looked at. To this end, we used a novel paradigm in which participants observed a face looking left or right behind an opaque barrier. Under all tested conditions, we found a gaze cueing effect on attention: Looked-at objects were categorized faster than looked-away objects. In contrast, observed gaze only led to a boost in affective evaluation for the target object when observers had the impression that the face could see the object behind the barrier, but not when observers had the impression that the face could not see the object. These findings indicate that observers make a sophisticated use of social gaze cues in the affective evaluation of objects: Objects looked at by others are liked more than objects looked away but only when others can see the objects.

What makes people spontaneously adopt the perspective of others? Previous work suggested that perspective taking can serve understanding the actions of others. Two studies corroborate and extend that interpretation. The first study varied cues to intentionality of eye gaze and action, and found that the more the actor was perceived as potentially interacting with the objects, the stronger the tendency to take his perspective. The second study investigated how manipulations of gaze affect the tendency to adopt the perspective of another reaching for an object. Eliminating gaze cues by blurring the actor's face did not reduce perspective-taking, suggesting that in the absence of gaze information, observers rely entirely on the action. Intriguingly, perspective-taking was higher when gaze and action did not signal the same intention, suggesting that in presence of ambiguous behavioral intention, people are more likely take the other's perspective to try to understand the action.

Does the human mind allow for self-locating at more than one place at a time? Evidence from neurology, cognitive neuroscience, and experimental psychology suggests that mental bilocation is a complex, but genuine experience, occurring more frequently than commonly thought. In this article, we distinguish between different components of bilocated self-representation: self-localization in two different places at the same time, self-identification with another body, reduplication of first-person perspective. We argue that different forms of mental bilocation may result from the combination of these components. To illustrate this, we discuss evidence of mental bilocation in pathological conditions such as heautoscopy, during immersion in virtual environments, and in everyday life, during social interaction. Finally, we consider the conditions for mental bilocation and speculate on the possible role of mental bilocation in the context of social interaction, suggesting that self-localization at two places at the same time may prove advantageous for the construction of a shared space.

Individuals show significant variations in performing a motor act. Previous studies in the action observation literature have largely ignored this ubiquitous, if often unwanted, characteristic of motor performance, assuming movement patterns to be highly similar across repetitions and individuals. In the present study, we examined the possibility that individual variations in motor style directly influence the ability to understand and predict others' actions. To this end, we first recorded grasping movements performed with different intents and used a two-step cluster analysis to identify quantitatively 'clusters' of movements performed with similar movement styles (Experiment 1). Next, using videos of the same movements, we proceeded to examine the influence of these styles on the ability to judge intention from action observation (Experiments 2 and 3). We found that motor styles directly influenced observers' ability to 'read' others' intention, with some styles always being less 'readable' than others. These results provide experimental support for the significance of motor variability for action prediction, suggesting that the ability to predict what another person is likely to do next directly depends on her individual movement style.

Predictive processes are crucial not only for interpreting the actions of individual agents, but also to predict how, in the context of a social interaction between two agents, the actions of one agent relate to the actions of a second agent. In the present study we investigated whether, in the context of a communicative interaction between two agents, observers can use the actions of one agent to predict when the action of a second agent will take place. Participants observed point-light displays of two agents (A and B) performing separate actions. In the communicative condition, the action performed by agent B responded to a communicative gesture performed by agent A. In the individual condition, agent A's communicative action was substituted with a non-communicative action. For each condition, we manipulated the temporal coupling of the actions of the two agents, by varying the onset of agent A's action. Using a simultaneous masking detection task, we demonstrated that the timing manipulation had a critical effect on the communicative condition, with the visual discrimination of agent B increasing linearly while approaching the original interaction timing. No effect of the timing manipulation was found for the individual condition. Our finding complements and extends previous evidence for interpersonal predictive coding, suggesting that the communicative gestures of one agent can serve not only to predict what the second agent will do, but also when his/her action will take place.

Skepticism has been expressed concerning the possibility to understand others’ intentions by simply observing their movements: Since a number of different intentions may have produced a particular action, motor information – it has been argued - might be sufficient to understand what an agent is doing, but not her remote goal in performing that action. Here we challenge this conclusion by showing that in the absence of contextual information, intentions can be inferred from body movement. Based on recent empirical findings, we shall contend that: i) intentions translate into differential kinematic patterns; ii) observers are especially attuned to kinematic information and can use early differences in visual kinematics to anticipate the intention of an agent in performing a given action; iii) during interacting activities, predictions about the future course of others’ actions tune online action planning; iv) motor activation during action observation subtends a complementary understanding of what the other is doing. These findings demonstrate that intention understanding is deeply rooted in social interaction: by simply observing others’ movements, we might know what they have in mind to do and how we should act in response.

Because the way we grasp an object varies depending on the intention with which the object is grasped, monitoring the properties of prehensile movements may provide access to a person's intention. Here we investigate the role of visual kinematics in the implicit coding of intention, by using functional brain imaging while participants observed grasping movements performed with social versus individual intents. The results show that activation within the mirror system is stronger during the observation of socially intended movements relative to individual movements. Moreover, areas that form the mentalizing system are more active during social grasping movements. These findings demonstrate that, in the absence of context information, social information conveyed by action kinematics modulates intention processing, leading to a transition from mirroring to mentalizing.

Human observers are especially sensitive to the actions of conspecifics that match their own actions. This has been proposed to be critical for social interaction, providing the basis for empathy and joint action. However, the precise relation between observed and executed actions is still poorly understood. Do ongoing actions change the way observers perceive others' actions? To pursue this question, we exploited the bistability of depth-ambiguous point-light walkers, which can be perceived as facing towards the viewer or as facing away from the viewer. We demonstrate that point-light walkers are perceived more often as facing the viewer when the observer is walking on a treadmill compared to when the observer is performing an action that does not match the observed behavior (e.g., cycling). These findings suggest that motor processes influence the perceived orientation of observed actions: Acting observers tend to perceive similar actions by conspecifics as oriented towards themselves. We discuss these results in light of the possible mechanisms subtending action-induced modulation of perception.

Background Beyond providing cues about an agent's intention, communicative actions convey information about the presence of a second agent towards whom the action is directed (second-agent information). In two psychophysical studies we investigated whether the perceptual system makes use of this information to infer the presence of a second agent when dealing with impoverished and/or noisy sensory input. Methodology/Principal Findings Participants observed point-light displays of two agents (A and B) performing separate actions. In the Communicative condition, agent B's action was performed in response to a communicative gesture by agent A. In the Individual condition, agent A's communicative action was replaced with a non-communicative action. Participants performed a simultaneous masking yes-no task, in which they were asked to detect the presence of agent B. In Experiment 1, we investigated whether criterion c was lowered in the Communicative condition compared to the Individual condition, thus reflecting a variation in perceptual expectations. In Experiment 2, we manipulated the congruence between A's communicative gesture and B's response, to ascertain whether the lowering of c in the Communicative condition reflected a truly perceptual effect. Results demonstrate that information extracted from communicative gestures influences the concurrent processing of biological motion by prompting perception of a second agent (second-agent effect). Conclusions/Significance We propose that this finding is best explained within a Bayesian framework, which gives a powerful rationale for the pervasive role of prior expectations in visual perception.

Background In the context of interacting activities requiring close-body contact such as fighting or dancing, the actions of one agent can be used to predict the actions of the second agent [1]. In the present study, we investigated whether interpersonal predictive coding extends to interactive activities – such as communicative interactions - in which no physical contingency is implied between the movements of the interacting individuals. Methodology/Principal Findings Participants observed point-light displays of two agents (A and B) performing separate actions. In the communicative condition, the action performed by agent B responded to a communicative gesture performed by agent A. In the individual condition, agent A's communicative action was substituted with a non-communicative action. Using a simultaneous masking detection task, we demonstrate that observing the communicative gesture performed by agent A enhanced visual discrimination of agent B. Conclusions/Significance Our finding complements and extends previous evidence for interpersonal predictive coding, suggesting that the communicative gestures of one agent can serve as a predictor for the expected actions of the respondent, even if no physical contact between agents is implied.

Body movement provides a rich source of cues about other people’s goals and intentions. In the present research, we investigate how well people can distinguish between different social intentions on the basis of movement information. Participants observed a model reaching toward and grasping a wooden block with the intent to cooperate with a partner, compete against an opponent, or perform an individual action. In Experiment 1, a temporal occlusion procedure was used as to determine whether advance information gained during the viewing of the initial phase of an action allowed the observers to discriminate across movements performed with different intentions. In Experiment 2, we examined what kind of cues observers relied upon for the discrimination of intentions by masking selected spatial areas of the model (i.e., the arm or the face) maintaining the same temporal occlusion as for Experiment 1. Results revealed that observers could readily judge whether the object was grasped with the intent to cooperate, compete, or perform an individual action. Seeing the arm was better than seeing the face for discriminating individual movements performed at different speeds (natural-speed vs. fast-speed individual movements). By contrast, seeing the face was better than seeing the arm for discriminating social from individual movements performed at a comparable speed (cooperative vs. natural-speed individual movements, competitive vs. fast-speed individual movements). These results demonstrate that observers are attuned to advance movement information from different cues and that they can use such kind of information to anticipate the future course of an action.

Body movement provides a rich source of information about other people's goals and intentions. In the present study, we examined a particular aspect concerned with the interpretation of bodily movement--how well people can distinguish between different social intentions by observing a reach-to-grasp movement. To ascertain to what extent intention-from-motion judgements rely on visual kinematics, we compared prediction performance on a typical temporal-occlusion video task with prediction performance on a temporal-occlusion point-light task. In the video task, participants observed videos showing a model reaching towards and grasping a wooden block with different intents: to cooperate with a partner in building a tower, compete with an opponent to be the first to put the object in the middle of the working surface, or perform an individual action. In the point-light task, participants observed point-light displays of the same movements. Although predictions were more accurate for the video task, prediction performance was not disrupted for the point-light task, suggesting that essential kinematic information available in point-light displays was indeed sufficient for intention-from-motion judgement. Importantly, the same kinematic landmarks were used to discriminate between social intentions for the video and the point-light task. This suggests that observers not only have the ability to use kinematic information when no other information is available, but they use kinematic information to discriminate between intentions when watching the motion of others under full light conditions.

BackgroundCast shadows in visual scenes can have profound effects on visual perception. Much as they are informative, they also constitute noise as they are salient features of the visual scene potentially interfering with the processing of other features. Here we asked i) whether individuals with autism can exploit the information conveyed by cast shadows; ii) whether they are especially sensitive to noise aspects of shadows.Methodology/principal findingsTwenty high-functioning children with autism and twenty typically developing children were asked to recognize familiar objects while the presence, position, and shape of the cast shadow were systematically manipulated. Analysis of vocal reaction time revealed that whereas typically developing children used information from cast shadows to improve object recognition, in autistic children the presence of cast shadows--either congruent or incongruent--interfered with object recognition. Critically, vocal reaction times were faster when the object was presented without a cast shadow.Conclusions/significanceWe conclude that shadow-processing mechanisms are abnormal in autism. As a result, processing shadows becomes costly and cast shadows interfere rather than help object recognition.

Four experiments investigated the influence of a sudden social request on the kinematics of a preplanned action. In Experiment 1, participants were requested to grasp an object and then locate it within a container (unperturbed trials). On 20% of trials, a human agent seated nearby the participant unexpectedly stretched out her arm and unfolded her hand as if to ask for the object (perturbed trials). In the remaining 3 experiments, similar procedures were adopted except that (a) the human was replaced by a robotic agent, (b) the gesture performed by the human agent did not imply a social request, and (c) the gaze of the human agent was not available. Only when the perturbation was characterized by a social request involving a human agent were there kinematic changes to the action directed toward the target. Conversely, no effects on kinematics were evident when the perturbation was caused by the robotic agent or by a human agent performing a nonsocial gesture. These findings are discussed in the light of current theories proposed to explain the effects of social context on the control of action.

An aspect of gaze processing, which so far has been given little attention, is the influence that intentional gaze processing can have on object processing. Converging evidence from behavioural neuroscience and developmental psychology strongly suggests that objects falling under the gaze of others acquire properties that they would not display if not looked at. Specifically, observing another person gazing at an object enriches that object of motor, affective and status properties that go beyond its chemical or physical structure. A conceptual analysis of available evidence leads to the conclusion that gaze has the potency to transfer to the object the intentionality of the person looking at it.

It has been proposed that motor contagion supplies the first step in mentalizing. Here, by using kinematic methods, we show that in contrast to normally developing children, children with autism seem to be immune to motor contagious processes. In the main experiment, involving twelve high-functioning autistic children (six males and six females, 10-13 years old, mean 11.1 years) and 12 normally developing controls (age and gender matched), two participants, a model and an observer, were seated facing each other at a table. The model was a normally developing child but the observer was either a normally developing or autistic child. The model was requested to grasp a stimulus or simply to gaze towards the target which could be presented alone or flanked by a distractor object. After watching the model, the observer was asked to grasp the object (always in the absence of the distractor). Despite the distractor being removed, the kinematics of normally developing children was affected by having observed an action performed in the presence of a distractor, thus revealing a transfer of interference from the model's action. Consistent with prior evidence, this transfer of interference effect was also present when the model simply looked at the target in the presence of the distractor object. In contrast, autistic children did not show any interference effect either from action or from gaze observation. A control experiment explored the importance of the information coming from the model's gaze pattern in eliciting the effects of motor contagion in normally developing children. In this case, the model was asked to fix their eyes on the target despite the presence of the distractor. Results highlight the importance of gaze direction in motor contagion, demonstrating that in normal children blocking the gaze prevented the transfer of interference. Altogether, these findings suggest that eye gaze plays a central role in eliciting motor contagion. We discuss these results in light of the deficit exhibited by children with autism in reading intentions from gaze.

The aim of the present study is to elucidate the influence of context on the kinematics of the reach-to-grasp movement. In particular, we consider two basic modes of social cognition, namely cooperation and competition. In two experiments kinematics of the very same action - reaching-to-grasp a wooden block - were analyzed in two different contexts provided by a cooperative task and competitive task. For the 'cooperation' tasks two participants were required to reach and grasp their respective objects and to cooperate to join the two objects in specific configurations in the middle of the working surface. For the 'competition' tasks, the two participants had to compete to place their own object first in the middle of the working surface. Results revealed specific kinematic patterns for cooperation and competition which were distinct from similar actions performed by each participant in isolation. Further, during the cooperation tasks, a high level of correlation between key kinematical parameters of the two participants was found. In accordance with evidence from neuroimaging, developmental and social psychology our results suggest the existence of motor patterns which reflect the intention to act in a social context. Cognition

In this paper we present theoretical and experimental evidence for a set of mechanisms by which intention is understood. We propose that three basic aspects are involved in the understanding of intention. The first aspect to consider is intention recognition, i.e., the process by which we recognize other people's intentions, distinguishing among different types. The second aspect concerns the attribution of intention to its author: the existence of shared neural representations provides a parsimonious explanation of how we recognize other people's intentions (what they are doing), but in and of itself, is not sufficient to determine who the agent is. Once the intention has been recognized and attributed to an agent, the reasons for, and the aim of, the intention are to be considered. Hence, the third aspect concerns the aim-intention motivating the execution of a certain action. We discuss the neural basis of these three theoretical aspects suggesting a conceptual synthesis.

Temporality enters our immediate experience as passage and becoming: the role time plays in the construction of a world of enduring entities tends to go unnoticed. This paper examines the relation between time and ontology in the context of unilateral neglect, a neuropsychological syndrome in which patients fail to perceive or respond to stimuli in the contralateral hemifield, behaving as if that half of space does not exist. Traditional models characterize neglect exclusively in spatial terms. Based on recent investigations suggesting abnormal temporal dynamics, here we highlight the impact of time factors on the presentation of the disorder. Neglect patients do not simply miss the presence of stimuli on the left: they also ignore the past as well as the future of neglected stimuli. We claim that, if this occurs, it is because time, and not only space, is impaired.

In this paper we discuss the problem of the neural conditions of shared attitudes and intentions: which neural mechanisms underlie “we-mode” processes or serve as precursors to such processes? Neurophysiological and neuropsychological evidence suggests that in different areas of the brain neural representations are shared by several individuals. This situation, on the one hand, creates a potential problem for correct attribution. On the other hand, it may provide the conditions for shared attitudes and intentions.

Recent findings suggest that in dyadic contexts observers rapidly and involuntarily process the visual perspective of others and cannot easily resist interference from their viewpoint. To investigate whether spontaneous perspective taking extends beyond dyads, we employed a novel visual perspective task that required participants to select between multiple competing perspectives. Participants were asked to judge their own perspective or the visual perspective of one or two avatars who either looked at the same objects or looked at different objects. Results indicate that when a single avatar was present in the room, participants processed the irrelevant perspective even when it interfered with participants' explicit judgments about the relevant perspective. A similar interference effect was observed when two avatars looked at the same discs, but not when they looked at different discs. Indeed, when the two avatars looked at different discs, the interference from the irrelevant perspective was significantly reduced. This is the first evidence that the number and orientation of agents modulate spontaneous perspective taking in non-dyadic contexts: observers may efficiently compute another's perspective, but in presence of more individuals holding discrepant perspectives, they may not spontaneously track multiple viewpoints. These findings are discussed in relation to the hypothesis that perspective calculation occurs in an effortless and automatic manner.

Is our attitude to money like that to any other tool even though its use is symbolic and is not implemented in its physical structure? Knowledge of the functional use of concrete tools, such as hammers or screwdrivers, has been associated with activation of a left hemisphere network including the posterior temporal cortex, supramarginal gyrus, inferior parietal lobule, and lateral precuneus. Here we demonstrate that observing bank notes being cut up or torn, a critical violation of their function, elicits activation within the same temporo-parietal network. Moreover, this activation is the greater the higher the value of the banknote. This lends plausibility to a genuinely psychological interpretation of the explanation of money as a tool for parametrically symbolizing exchange.