Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> Predictive Systems for the Sense of Self-agency of Individual Actions <s> Abstract Several recently developed philosophical approaches to the self promise to enhance the exchange of ideas between the philosophy of the mind and the other cognitive sciences. This review examines two important concepts of self: the ‘minimal self', a self devoid of temporal extension, and the ‘narrative self', which involves personal identity and continuity across time. The notion of a minimal self is first clarified by drawing a distinction between the sense of self-agency and the sense of self-ownership for actions. This distinction is then explored within the neurological domain with specific reference to schizophrenia, in which the sense of self-agency may be disrupted. The convergence between the philosophical debate and empirical study is extended in a discussion of more primitive aspects of self and how these relate to neonatal experience and robotics. The second concept of self, the narrative self, is discussed in the light of Gazzaniga's left-hemisphere ‘interpreter' and episodic memory. Extensions of the idea of a narrative self that are consistent with neurological models are then considered. The review illustrates how the philosophical approach can inform cognitive science and suggests that a two-way collaboration may lead to a more fully developed account of the self. <s> BIB001 </s> Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> Predictive Systems for the Sense of Self-agency of Individual Actions <s> The present study is aimed at identifying the neural correlates of two kinds of attribution: experiencing oneself as the cause of an action (the sense of agency) or experiencing another person as being the cause of that action. The experimental conditions were chosen so that they differed only in their requirement to at- tribute an action to another person or to oneself. The same motor task and the same visual stimuli were used in the experimental conditions. Subjects used a joystick to drive a circle along a T-shaped path. They were told that the circle would be driven either by themselves or by the experimenter. In the former case subjects were requested to drive the circle, to be aware that they drove the circle, and thus to mentally attribute the action seen on the screen to themselves. In the latter case they were also requested to perform the task, but they were aware that action seen on the screen was driven by the experimenter. In accord with previous studies, the results showed that being aware of causing an action was associated with activation in the anterior insula, whereas being aware of not caus- ing the action and attributing it to another person was associated with activation in the inferior parietal cor- tex. These two regions are involved in the perception of complex representations of the self and of its inter- actions with the external world. We suggest that the anterior insula is concerned with the integration of all the concordant multimodal sensory signals associated with voluntary movements. The inferior parietal cor- tex, in contrast, represents movements in an allocen- tric coding system that can be applied to the actions of others as well as the self. © 2002 Elsevier Science (USA) <s> BIB002 </s> Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> Predictive Systems for the Sense of Self-agency of Individual Actions <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> BIB003 </s> Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> Predictive Systems for the Sense of Self-agency of Individual Actions <s> Patients with delusions of control are abnormally aware of the sensory consequences of their actions and have difficulty with on-line corrections of movement. As a result they do not feel in control of their movements. At the same time they are strongly aware of the action being intentional. This leads them to believe that their actions are being controlled by an external agent. In contrast, the normal mark of the self in action is that we have very little experience of it. Most of the time we are not aware of the sensory consequences of our actions or of the various subtle corrections that we make during the course of goal-directed actions. We know that we are agents and that we are successfully causing the world to change. But as actors we move through the world like shadows glimpsed only occasional from the corner of an eye. <s> BIB004 </s> Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> Predictive Systems for the Sense of Self-agency of Individual Actions <s> It is proposed that knowledge of motor commands is used to distinguish self-generated sensation from externally generated sensation. In this paper, we show that the sense of self-agency, that is the sense that I am the one who is generating an action, largely depends on the degree of discrepancy resulting from comparison between the predicted and actual sensory feedback. In Experiment 1, the sense of self-agency was reduced when the presentation of the tone was unpredictable in terms of timing and its frequency, although in fact the tone was self-produced. In Experiment 2, the opposite case was found to occur. That is, participants experienced illusionary sense of self-agency when the externally generated sensations happened to match the prediction made by forward model. In Experiment 3, the sense of self-agency was reduced when there was a discrepancy between the predicted and actual sensory consequences, regardless of presence or absence of a discrepancy between the intended and actual consequences of actions. In all the experiments, a discrepancy between the predicted and actual feedback had no effects on sense of self-ownership, that is the sense that I am the one who is undergoing an experience. These results may suggest that both senses of self are mutually independent. <s> BIB005 </s> Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> Predictive Systems for the Sense of Self-agency of Individual Actions <s> Abstract The sense of agency is a central aspect of human self-consciousness and refers to the experience of oneself as the agent of one’s own actions. Several different cognitive theories on the sense of agency have been proposed implying divergent empirical approaches and results, especially with respect to neural correlates. A multifactorial and multilevel model of the sense of agency may provide the most constructive framework for integrating divergent theories and findings, meeting the complex nature of this intriguing phenomenon. <s> BIB006 </s> Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> Predictive Systems for the Sense of Self-agency of Individual Actions <s> Abstract There is an increasing amount of empirical work investigating the sense of agency, i.e. the registration that we are the initiators of our own actions. Many studies try to relate the sense of agency to an internal feed-forward mechanism, called the “comparator model”. In this paper, we draw a sharp distinction between a non-conceptual level of feeling of agency and a conceptual level of judgement of agency. By analyzing recent empirical studies, we show that the comparator model is not able to explain either. Rather, we argue for a two-step account: a multifactorial weighting process of different agency indicators accounts for the feeling of agency, which is, in a second step, further processed by conceptual modules to form an attribution judgement. This new framework is then applied to disruptions of agency in schizophrenia, for which the comparator model also fails. Two further extensions are discussed: We show that the comparator model can neither be extended to account for the sense of ownership (which also has to be differentiated into a feeling and a judgement of ownership) nor for the sense of agency for thoughts. Our framework, however, is able to provide a unified account for the sense of agency for both actions and thoughts. <s> BIB007 </s> Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> Predictive Systems for the Sense of Self-agency of Individual Actions <s> We investigate the processes underlying the feeling of control over one's actions ("sense of agency"). Sense of agency may depend on internal motoric signals, and general inferences about external events. We used priming to modulate the sense of agency for voluntary and involuntary movements, by modifying the content of conscious thought prior to moving. Trials began with the presentation of one of two supraliminal primes, which corresponded to the effect of a voluntary action participants subsequently made. The perceived interval between movement and effect was used as an implicit measure of sense of agency. Primes modulated perceived intervals for both voluntary and involuntary movements, but the modulation was greatest for involuntary movements. A second experiment showed that this modulation depended on prime-movement (temporal) contiguity. We propose that sense of agency is based on a combination of internal motoric signals and external sensory evidence about the source of actions and effects. <s> BIB008 </s> Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> Predictive Systems for the Sense of Self-agency of Individual Actions <s> The sense of agency is the experience of being the origin of a sensory consequence. This study investigates whether contextual beliefs modulate low-level sensorimotor processes which contribute to the emergence of the sense of agency. We looked at the influence of causal beliefs on 'intentional binding', a phenomenon which accompanies self-agency. Participants judged the onset-time of either an action or a sound which followed the action. They were induced to believe that the tone was either triggered by themselves or by somebody else, although, in reality, the sound was always triggered by the participants. We found that intentional binding was stronger when participants believed that they triggered the tone, compared to when they believed that another person triggered the tone. These results suggest that high-level contextual information influences sensorimotor processes responsible for generating intentional binding. <s> BIB009 </s> Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> Predictive Systems for the Sense of Self-agency of Individual Actions <s> Sense of agency (SoA) is a compelling but fragile experience that is augmented or attenuated by internal signals and by external cues. A disruption in SoA may characterise individual symptoms of mental illness such as delusions of control. Indeed, it has been argued that generic SoA disturbances may lie at the heart of delusions and hallucinations that characterise schizophrenia. A clearer understanding of how sensorimotor, perceptual and environmental cues complement, or compete with, each other in engendering SoA may prove valuable in deepening our understanding the agency disruptions that characterise certain focal neurological disorders and mental illnesses. Here we examine the integration of SoA cues in health and illness, describing a simple framework of this integration based on Bayesian principles. We extend this to consider how alterations in cue integration may lead to aberrant experiences of agency. <s> BIB010 </s> Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> Predictive Systems for the Sense of Self-agency of Individual Actions <s> Intentional binding refers to the fact that when a voluntary action produces a sensory outcome, action and outcome are perceived as being closer together in time. This phenomenon is often attributed, at least partially, to predictive motor mechanisms. However, previous studies failed to unequivocally attribute intentional binding to these mechanisms, since the contrasts that have been used to demonstrate intentional binding covered not only one but two processes: temporal control and motor identity prediction. In the present study we aimed to isolate the respective role of each of these processes in the emergence of intentional binding of action-effects. The results show that motor identity prediction does not modulate intentional binding of action-effects. Our findings cast doubts on the assumption that intentional binding of action effects is linked to internal forward predictive process. <s> BIB011 </s> Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> Predictive Systems for the Sense of Self-agency of Individual Actions <s> Sensory attenuation refers to the observation that self-generated stimuli are attenuated, both in terms of their phenomenology and their cortical response compared to the same stimuli when generated externally. Accordingly, it has been assumed that sensory attenuation might help individuals to determine whether a sensory event was caused by themselves or not. In the present study, we investigated whether this dependency is reciprocal, namely whether sensory attenuation is modulated by prior beliefs of authorship. Participants had to judge the loudness of auditory effects that they believed were either self-generated or triggered by another person. However, in reality, the sounds were always triggered by the participants' actions. Participants perceived the tones' loudness attenuated when they believed that the sounds were self-generated compared to when they believed that they were generated by another person. Sensory attenuation is considered to contribute to the emergence of people's belief of authorship. Our results suggest that sensory attenuation is also a consequence of prior belief about the causal link between an action and a sensory change in the environment. <s> BIB012 </s> Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> Predictive Systems for the Sense of Self-agency of Individual Actions <s> ‘‘Sense of agency’’ refers to the feeling of controlling an externalevent through one’s own action. On one inﬂuential view, sense ofagency is inferred after an action, by ‘‘retrospectively’’ comparingactual effects of actions against their intended effects. In contrast,a ‘‘prospective’’ component of agency, generated during actionselection, and in advance of knowing the actual effect, hasreceived less attention. Here, we used functional magneticresonance imaging to investigate prospective contributions ofaction selection processes to sense of agency. To do so, wedissociated action selection processes from action--outcomematching, by subliminally priming responses to a target. We foundthat participants experienced greater control over action effectswhen the action was compatibly versus incompatibly primed. Thus,compatible primes facilitated action selection processing, in turnboosting sense of agency over a subsequent effect. This pro-spective contribution of action selection processes to sense ofagency was accounted for by exchange of signals acrossa prefrontal--parietal network. Speciﬁcally, we found that theangular gyrus (AG) monitors signals relating to action selection indorsolateral prefrontal cortex, to prospectively inform subjectivejudgments of control over action outcomes. Online monitoring ofthese signals by AG might provide the subject with a subjectivemarker of volition, prior to action itself.Keywords: action selection, agency, angular gyrus, dorsolateral prefrontalcortex, fMRIIntroductionImagine you are the manager of a busy factory. You shouldexperience a strong feeling that your actions profoundlyinﬂuence what happens throughout the factory. But wheredoes this feeling come from, and when does it occur? Do youinfer your degree of control only retrospectively, when you seethe ﬁnished product ready for shipping or even the quarterlysales ﬁgures? Or is it prospective? Does the ease and claritywith which you make strategic decisions already give youa feeling of control before you see actual results?This everyday example illustrates the contrast between 2neuroscientiﬁc views of what has often been called ‘‘sense ofagency,’’ that is, the subjective experience of controlling one’sown actions and, through them, events in the outside world(Haggard and Tsakiris 2009). Much current research empha-sizes this sense of control arises when external events areconsistent with internal predictions of action outcomes(Blakemore et al. 1998; Farrer et al. 2008; Moore and Haggard2008; Sato 2009; Nahab et al. 2011) or are generally consistentwith our intentions (Wegner 2002; Wegner et al. 2004). For,example, if I intend to turn on the light by pressing a switch,and the light then happens to come on, I am likely to feel that Icaused the light to come on. On this view, agency is inferred‘‘retrospectively,’’ after an action has been performed, based onthe external consequences of the action. On a neural level,many studies suggest that the angular gyrus (AG) computessense of agency by retrospectively matching the predictedeffects of action against its actual effects, resulting ina perturbed sense of agency when a mismatch occurs (Farrerand Frith 2002; Farrer et al. 2003, 2008).An alternative possibility, that sense of agency might bebased on ‘‘prospective’’ processes relating to actions one ‘‘will’’shortly perform, has received less attention. Yet, there is someevidence that people can prospectively judge agency bymonitoring their performance online, whilst doing the task,and irrespective of whether subsequent intended outcomesoccurred, or did not occur, as predicted (Metcalfe and Greene2007). Here, we explore whether this prospective sense ofcontrol may depend on internal processes of action selectionand preparation occurring ‘‘before’’ movement, even whenparticipants make retrospective judgments of agency. In linewith this assumption, we investigated whether AG, which hasbeen shown to compute ‘‘retrospective’’ agency by monitoringaction outcomes (Farrer et al. 2003, 2008), may also code fora prospective sense of control by monitoring action selectionprocesses in advance of the action itself and independently ofaction outcomes.To do this, we dissociated the processes of action selectionfrom the match between actions and outcome, by subliminallypriming responses to a target. Previous research has shown thataction selection is easier (faster and less error prone) whenpreceding subliminal primes are compatible with a motorresponse to a target stimulus than when they are incompatible(Vorberg et al. 2003). Interestingly, this ﬂuency of actionselection is also relevant to sense of control. Thus, in onerecent study (Wenke et al. 2010), participants reportedstronger sense of control over action outcomes when theirresponses to a target cue had previously been subliminallyprimed by a compatible, as opposed to an incompatible, prime.Importantly, this was not simply due to the predictability of theaction outcomes, since outcome stimuli (colored patches inthis experiment) following compatible and incompatibleprimes were equally predictable. Rather, the stronger experi-ence of control when subliminal prime and target cue werecompatible could only be explained by the ‘‘ﬂuency’’ of actionselection processes—that is, by an internal signal inﬂuenced bysubliminal priming, and experienced before the action wasmade. Thus, compatible primes facilitated action selectionprocessing by making selection processes ‘‘ﬂuent.’’ Increasedﬂuency of selection in turn boosted sense of agency over actioneffects (Wenke et al. 2010). <s> BIB013 </s> Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> Predictive Systems for the Sense of Self-agency of Individual Actions <s> The experience of agency, i.e., the registration that I am the initiator of my actions, is a basic and constant underpinning of our interaction with the world. Whereas several accounts have underlined predictive processes as the central mechanism (e.g. the comparator model by C.Frith), others emphasized postdictive inferences (e.g. post hoc inference account by D. Wegner). Based on increasing evidence that both predictive and postdictive processes contribute to the experience of agency, we here present a unifying but at the same time parsimonious approach that reconciles these accounts: predictive and postdictive processes are both integrated by the brain according to the principles of optimal cue integration. According to this framework, predictive and postdictive processes each serve as authorship cues that are continuously integrated and weighted depending on their availability and reliability in a given situation. Both sensorimotor and cognitive signals can serve as predictive cues (e.g. internal predictions based on an efferency copy of the motor command, or cognitive anticipations based on priming). Similarly, other sensorimotor and cognitive cues can each serve as post-hoc cues (e.g. visual feedback of the action or the affective valence of the action outcome). Integration and weighting of these cues might not only differ between contexts and individuals, but also between different subject and disease groups. For example, schizophrenia patients with delusions of influence seem to rely less on (probably imprecise) predictive motor signals of the action and more on post-hoc action cues like e.g. visual feedback and, possibly, the affective valence of the action outcome. Thus, the framework of optimal cue integration offers a promising approach that directly stimulates a wide range of experimentally testable hypotheses on agency processing in different subject groups. <s> BIB014 </s> Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> Predictive Systems for the Sense of Self-agency of Individual Actions <s> Sense of agency refers to the feeling of controlling an external event through one’s own action. On one influential view, agency depends on how predictable the consequences of one’s action are, getting stronger as the match between predicted and actual effect of an action gets closer. Thus, sense of agency arises when external events that follow our action are consistent with predictions of action effects made by the motor system while we perform or simply intend to perform an action. According to this view, agency is inferred retrospectively, after an action has been performed and its consequences are known. In contrast, little is known about whether and how internal processes involved in the selection of actions may influence subjective sense of control, in advance of the action itself, and irrespective of effect predictability. In this article, we review several classes of behavioural and neuroimaging data suggesting that earlier processes, linked to fluency of action selection, prospectively contribute to sense of agency. These findings have important implications for better understanding human volition and abnormalities of action experience. <s> BIB015 </s> Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> Predictive Systems for the Sense of Self-agency of Individual Actions <s> The sense of agency refers to the feeling that we are in control of our actions and, through them, of events in the outside world. Much research has focused on the importance of retrospectively matching predicted and actual action outcomes for a strong sense of agency. Yet, recent studies have revealed that a metacognitive signal about the fluency of action selection can prospectively inform our sense of agency. Fluent, or easy, action selection leads to a stronger sense of agency over action outcomes than dysfluent, or difficult, selection. Since these studies used subliminal priming to manipulate action selection, it remained unclear whether supraliminal stimuli affecting action selection would have similar effects. We used supraliminal flankers to manipulate action selection in response to a central target. Experiment 1 revealed that conflict in action selection, induced by incongruent flankers and targets, led to reduced agency ratings over an outcome that followed the participant's response, relative to neutral and congruent flanking conditions. Experiment 2 replicated this result, and extended it to free choice between alternative actions. Finally, Experiment 3 varied the stimulus onset asynchrony (SOA) between flankers and target. Action selection performance varied with SOA. Agency ratings were always lower in incongruent than congruent trials, and this effect did not vary across SOAs. Sense of agency is influenced by a signal that tracks conflict in action selection, regardless of the visibility of stimuli inducing conflict, and even when the timing of the stimuli means that the conflict may not affect performance. <s> BIB016
The sense of self-agency refers to the pre-reflexive experience of being in control of voluntary performed actions BIB001  . Strong links have been made between the motor internal comparison processes and the sense of self-agency BIB001  . The claim is that the quality of the match between a) the predicted state generated by predictors from the efference copy and the estimated real state generated by the real movement (Figure 1, comparison 3) and between b) the desired state and the predicted state (Figure 1 , comparison 2) underlie the sense of self-agency BIB004 BIB005 BIB006 BIB010 . Specifically, comparison 3 has been proposed to be mainly involved in self-agency attribution: sensory feedback that is congruent with the internal prediction will be self-attributed, while incongruent feedback will be attributed to external sources. The more incongruent the two signals are, the less sense of agency will the agent experience. For example, individuals misattribute self-generated sensory effects to an external source when an unexpected longer temporal delay follows their action BIB005 . Additionally, BIB004 proposed that comparison 2 was involved in the feeling of being in control of a given action because it allows for on-line adjustments of our own actions BIB004 . Thus, the signals generated by both comparisons would contribute to an individual's sense of self-agency. Note that we acknowledge some limitations to the CM to explain by itself individual's sense of self-agency shaping BIB007 BIB011  . Indeed, the sense of agency may result from the dynamic integration of multifactorial sensorimotor cues (feed-forward cues, proprioception and sensory feedback) and circumstantial cues (intentions, thoughts, social and contextual cues) BIB007 BIB010 . For example, some authors have shown that when participants were induced the false thought that they were not the initiator of a tone but that a confederate presented as a genuine participant was, they experience less sense of agency (manifested by less IB when they were asked to judge the onset of the tone or less sensory attenuation when they were asked to judge the loudness of the tone) compared to when they thought that they were effectively the initiator of the sensory effect, even if in both cases it was the participant who had triggered the tone BIB009 BIB012 . However, this does not discredit the validity of the CM and we assume that sensorimotor predictive processes play a key role in the sense of self-agency of individual actions. Given that sensory feedback is needed in the CM (implying the action has been done), it has been considered as a retrospective process by several authors BIB002 BIB007 BIB013 BIB015 . Yet, in line with BIB014 , we consider that the CM is essentially a prospective process for the sense of agency because the predictive mechanism that occurs before action onset (i.e., the predictions about the sensory consequences of the action made through the efference copy) plays a crucial role in the model BIB014 . Despite these divergent views, predictive mechanisms are still considered as a key component of the sense of agency. Moreover, the effect of action selection on human sense of agency has also been considered as an argument to consider the sense of agency as a prospective process BIB013 BIB015 . Indeed, when action selection is easy, the sense of selfagency becomes stronger compared to conflictual action selection and as a consequence, it prospectively informs the sense of agency BIB015 BIB016 . For example, using an Eriksen flanker task, BIB016 showed that participants' judgments of control were higher on congruent trials compared to neutral and incongruent ones BIB016 . The participants were presented a central target letter (S or H) surrounded by four non-target letters (two on the left and two on the right). Participants had to press a left key when the central target letter was an "S" and a right key when the central target was an "H." The flanked letters could be congruent or incongruent with the central target. The detailed procedure for one trial is described on Figure 2 . Because they were similar to the target, congruent distractors were meant to facilitate action selection whereas incongruent distractors were meant to induce a conflict in action selection as they were associated with the alternative action. Each key press triggered a specific sensory consequence. Participants had to report their feeling of control over the apparition of the sensory consequence on a Likert scale. Participants' reaction times were faster on congruent trials compared to incongruent trials. This facilitation effect during congruent trials went with higher explicit judgment of control compared to incongruent trials, thus demonstrating that changes in the flow of an ongoing action can modify an individual's sense of agency. Similarly, consistent priming about the sensory effects as well as about the ongoing action enhances participants' sense of self-agency BIB003 BIB008 BIB016 . Interestingly, such predictive mechanisms seem to be involved also in social interactions with human peers.