Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> The Sense of Agency during Passive Observation of Other Humans <s> Awareness of actions is partly based on the intentions accompanying them. Thus, the awareness of self- and other-generated actions should differ to the extent that access to own and other's intentions differs. Recent studies have found a brain circuit (the mirrorneuron system) that represents self- and other-generated actions in an integrated fashion. This system does not respond to actions made by nonagents, such as machines. We measured the estimated onset time of actions that subjects either executed themselves or observed being executed by someone else or by a machine. In three experiments, the estimates of the machine actions always differed from those of self- and other-generated actions, whereas the latter two were indistinguishable. Our results are consistent with the view that intentions are attributed to others but not to machines. They also raise the interesting possibility that people attribute intentions to themselves in the same way as they do to others. <s> BIB001 </s> Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> The Sense of Agency during Passive Observation of Other Humans <s> Participants watched themselves in a mirror while another person behind them, hidden from view, extended hands forward on each side where participants' hands would normally appear. The hands performed a series of movements. When participants could hear instructions previewing each movement, they reported an enhanced feeling of controlling the hands. Hearing instructions for the movements also enhanced skin conductance responses when a rubber band was snapped on the other's wrist after the movements. Such vicarious agency was not felt when the instructions followed the movements, and participants' own covert movement mimicry was not essential to the influence of previews on reported control. <s> BIB002 </s> Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> The Sense of Agency during Passive Observation of Other Humans <s> Abstract Recently, it has been shown that the perceived times of voluntary movements and their effects are perceived as shifted towards each other. This temporal binding phenomenon was explained by an integrated representation of movement and effect, facilitating operant learning and the experience of intentionality. Here, we investigated whether temporal binding depends on explicit intentional attributions. In Experiment 1, participants intended to either produce or avoid producing an effect (a tone) by the timing of their movements, with the ratio of success being fixed at 2:1. In Experiments 2 and 3, the influence of the action–effect contingency ratio on temporal binding was controlled for by removing the intentional attribution of the effect. The results indicate that temporal binding is a general associative mechanism that facilitates the learning of movement–effect contingencies. Beyond that, temporal binding is sensitive to explicit intentional attributions, which selectively enhance the link between an intentional movement and the effect a moving agent intends to produce. <s> BIB003 </s> Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> The Sense of Agency during Passive Observation of Other Humans <s> Abstract The sense of agency (“I did that”) is a basic feature of our subjective experience. Experimental studies usually focus on either its attributional aspects (the “I” of “I did that”) or on its motoric aspects (the “did” aspect of “I did that”). Here, we combine both aspects and focus on the subjective experience of the time between action and effect. Previous studies [Haggard, P., Aschersleben, G., Gehrke, J., & Prinz, W. (2002a). Action, binding and awareness. In W. Prinz, & B. Hommel (Eds.), Common mechanisms in perception and action: Attention and performance ( Vol. XIX , pp. 266–285). Oxford: Oxford University Press] have shown a temporal attraction in the perceived times of actions and effects, but did directly not study the relation between them. In three experiments, time estimates of an interval between an action and its subsequent sensory effect were obtained. The actions were either voluntary key press actions performed by the participant or kinematically identical movements applied passively to the finger. The effects were either auditory or visual events or a passive movement induced to another finger. The results first indicated a shortening of the interval between one’s own voluntary action and a subsequent effect, relative to passive movement conditions. Second, intervals initiated by observed movements, either of another person or of an inanimate object, were always perceived like those involving passive movements of one’s own body, and never like those involving active movements. Third, this binding effect was comparable for auditory, somatic and visual effects of action. Our results provide the first direct evidence that agency involves a generalisable relation between actions and their consequences, and is triggered by efferent motor commands. <s> BIB004 </s> Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> The Sense of Agency during Passive Observation of Other Humans <s> Recent research on human agency suggests that intentional causation is associated with a subjective compression in the temporal interval between actions and their effects. That is, intentional movements and their causal effects are perceived as closer together in time than equivalent unintentional movements and their causal effects. This so-called intentional binding effect is consistently found for one’s own self-generated actions. It has also been suggested that intentional binding occurs when observing intentional movements of others. However, this evidence is undermined by limitations of the paradigm used. In the current study we aimed to overcome these limitations using a more rigorous design in combination with functional Magnetic Resonance Imaging (fMRI) to explore the neural underpinnings of intentional binding of observed movements. In particular, we aimed to identify brain areas sensitive to the interaction between intentionality and causality attributed to the observed action. Our behavioral results confirmed the occurrence of intentional binding for observed movements using this more rigorous paradigm. Our fMRI results highlighted a collection of brain regions whose activity was sensitive to the interaction between intentionality and causation. Intriguingly, these brain regions have previously been implicated in the sense of agency over one’s own movements. We discuss the implications of these results for intentional binding specifically, and the sense of agency more generally. <s> BIB005 </s> Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> The Sense of Agency during Passive Observation of Other Humans <s> Sense of agency is the way in which we understand the causal relationships between our actions and sensory events. Agency is implicitly measured using intentional binding paradigms, where voluntary self-made actions and consequential sensory events are perceived as shifted closer together in time. However, a crucial question remains as to how we understand the relationship between others’ actions and sensory events. Do we use similar binding processes as for our own actions? Previous attempts to investigate this phenomenon in others’ have reached no clear consensus. Therefore, in an attempt to understand how we attribute the causal relationships between others’ actions and sensory events, we investigated intentional binding in others’ actions using an interval estimation paradigm. In a first experiment participants were required to make a button-press response to indicate the perceived interval between a self-made action and a tone, between a closely matched observed action and tone, and between two tones. For both self-made and observed actions, we found a significant perceived shortening of the interval between the actions and tones as compared with the interval between two tones, thus intentional binding was found for both self-made and observed actions. In a second experiment we validated the findings of the first by contrasting the perceived intervals between an observed action and tone with a matched visual–auditory stimulus and a tone. We again found a significant perceived shortening of the interval for observed action compared with the closely matched visual–auditory control stimulus. The occurrence of intentional binding when observing an action suggests we use similar processes to make causal attributions between our own actions, others’ actions, and sensory events. <s> BIB006 </s> Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> The Sense of Agency during Passive Observation of Other Humans <s> The subjective experience of controlling events in the environment alters the perception of these events. For instance, the interval between one’s own actions and their consequences is subjectively compressed—a phenomenon known as intentional binding. In two experiments, we studied intentional binding in a social setting in which actions of one agent prompted a second agent to perform another action. Participants worked in pairs and were assigned to a “leader” and a “follower” role, respectively. The leader’s key presses triggered (after a variable interval) a tone and this tone served as go signal for the follower to perform a keypress as well. Leaders and followers estimated the interval between the leader’s keypress and the following tone, or the interval between the tone and the follower’s keypress. The leader showed reliable intentional binding for both intervals relative to the follower’s estimates. These results indicate that human agents experience a pre-reflective sense of agency for genuinely social consequences of their actions. <s> BIB007 </s> Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> The Sense of Agency during Passive Observation of Other Humans <s> Every day we make attributions about how our actions and the actions of others cause consequences in the world around us. It is unknown whether we use the same implicit process in attributing causality when observing others' actions as we do when making our own. The aim of this research was to investigate the neural processes involved in the implicit sense of agency we form between actions and effects, for both our own actions and when watching others' actions. Using an interval estimation paradigm to elicit intentional binding in self-made and observed actions, we measured the EEG responses indicative of anticipatory processes before an action and the ERPs in response to the sensory consequence. We replicated our previous findings that we form a sense of implicit agency over our own and others' actions. Crucially, EEG results showed that tones caused by either self-made or observed actions both resulted in suppression of the N1 component of the sensory ERP, with no difference in suppression between consequences caused by observed actions compared with self-made actions. Furthermore, this N1 suppression was greatest for tones caused by observed goal-directed actions rather than non-action or non-goal-related visual events. This suggests that top-down processes act upon the neural responses to sensory events caused by goal-directed actions in the same way for events caused by the self or those made by other agents. <s> BIB008
Even when no common goal is shared, an individual can have a sense of agency during the observation of other-generated actions. Indeed, the activation of the observer's predictive systems links the action of the other to the observer's own motor system leading to a sense of agency enhancement. Thus, several studies have found IB phenomena for observed actions initiated by another person than the participant when this participant was not involved in the production of the outcome at all (Wohlschläger et al., 2003a,b; BIB005 BIB006 BIB007 BIB008 . For example, using an explicit judgment methodology, Wegner et al. (2004, experiment 1 and 2) have shown that participants reported a higher degree of vicarious sense of agency when they were consistently primed about the on-going observed action compared to when they were not BIB002 . In their experiment, the participants were paired with helpers. Both participants and helpers wore headphones. Hand helpers were told that they would hear a sequence of instructions on what hand actions to make over the headphones, while participants were told that they might or might not hear anything over their headphones and that whatever was heard might or might not relate to the actions of the helper. Then, the participants had to evaluate with a Likert scale their feeling of vicariant control over the helper's actions. The results showed that when the participants were correctly primed by headphone instructions about the helper's action, they rated vicarious control over the observed action higher than when they received prior incorrect information. Such a finding indicates that motor intention understanding-mainly achieved through the forward model-is engaged in the feeling of vicariant control. In BIB001 's experiment, participants were placed in front of a lever that triggered a tone 250 ms after being pushed on. There were two conditions involving humans. In the self-action condition, participants had to press the lever at the time of their own choice and in the otheraction condition participants observed the experimenter press the lever at the time of his choice. In both conditions, participants were asked to estimate the onset time of the lever press. The results showed that the perceived onset time of the action in the self-action condition was perceived in a similar fashion as in the other-action condition. Hence, the participants made IB independently of the generator of the action. This result emphasized that self-generated actions and observed othergenerated actions are experienced similarly. The authors argued that the conscious experience of action was shared out across agents through the neural network involved both in action execution and action understanding BIB001 . It is possible that the other-generated action was simulated in the observer's predictive system so that a high level of congruency between the predicted state derived from the efference copy and the estimated real state generated by the real movement observation occurred. Note should be taken that other studies using a similar paradigm failed to found binding effect during action observation BIB003 BIB004 . However, in BIB004 's study, the authors have implemented three different delays between the onset of the action and the onset of the tone (200, 250, and 300 ms), making predictability less important compared to the study of BIB001 where there was only one delay. According to BIB004 , efferent information plays a key role in individual's sense of agency and the IB for other-generated action is an artifact from high predictable delays. Still, an ERP study conducted by BIB008 has supported the idea of a common processing of self-generated and observed other-generated actions. In their experiment, participants had to press a key at the moment of their own choice or to observe a video where someone else was doing the same action. The key presses triggered a tone after a certain delay. In the control condition, there was no key press but the tone was presented twice, each presentation separated by a certain delay. For all conditions, participants had to estimate the perceived temporal interval between the first and the second event. The electrical activity of the participants' brain was recorded all along. Data showed that participants displayed IB between their own action and the subsequent tone as well as the delay between the observed action and the subsequent tone. For the control condition (externally-triggered tones), the delay between the two tones was overestimated. In addition, authors also used electroencephalography to measure the N1 wave suppression which is a mechanism associated with sensory attenuation that is considered as another implicit indicator of the sense of agency. The amplitude of the N1 component was reduced during the perception of the self-generated tone to the same extent that during the perception of the other-generated tone. For the control condition, N1 suppression was enhanced during the perception of the second tone compared to the first one because the sensory effect had already been heard once. To conclude, N1 suppression does occur also when hearing a sound that has been generated by another observed human BIB008 . These results are supported by the study of BIB005 . Indeed, using fMRI the authors have shown that the hemodynamic response of the cerebral areas underlying the sense of self-agency was similar for self-generated actions and observed other-generated actions BIB005 . Investigations have also focused on the effects of social variables on the sense of agency BIB007 . In BIB007 's study, participants were paired. One assumed a leader role and the other a follower role. The leader had to press a key at the moment of his or her own choice and the key press triggered a tone after a certain delay (interval 1). This tone served as a go-signal for the follower to press his or her own key (interval 2). The follower's key press could trigger a tone after a random delay (interval 3) or no tone at all. Both the leader and the follower had to verbally judge the interval lengths. The results showed that the leader's interval estimations were always shorter than the follower's interval estimations, meaning that the leaders always made more IB than the followers. In addition, as the initiator of the action, the leader made IB while the follower, as the observer, did not (interval 1). For the interval 2 estimation, the leader made IB for the follower's action but the follower did not. Hence, leaders' sense of agency does not only concern their own actions and their adjacent effect but also predictable actions of other agents. Finally, when the follower's key press generated a sensory consequence, the temporal interval estimations (interval 3) were similar for the leader and the follower: no participant made IB. That is, the follower never experienced a sense of agency neither over his or her own action and their effects nor over those of the leader. These different studies emphasize the importance of the predictive mechanisms in human-human interaction. The ability to predict appears as a fundamental component for both understanding and coordinating with others, but also a core component in our feeling of control in joint action. Interesting issues stem from the growing role of human machine interaction: can we take benefits from our predictive mechanisms when interacting with automated artificial agent?