Long- and short-term plastic modeling of action prediction abilities in volleyball

Athletes show superior abilities not only in executing complex actions, but also in anticipating others' moves. Here, we explored how visual and motor experiences contribute to forge elite action prediction abilities in volleyball players. Both adult athletes and supporters were more accurate than novices in predicting the fate of volleyball floating services by viewing the initial ball trajectory, while only athletes could base their predictions on body kinematics. Importantly, adolescents assigned to physical practice training improved their ability to predict the fate of the actions by reading body kinematics, while those assigned to the observational practice training improved only in understanding the ball trajectory. The results suggest that physical and observational practice might provide complementary and mutually reinforcing contributions to the superior perceptual abilities of elite athletes. Moreover, direct motor experience is required to establish novel perceptuo-motor representations that are used to predict others' actions ahead of realization.     

Does how I look at what you're doing depend on what I'm doing?

Previous studies showed that people proactively gaze at the target of another's action by taking advantage of their own motor representation of that action. But just how selectively is one's own motor representation implicated in another's action processing? If people observe another's action while performing a compatible or an incompatible action themselves, will this impact on their gaze behaviour? We recorded proactive eye movements while participants observed an actor grasping small or large objects. The participants' right hand either freely rested on the table or held with a suitable grip a large or a small object, respectively. Proactivity of gaze behaviour significantly decreased when participants observed the actor reaching her target with a grip that was incompatible with respect to that used by them to hold the object in their own hand. This indicates that effective observation of action may depend on what one is actually doing, being actions observed best when the suitable motor representations may be readily recruited.     

The handedness of imagined bodies in action and the role of perspective taking

Past research at the nexus of motor control and perception investigated the role of perspective taking in many behavioral and neuroimaging studies. Some investigators addressed the issue of one's own vs. others' action imagination, but the possible effects of a front or a back view in imagining others' actions have so far been neglected. We report two 'single trial' experiments in which a total of 640 participants were asked to imagine a person performing a manual action - either in a front or in a back view - and then to indicate the hand used by the imagined person during movement execution. In such a task, we assume the existence of two distinct biases: a perceptual-mnemonic bias due to subjects' visual experience of others' actions, encouraging them to imagine right-handed movements, and a motor bias due to subjects' experience of self-made actions, encouraging them to imagine movements performed with the same hand as their dominant hand. We hypothesized that a greater involvement of motor representations in the back view compared to the front view could result in an increased correspondence between one's own manual preference and the hand used by the imagined agent in the former condition. The results of both experiments were consistent with this hypothesis, suggesting that while imagining others' actions we employ motor simulations in different degrees according to the perspective adopted.     

Action production influences 12-month-old infants' attention to others' actions

Recent work implicates a link between action control systems and action understanding. In this study, we investigated the role of the motor system in the development of visual anticipation of others' actions. Twelve-month-olds engaged in behavioral and observation tasks. Containment activity, infants' spontaneous engagement in producing containment actions; and gaze latency, how quickly they shifted gaze to the goal object of another's containment actions, were measured. Findings revealed a positive relationship: infants who received the behavior task first evidenced a strong correlation between their own actions and their subsequent gaze latency of another's actions. Learning over the course of trials was not evident. These findings demonstrate a direct influence of the motor system on online visual attention to others' actions early in development.     

Authorship effects in the prediction of handwriting strokes: Evidence for action simulation during action perception

Does the action system contribute to action perception? Recent evidence suggests that actions are simulated while being observed. Given that the planning and simulating system are the same only when one observes one's own actions, it might be easier to predict the future outcomes of actions when one has carried them out oneself earlier on. In order to test this hypothesis, three experiments were conducted in which participants observed parts of earlier self- and other-produced trajectories and judged whether another stroke would follow or not. When the trajectories were produced without constraints, participants accomplished this task only for self-produced trajectories. When the trajectories were produced under narrow constraints, the predictions were equally accurate for self- and for other-generated trajectories. These results support the action simulation assumption. The more the actions that one observes resemble the way one would carry them out oneself, the more accurate the simulation.     

Predicting others' actions via grasp and gaze: evidence for distinct brain networks

During social interactions, how do we predict what other people are going to do next? One view is that we use our own motor experience to simulate and predict other people's actions. For example, when we see Sally look at a coffee cup or grasp a hammer, our own motor system provides a signal that anticipates her next action. Previous research has typically examined such gaze and grasp-based simulation processes separately, and it is not known whether similar cognitive and brain systems underpin the perception of object-directed gaze and grasp. Here we use functional magnetic resonance imaging to examine to what extent gaze- and grasp-perception rely on common or distinct brain networks. Using a 'peeping window' protocol, we controlled what an observed actor could see and grasp. The actor could peep through one window to see if an object was present and reach through a different window to grasp the object. However, the actor could not peep and grasp at the same time. We compared gaze and grasp conditions where an object was present with matched conditions where the object was absent. When participants observed another person gaze at an object, left anterior inferior parietal lobule (aIPL) and parietal operculum showed a greater response than when the object was absent. In contrast, when participants observed the actor grasp an object, premotor, posterior parietal, fusiform and middle occipital brain regions showed a greater response than when the object was absent. These results point towards a division in the neural substrates for different types of motor simulation. We suggest that left aIPL and parietal operculum are involved in a predictive process that signals a future hand interaction with an object based on another person's eye gaze, whereas a broader set of brain areas, including parts of the action observation network, are engaged during observation of an ongoing object-directed hand action.     

When the rules are reversed: Action-monitoring consequences of reversing stimulus–response mappings

How does switching tasks affect our ability to monitor and adapt our behavior? Largely independent lines of research have examined how individuals monitor their actions and adjust to errors, on the one hand, and how they are able to switch between two or more tasks, on the other. Few studies, however, have explored how these two aspects of cognitive?Cbehavioral flexibility interact. That is, how individuals monitor their actions when task rules are switched remains unknown. The present study sought to address this question by examining the action-monitoring consequences of response switching??a form of task switching that involves switching the response that is associated with a particular stimulus. We recorded event-related brain potentials (ERPs) while participants performed a modified letter flanker task in which the stimulus?Cresponse (S?CR) mappings were reversed between blocks. Specifically, we examined three ERPs??the N2, the error-related negativity (ERN), and the error positivity (Pe)??that have been closely associated with action monitoring. The findings revealed that S?CR reversal blocks were associated with dynamic alterations of action-monitoring brain activity: the N2 and ERN were enhanced, whereas the Pe was reduced. Moreover, participants were less likely to adapt their posterror behavior in S?CR reversal blocks. Taken together, these data suggest that response switching results in early enhancements of effortful control mechanisms (N2 and ERN) at the expense of reductions in later response evaluation processes (Pe). Thus, when rules change, our attempts at control are accompanied by less attention to our actions.     

Bridging the gap between the other and me: the functional role of motor resonance and action effects in infants' imitation

This paper investigates a two-stage model of infants' imitative learning from observed actions and their effects. According to this model, the observation of another person's action activates the corresponding motor code in the infants' motor repertoire (i.e. leads to motor resonance). The second process guiding imitative behavior results from the observed action effects. If the modeled action is followed by a salient action effect, the representation of this effect (i.e. perceptual code) will be associated with the activated motor code. If the infant later aims to obtain the same effect, the corresponding motor program will be activated and the model's action will therefore be imitated. Accordingly, the model assumes that for the imitation of novel actions the modeled action needs to elicit sufficient motor resonance and must be followed by a salient action effect. Using the head touch imitation paradigm, we tested these two assumptions derived from the model. To this end, we manipulated whether the actions demonstrated to the infants were or were not in the motor repertoire, i.e. elicited stronger or less strong motor resonance, and whether they were followed by salient action effects or not. The results were in line with the proposed two-stage model of infants' imitative learning and suggest that motor resonance is necessary, but not sufficient for infants' imitative learning from others' actions and their effects.     

The temporal dynamics of the perceptual consequences of action-effect prediction

An essential aspect of voluntary action control is the ability to predict the perceptual effects of our actions. Although the influence of action-effect prediction on humans’ behavior and perception is unequivocal, it remains unclear when action-effect prediction is generated by the brain. The present study investigates the dynamics of action effect anticipation by tracing the time course of its perceptual consequences. Participants completed an acquisition phase during which specific actions (left and right key-presses) were associated with specific visual effects (upward and downward dots motion). In the test phase they performed a 2 AFC identification task in which they were required to indicate whether the dots moved upward or downward. To isolate any effects of action-effect prediction on perception, participants were presented with congruent and incongruent dot motion in which the association participants learned in the previous acquisition phase was respected and violated, respectively. Crucially, to assess the temporal dynamics of action prediction, congruent and incongruent stimuli were presented at different intervals before or after action execution. We observed higher sensitivity (d′) to motion discrimination in congruent vs. incongruent trials only when stimuli were presented from about 220 ms before the action to 280 ms after the action. The temporal dynamics of our effect suggest that action-effect prediction modulates perception at later stages of motor preparation.     

The predictive mirror: interactions of mirror and affordance processes during action observation

An important question for the study of social interactions is how the motor actions of others are represented. Research has demonstrated that simply watching someone perform an action activates a similar motor representation in oneself. Key issues include (1) the automaticity of such processes, and (2) the role object affordances play in establishing motor representations of others' actions. Participants were asked to move a lever to the left or right to respond to the grip width of a hand moving across a workspace. Stimulus-response compatibility effects were modulated by two task-irrelevant aspects of the visual stimulus: the observed reach direction and the match between hand-grasp and the affordance evoked by an incidentally presented visual object. These findings demonstrate that the observation of another person's actions automatically evokes sophisticated motor representations that reflect the relationship between actions and objects even when an action is not directed towards an object.     

Motor priming by movement observation with contralateral concurrent action execution

In the present study, the influence of simultaneous action execution on motor priming was investigated during movement observation using a simple-reaction task. Although previous studies have reported various effects of priming on motor performance, it has not yet been clarified how an additional source conveying kinetic information would modulate the priming effects. In the experiment, participants were asked to respond to an auditory cue by flexing their wrist while observing a line movement, which was slowly swinging like an inverted pendulum. In addition to the observation of line movement, the participants executed wrist flexion-extension actions synchronizing with line movement. The hand involved in pre-response wrist action varied with the priming condition: no movement execution (observation only), contralateral hand, and ipsilateral hand. In the contralateral condition, the stimulus-response congruency of movement direction was conflicted depending on the frame of reference (visual vs. anatomical coordinates). We found that all three priming conditions produced the compatibility effect, and the effect size did not differ between them. Importantly, in the contralateral condition, participants responded faster when the direction of line movement was congruent with the response movement in the anatomical coordinates. That is, the reaction time was shorter when pre-response action execution was in the flexion phase, even though the direction of observed movement and the response action were incongruent from the participants’ view. These results suggest that kinetic information has a great contribution to the motor priming system, which can reverse the vision-based compatibility effect.     

Behavioral speed contagion: automatic modulation of movement timing by observation of body movements

To coordinate our actions with those of others, it is crucial to not only choose an appropriate category of action but also to execute it at an appropriate timing. It is widely documented that people tend to unconsciously mimic others' behavior. The present study show that people also tend to modify their movement timing according to others' movements even when the observed and the to-be-executed movements are unrelated. Observers viewed either point-light biological motion, scrambled biological motion, or solid object motion. The stimulus sequence was presented at three different (half, normal, and double) rates. After a 300-2400-ms blank period, the observers performed a simple choice reaction-time task that was unrelated to the presented stimulus sequence. The observation of the biological motion produced a negative correlation between reaction time and stimulus speed, whereas no such trend was observed with the scrambled or solid object motion. Furthermore, speed-dependent modulation occurred only when the task was imposed within approximately 1s after the offset of the biological motion. These results suggest that behavioral tempo may be contagious; the speed of others' movements may automatically influence the timing of movement execution by the observer.     

Self-recognition of highly skilled actions: A study of orchestral conductors

The influence of movement skill on action representations and identification of agency was investigated. Point-light displays were created of highly skilled gestures of thirteen orchestral conductors in visual, auditory, and audiovisual versions and compared to two control conditions (static images and gait cycles of the same participants). In subsequent experimental sessions, participants indicated whether displays presented them or other conductors, whether the soundtrack contained their or others' musical interpretations, and rated the quality and emotional content of the gestures. Self-recognition was more accurate in conditions presenting highly skilled conducting movements as compared to other displays. Participants judged the quality of their own movements to be better than those of others, independently of whether or not they recognized movement agency. Emotional content was perceived accurately across conditions both for own and others' actions. These results point to the influence of dynamical characteristics of motor skill, rather than merely type of movement or emotional content, on action representations and self-other identification.     

Relative contributions of goal representation and kinematic information to self-monitoring by chimpanzees and humans

It is important to monitor feedback related to the intended result of an action while executing that action. This monitoring process occurs hierarchically; that is, sensorimotor processing occurs at a lower level, and conceptual representation of action goals occurs at a higher level. Although the hierarchical nature of self-monitoring may derive from the evolutionary history of humans, little is known about this cognitive process in non-human primates. This study showed that the relative contributions of kinematic information and goal representations to self-monitoring differ for chimpanzees and humans. Both species performed aiming actions whereby participants moved a cursor to hit targets. Additionally, a distractor cursor was presented simultaneously, and participants discriminated the cursor under their control from the cursor not under their control. The results showed that chimpanzees found it difficult to determine whether they were controlling the distractor when it moved toward the target, even though the distractor's kinematics and the participant's actions were dissociated. In contrast, humans performed efficiently regardless of any overlap between the presumptive and observed goals of the action. Our results suggest that goal representation, rather than motor kinematics, is the primary source of information for self-monitoring in chimpanzees, whereas humans efficiently integrate both dimensions of information. Our results are consistent with evidence showing species differences during imitation of others' actions, and suggest that humans have evolved the cognitive capacity to monitor motor kinematics in a more flexible manner than have chimpanzees.     

Joint action: bodies and minds moving together

The ability to coordinate our actions with those of others is crucial for our success as individuals and as a species. Progress in understanding the cognitive and neural processes involved in joint action has been slow and sparse, because cognitive neuroscientists have predominantly studied individual minds and brains in isolation. However, in recent years, major advances have been made by investigating perception and action in social context. In this article we outline how studies on joint attention, action observation, task sharing, action coordination and agency contribute to the understanding of the cognitive and neural processes supporting joint action. Several mechanisms are proposed that allow individuals to share representations, to predict actions, and to integrate predicted effects of own and others' actions.     

Translating visual information into action predictions: Statistical learning in action and nonaction contexts

Humans are sensitive to the statistical regularities in action sequences carried out by others. In the present eyetracking study, we investigated whether this sensitivity can support the prediction of upcoming actions when observing unfamiliar action sequences. In two between-subjects conditions, we examined whether observers would be more sensitive to statistical regularities in sequences performed by a human agent versus self-propelled ‘ghost’ events. Secondly, we investigated whether regularities are learned better when they are associated with contingent effects. Both implicit and explicit measures of learning were compared between agent and ghost conditions. Implicit learning was measured via predictive eye movements to upcoming actions or events, and explicit learning was measured via both uninstructed reproduction of the action sequences and verbal reports of the regularities. The findings revealed that participants, regardless of condition, readily learned the regularities and made correct predictive eye movements to upcoming events during online observation. However, different patterns of explicit-learning outcomes emerged following observation: Participants were most likely to re-create the sequence regularities and to verbally report them when they had observed an actor create a contingent effect. These results suggest that the shift from implicit predictions to explicit knowledge of what has been learned is facilitated when observers perceive another agent’s actions and when these actions cause effects. These findings are discussed with respect to the potential role of the motor system in modulating how statistical regularities are learned and used to modify behavior.     

Relations between infants’ emerging reach‐grasp competence and event‐related desynchronization in EEG

Recent reports of similar patterns of brain electrical activity (electroencephalogram: EEG) during action execution and observation, recorded from scalp locations over motor‐related regions in infants and adults, have raised the possibility that two foundational abilities – controlling one's own intentional actions and perceiving others’ actions – may be integrally related during ontogeny. However, to our knowledge, there are no published reports of the relations between developments in motor skill (i.e. recording actual motor skill performance) and EEG during both action execution and action observation. In the present study we collected EEG from 21 9‐month‐olds who were given opportunities to reach for toys and who also observed an experimenter reach for toys. Event‐related desynchronization (ERD) was computed from the EEG during the reaching events. We assessed infants’ reaching‐grasping competence, including reach latency, errors, preshaping of the hand, and bimanual reaches, and found that desynchronization recorded in scalp electrodes over motor‐related regions during action observation was associated with action competence during execution. Infants who were more competent reachers, compared to less competent reachers, exhibited greater ERD while observing reaching‐grasping. These results provide initial evidence for an early emerging neural system integrating one's own actions with the perception of others’ actions.     

Bend it like Beckham: Embodying the motor skills of famous athletes

Observing an action activates the same representations as does the actual performance of the action. Here we show for the first time that the action system can also be activated in the complete absence of action perception. When the participants had to identify the faces of famous athletes, the responses were influenced by their similarity to the motor skills of the athletes. Thus, the motor skills of the viewed athletes were retrieved automatically during person identification and had a direct influence on the action system of the observer. However, our results also indicated that motor behaviours that are implicit characteristics of other people are represented differently from when actions are directly observed. That is, unlike the facilitatory effects reported when actions were seen, the embodiment of the motor behaviour that is not concurrently perceived gave rise to contrast effects where responses similar to the behaviour of the athletes were inhibited.     

Bend it like Beckham: embodying the motor skills of famous athletes

Observing an action activates the same representations as does the actual performance of the action. Here we show for the first time that the action system can also be activated in the complete absence of action perception. When the participants had to identify the faces of famous athletes, the responses were influenced by their similarity to the motor skills of the athletes. Thus, the motor skills of the viewed athletes were retrieved automatically during person identification and had a direct influence on the action system of the observer. However, our results also indicated that motor behaviours that are implicit characteristics of other people are represented differently from when actions are directly observed. That is, unlike the facilitatory effects reported when actions were seen, the embodiment of the motor behaviour that is not concurrently perceived gave rise to contrast effects where responses similar to the behaviour of the athletes were inhibited.     

Looking is not enough: Multimodal attention supports the real-time learning of new words

Most research on early language learning focuses on the objects that infants see and the words they hear in their daily lives, although growing evidence suggests that motor development is also closely tied to language development. To study the real-time behaviors required for learning new words during free-flowing toy play, we measured infants’ visual attention and manual actions on to-be-learned toys. Parents and 12-to-26-month-old infants wore wireless head-mounted eye trackers, allowing them to move freely around a home-like lab environment. After the play session, infants were tested on their knowledge of object-label mappings. We found that how often parents named objects during play did not predict learning, but instead, it was infants’ attention during and around a labeling utterance that predicted whether an object-label mapping was learned. More specifically, we found that infant visual attention alone did not predict word learning. Instead, coordinated, multimodal attention–when infants’ hands and eyes were attending to the same object–predicted word learning. Our results implicate a causal pathway through which infants’ bodily actions play a critical role in early word learning.