We investigated how motor agency in the voluntary control of body movement influences body awareness. In the Rubber Hand Illusion , synchronous tactile stimulation of a rubber hand and the participant’s hand leads to a feeling of the rubber hand being incorporated in the participant’s own body. One quantifiable behavioural correlate of the illusion is an induced shift in the perceived location of the participant’s hand towards the rubber hand. Previous studies showed that the induced changes in body awareness are (...) local and fragmented: the proprioceptive drift is largely restricted to the stimulated finger. In the present study, we investigated whether active and passive movements, rather than tactile stimulation, would lead to similarly fragmented body awareness. Participants watched a projected image of their hand under three conditions: active finger movement, passive finger movement, and tactile stimulation. Visual feedback was either synchronous or asynchronous with respect to stimulation of the hand. A significant overall RHI, defined as greater drifts following synchronous than asynchronous stimulation, was found in all cases. However, the distribution of the RHI across stimulated and non-stimulated fingers depended on the kind of stimulation. Localised proprioceptive drifts, specific to the stimulated finger, were found for tactile and passive stimulation. Conversely, during active movement of a single digit, the proprioceptive drifts were not localised to that digit, but were spread across the whole hand. Whereas a purely proprioceptive sense of body-ownership is local and fragmented, the motor sense of agency integrates distinct body-parts into a coherent, unified awareness of the body. (shrink)

We investigate the processes underlying the feeling of control over one’s actions . 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 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. (shrink)

Intentional action involves both a series of neural events in the motor areas of the brain, and also a distinctive conscious experience that ''I'' am the author of the action. This paper investigates some possible ways in which these neural and phenomenal events may be related. Recent models of motor prediction are relevant to the conscious experience of action as well as to its neural control. Such models depend critically on matching the actual consequences of a movement against its internally (...) predicted effects. However, it remains unclear whether our conscious experience of action depends on a precise matching process, or a retrospective inference that ''I'' must have been responsible for a particular event. We report an experiment in which normal subjects judged the perceived time of either intentional actions, involuntary movements, or subsequent effects (auditory tones) of these. We found that the subject's intention to produce the auditory tone produced an intentional binding between the perceived times of the subject's action and the tone. However, if the intention was interrupted by an imposed involuntary movement, followed by the identical tone, no such binding occurred. The phenomenology of intentional action requires an appropriate predictive link between intentions and effects, rather than a retrospective inference that ''I'' caused the effect. (shrink)

When subjects view stimulation of a rubber hand while feeling congruent stimulation of their own hand, they may come to feel that the rubber hand is part of their own body. This illusion of body ownership is termed ‘Rubber Hand Illusion’ . We investigated sensitivity of RHI to spatial mismatches between visual and somatic experience. We compared the effects of spatial mismatch between the stimulation of the two hands, and equivalent mismatches between the postures of the two hands. We created (...) the mismatch either by adjusting stimulation or posture of the subject’s hand, or, in a separate group of subjects, by adjusting stimulation or posture of the rubber hand. The matching processes underlying body ownership were asymmetrical. The illusion survived small changes in the subject’s hand posture, but disappeared when the same posture transformations were applied to the rubber hand. Mismatch between the stimulation delivered to the subject’s hand and the rubber hand abolished the illusion. The combination of these two situations is of particular interest. When the subject’s hand posture was slightly different from the rubber hand posture, the RHI remained as long as stimulation of the two hands was congruent in a hand-centred spatial reference frame, even though the altered posture of the subject’s hand meant that stimulation was incongruent in external space. Conversely, the RHI was reduced when the stimulation was incongruent in hand-centred space but congruent in external space. We conclude that the visual–tactile correlation that causes the RHI is computed within a hand-centred frame of reference, which is updated with changes in body posture. Current sensory evidence about what is ‘me’ is interpreted with respect to a prior mental body representation. (shrink)

The sense of agency is a basic feature of our subjective experience. Experimental studies usually focus on either its attributional aspects or on its motoric aspects. 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.. Action, binding and awareness. In W. Prinz, & B. Hommel, Common mechanisms in perception and action: Attention and performance. 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. (shrink)

The experience of causation is a pervasive product of the human mind. Moreover, the experience of causing an event alters subjective time: actions are perceived as temporally shifted towards their effects [Haggard, P., Clark, S., & Kalogeras, J.. Voluntary action and conscious awareness. Nature Neuroscience, 5, 382-385]. This temporal shift depends partly on advance prediction of the effects of action, and partly on inferential "postdictive" explanations of sensory effects of action. We investigated whether a single factor of statistical contingency could (...) explain both these aspects of causal experience. We studied the time at which people perceived a simple manual action to occur, when statistical contingency indicated a causal relation between action and effect, and when no such relation was indicated. Both predictive and inferential "postdictive" shifts in the time of action depended on strong contingency between action and effect. The experience of agency involves a process of causal learning based on statistical contingency. (shrink)

The problem of free will lies at the heart of modern scientific studies of consciousness. An influential series of experiments by Libet has suggested that conscious intentions arise as a result of brain activity. This contrasts with traditional concepts of free will, in which the mind controls the body. A more recent study by Haggard and Eimer has further examined the relation between intention and brain processes, concluding that conscious awareness of intention is linked to the choice or selection of (...) a specific action, and not to the earliest initiation of action processes. The exchange of views in this paper further explores the relation between conscious intention and brain activity. (shrink)

In this paper, we introduce and defend the recurrent model for understanding bodily spatial phenomenology. While Longo, Azañón and Haggard (2010) propose a bottom-up model, Bermúdez (2017) emphasizes the top-down aspect of the information processing loop. We argue that both are only half of the story. Section 1 intro- duces what the issues are. Section 2 starts by explaining why the top- down, descending direction is necessary with the illustration from the ‘body-based tactile rescaling’ paradigm (de Vignemont, Ehrsson and Haggard, (...) 2005). It then argues that the bottom-up, ascending direction is also necessary, and substantiates this view with recent research on skin space and tactile field (Haggard et al., 2017). Section 3 discusses the model’s application to body ownership and bodily self-representation. Implications also extend to topics such as sense modality individuation (Macpherson, 2011), the constancy- based view of perception (Burge, 2010), and the perception/cognition divide (Firestone and Scholl, 2016). (shrink)

Sense of agency refers to the sense of initiating and controlling actions in order to influence events in the outside world. Recently, a distinction between implicit and explicit aspects of sense of agency has been proposed, analogous to distinctions found in other areas of cognition, notably learning. However, there is yet no strong evidence supporting separable implicit and explicit components of sense of agency. The so-called ‘Perruchet paradigm’ offers one of the few convincing demonstrations of separable implicit and explicit learning (...) systems. We adopted this approach to evaluate the implicit–explicit distinction in the context of a simple task in which outcomes were probabilistically caused by actions. In line with our initial predictions, we found evidence of a dissociation. We discuss the implications of this result for theories of sense of agency. (shrink)

The conscious feeling of exercising ‘free-will’ is fundamental to our sense of self. However, in some psychopathological conditions actions may be experienced as involuntary or unwilled. We have used suggestion in hypnosis to create the experience of involuntariness in normal participants. We compared a voluntary finger movement, a passive movement and a voluntary movement suggested by hypnosis to be ‘involuntary.’ Hypnosis itself had no effect on the subjective experience of voluntariness associated with willed movements and passive movements or on time (...) estimations of their occurrence. However, subjective time estimates of a hypnotically-suggested, ‘involuntary’ finger movement were more similar to those for passive movements than for voluntary movements. The experience of anomalous control is qualitatively and quantitatively different from the normal conscious experience of a similar act produced intentionally. The experience of anomalous control may be produced either by pathology, or, in our case, by suggestion. (shrink)

The experience of agency refers to the feeling that we control our own actions, and through them the outside world. In many contexts, sense of agency has strong implications for moral responsibility. For example, a sense of agency may allow people to choose between right and wrong actions, either immediately, or on subsequent occasions through learning about the moral consequences of their actions. In this study we investigate the relation between the experience of operant action, and responsibility for action outcomes (...) using the intentional binding effect as an implicit, quantitative measure related to sense of agency. We studied the time at which people perceived simple manual actions and their effects, when these actions were embedded in scenarios where their actions had unpredictable consequences that could be either moral or merely economic. We found an enhanced binding of effects back towards the actions that caused them, implying an enhanced sense of agency, in moral compared to non-moral contexts. We also found stronger binding for effects with severely negative, compared to moderately negative, values. A tight temporal association between action and effect may be a low-level phenomenal marker of the sense of responsibility. (shrink)

The concept of intention can do useful work in psychological theory. Many authors have insisted on a qualitative difference between prospective and intentions regarding their type of content, with prospective intentions generally being more abstract than immediate intentions. However, we suggest that the main basis of this distinction is temporal: prospective intentions necessarily occur before immediate intention and before action itself, and often long before them. In contrast, immediate intentions occur in the specific context of the action itself. Yet both (...) types of intention share a common purpose,namely that of generating the specific information required to transform an abstract representation of a goal-state into a concrete episode of instrumental action directed towards that goal. To this extent, the content of a prospective and of an immediate intention can actually be quite similar. The main distinction between prospective and immediate intentions becomes one of when, i.e., how early on, the episodic details of an action are planned. We propose that the conscious experience associated with intentional action comes from this process of fleshing out intentions with episodic details. (shrink)

Our perception of where touch occurs on our skin shapes our interactions with the world. Most accounts of cutaneous localisation emphasise spatial transformations from a skin-based reference frame into body-centred and external egocentric coordinates. We investigated another possible method of tactile localisation based on an intrinsic perception of ‘skin space’. The arrangement of cutaneous receptive fields (RFs) could allow one to track a stimulus as it moves across the skin, similarly to the way animals navigate using path integration. We applied (...) curved tactile motions to the hands of human volunteers. Participants identified the location midway between the start and end points of each motion path. Their bisection judgements were systematically biased towards the integrated motion path, consistent with the characteristic inward error that occurs in navigation by path integration. We thus showed that integration of continuous sensory inputs across several tactile RFs provides an intrinsic mechanism for spatial perception. (shrink)

Subjects estimated the time of intentions to perform an action, of the action itself, or of an auditory effect of the action. A perceptual attraction or binding effect occurred between actions and the effects that followed them. Judgements of intentions did not show this binding, suggesting they are represented independently of actions and their effects. In additional unpredictable judgement conditions, subjects were instructed only after each trial which of these events to judge, thus discouraging focussed attention to a specific event. (...) Stronger binding effects were found, with intention, action and effect fusing to a single central point in time. In a control task, subjects reported the time of the first or second tone in sequence. Tone sequences showed no binding at all when subjects knew in advance which tone to judge, but showed the same fusion as actions when the event to be judged was not predictable. Binding of actions and effects, but not of tone sequences, occurs pre-attentively, and automatically. The data are consistent with a reconstructive process, implemented after actions, which generates a coherent sense of agency. However, this process should only be triggered only when our actions make it appropriate. We suggest that this mechanism is triggered in advance by efferent processing. This conclusion was supported by a further study in deafferented subject IW. This subject showed the normal binding of a tone towards an action, although his experience of the action was of pre-motor, rather than peripheral origin. The experience of intentional action involves an interplay between pre-motor and reconstructive processes. (shrink)

The concept of self-generated action is controversial, despite extensive study of its neural basis. Why is this concept so troublesome? We analyse the concept of self-generated action as employed by and. There are two definitions of self-generated action; as operant action and as underdetermined action. The latter draws on subjective experience. Experiments on action awareness suggest that experience may not be a good guide for defining self-generated action. Nevertheless, we agree with Passingham and colleagues that self-generated actions exist distinct from (...) operant actions. But defining ‘self-generated’ by the degree of involvement of an endogenous process risks regress. We sketch an alternative account of self-generated action that tries to avoid these problems to make self-generated actions accessible to experimental science. (shrink)

The subjective feeling of free choice is an important feature of human experience. Experimental tasks have typically studied free choice by contrasting free and instructed selection of response alternatives. These tasks have been criticised, and it remains unclear how they relate to the subjective feeling of freely choosing. We replicated previous findings of the fMRI correlates of free choice, defined objectively. We introduced a novel task in which participants could experience and report a graded sense of free choice. BOLD responses (...) for conditions subjectively experienced as free identified a postcentral area distinct from the areas typically considered to be involved in free action. Thus, the brain correlates of subjective feeling of free action were not directly related to any established brain correlates of objectively-defined free action. Our results call into question traditional assumptions about the relation between subjective experience of choosing and activity in the brain’s so-called voluntary motor areas. (shrink)

Recent research has shown that human instrumental action is associated with systematic changes in time perception: The interval between a voluntary action and an outcome is perceived as shorter than the interval between a physically similar involuntary movement and an outcome. The study by, Ebert and Wegner suggests that this change in time perception is related to higher order agency experience. Notwithstanding certain issues arising from their study, which are discussed, we believe it offers validation of binding as a measure (...) of sense of agency. (shrink)

Introspectively, the awareness of actions includes the awareness of the intentions accompanying them. Therefore, the awareness of self-generated actions might be expected to differ from the awareness of other-generated actions to the extent that access to one's own and to other's intentions differs. However, we recently showed that the perceived onset times of self- vs. other-generated actions are similar, yet both are different from comparable events that are conceived as being generated by a machine. This similarity raises two interesting possibilities. (...) First we could infer the intentions of others from their actions. Second and more radically, we could equally infer our own intentions from the actions we perform rather than sense them. We present two new experiments which investigate the role of action effects in the awareness of self- and other-generated actions by means of measuring the estimated onset time. The results show that the presence of action effects is necessary for the similarity of awareness of self- and other-generated actions. (shrink)

It remains controversial whether touch is a truly spatial sense or not. Many philosophers suggest that, if touch is indeed spatial, it is only through its alliances with exploratory movement, and with proprioception. Here we develop the notion that a minimal yet important form of spatial perception may occur in purely passive touch. We do this by showing that the array of tactile receptive fields in the skin, and appropriately relayed to the cortex, may contain the same basic informational building (...) blocks that a creature navigating around its environment uses to build up a perception of space. We illustrate this point with preliminary evidence that perception of spatiotemporal patterns on the human skin shows some of the same features as spatial navigation in animals. We argue (a) that the receptor array defines a ‘tactile field’, (b) that this field exists in a minimal form in ‘skin space’, logically prior to any transformation into bodily or external spatial coordinates, and (c) that this field supports tactile perception without integration of concurrent proprioceptive or motor information. The basic cognitive elements of space perception may begin at lower levels of neural and perceptual organisation than previously thought. (shrink)

Appreciating human movement can be a powerful aesthetic experience. We have used apparent biological motion to investigate the aesthetic effects of three levels of movement representation: body postures, movement transitions and choreographic structure. Symmetrical and asymmetrical sequences of apparent movement were created from static postures, and were presented in an artificial grammar learning paradigm. Additionally, “good” continuation of apparent movements was manipulated by changing the number of movement path reversals within a sequence. In an initial exposure phase, one group of (...) participants saw only symmetrical sequences, while another group saw only asymmetrical sequences. In a subsequent test phase, both groups rated all sequences on an aesthetic evaluation scale. We found that posture, movement, and choreographic structure all influenced aesthetic ratings. Separate ratings for the static body postures presented individually showed that both groups preferred a posture that maximized spatial symmetry. Ratings for the experimental sequences showed that both groups gave higher ratings to symmetrical sequences with “good” continuation and lower ratings to sequences with many path reversals. Further, participants who had been initially familiarized with asymmetrical sequences showed increased liking for asymmetrical sequences, suggesting a structural mere exposure effect. Aesthetic preferences thus depend on body postures, apparent movement continuation and choreographic structure. We propose a hierarchical model of aesthetic perception of human movement with distinct processing levels for body postures, movements and choreographic structure. (shrink)

The concept of individual free will is difficult to reconcile with a materialist view of the brain. The debate over “free will” involves a series of several questions about the origin of human actions, and their resulting social, legal, and ethical implications. This article sets out the reasons that scientific questions regarding free will have important ethical and social consequences. It then considers the neuroscientific debate over whether a conscious experience of volition does or does not precede the brain's preparation (...) for action. It outlines that conscious volition is a consequence of brain activity, perhaps linked to the capacity to inhibit ongoing actions. A major objection to this view is reviewed, based on social psychological studies of unconscious determinants of behavior, and of attribution theory. Finally, some specific issues for neuroethical debate are suggested. (shrink)

The control of action has traditionally been described as "automatic". In particular, movement control may occur without conscious awareness, in contrast to normal visual perception. Studies on rapid visuomotor adjustment of reaching movements following a target shift have played a large part in introducing such distinctions. We suggest that previous studies of the relation between motor performance and perceptual awareness have confounded two separate dissociations. These are: (a) the distinction between motoric and perceptual representations, and (b) an orthogonal distinction between (...) conscious and unconscious processes. To articulate these differences more clearly, we propose a new measure of motor awareness, based on subjects' ability to reproduce the spatial details of reaching movements they have just made. Here we focus on the dissociation between motor awareness and perceptual awareness that may occur when subjects make rapid visuomotor adjustments to reaching movements following a target shift. In experiment 1, motor awareness was dissociated from perceptual awareness of a target shift during reaching movement. Participants' reproduction of movement endpoints following visuomotor adjustment was independent of whether they saw the target shift or not. Experiment 2 replicated this result, and further showed that neither motor awareness nor motor performance were disrupted by TMS over the parietal cortex. The neural mechanisms underlying motor awareness, and the implications for theories of consciousness, are discussed. (shrink)

Introspectively, the awareness of actions includes the awareness of the intentions accompanying them. Therefore, the awareness of self-generated actions might be expected to differ from the awareness of other-generated actions to the extent that access to one's own and to other's intentions differs. However, we recently showed that the perceived onset times of self- vs. other-generated actions are similar, yet both are different from comparable events that are conceived as being generated by a machine. This similarity raises two interesting possibilities. (...) First we could infer the intentions of others from their actions. Second and more radically, we could equally infer our own intentions from the actions we perform rather than sense them. We present two new experiments which investigate the role of action effects in the awareness of self- and other-generated actions by means of measuring the estimated onset time. The results show that the presence of action effects is necessary for the similarity of awareness of self- and other-generated actions. (shrink)

The “body image” is a putative mental representation of one’s own body, including structural and geometric details, as well as the more familiar visual and affective aspects. Very little research has investigated how we learn the structure of our own body, with most researchers emphasising the canonical visual representation of the body when we look at ourselves in a mirror. Here, we used non-visual self-touch in healthy participants to investigate the possibility that primary sensorimotor experience may influence cognitive representations of (...) one’s own body structure. Participants used the fingers of one hand , to touch the fingers of the other . A conflict between the experience of the active and passive hand was introduced by experimenter interleaving their fingers with the fingers of the participant’s passive hand. This led to the active hand experiencing that it touched more fingers than the passive hand felt it was being touched by. The effects on representation of body structure were assessed using an implicit measure based on Kinsbourne and Warrington’s ‘in-between task’. We found an underestimation of the number of fingers in the central part of the hand specifically linked to the experience of self-touch. This pattern of results corresponds to the experience of the passive hand, but not the active hand. Nevertheless, comparable reorganisation of fingers within the hand representation was found for both active and passive hands. We show that primary sensorimotor experience can modify the representation of body structure. This modification is driven by the passive experience of being touched, rather than by the active experience of touching. We believe this is the first experimental study of effects of self-touch on the mental representation of the body. (shrink)

Psychologists have traditionally approached phenomenology by describing perceptual states, typically in the context of vision. The control of actions has often been described as 'automatic', and therefore lacking any specific phenomenology worth studying. This article will begin by reviewing some historical attempts to investigate the phenomenology of action. This review leads to the conclusion that, while movement of the body itself need not produce a vivid conscious experience, the neural process of voluntary action as a whole has distinctive phenomenological consequences. (...) The remainder of the article tries to characterise this phenomenology. First, the planning of actions is often conscious, and can produce a characteristic executive mode of awareness. Second, our awareness of action often arises from the process of matching what we intended to do with what actually happened. Failures of this matching process lead to particularly vivid conscious experience, which we call 'error awareness'. These features of action phenomenology can be directly related to established models of motor control. This allows an important connection between phenomenology and neuroscience of action. Third, whereas perceptual phenomenology is normally seen as caused or driven by the sensory stimulus, a much more fluid model is required for phenomenology of action. Several experimental results suggest that phenomenology of action is partly a post hoc reconstruction, while others suggest that our awareness of action represents an integration of several processes at multiple levels of motor processing. Fourth, and finally, studies of the phenomenology of action, unlike those of perception, show a strong linkage between primary awareness and secondary awareness or self-consciousness: awareness of action is specifically and inextricably awareness of my action. We argue that the concepts of agency and of proprioaction are fundamental to this linkage. For these reasons, action represents a much more promising field than perception for attacking the problematic question of the relation between primary and secondary consciousness. Some promising directions for future research are indicated. (shrink)

This chapter explores the interaction between neuroscience and free will. First, it considers how freely willed actions should be defined. Second, it outlines current understanding of brain mechanisms preceding action, showing in what respects these mechanisms meet the philosophical criteria for freely willed action, and in what respects they do not. Finally, it concludes that the philosophical criteria themselves are based on two underlying psychological facts: human action involves complex mappings between environmental stimuli and goal-directed responses, and human action is (...) associated with a range of quasi-perceptual experiences, classically called ‘motor attention’. These facts lie at the heart of our concept of conscious free will, and are directly related to the recent evolutionary development of the brain's frontal lobes. (shrink)

Saccadic chronostasis refers to the subjective temporal lengthening of the first visual stimulus perceived after an eye movement. It has been quantified using a duration discrimination task. Most models of human duration discrimination hypothesise an internal clock. These models could explain chronostasis as a transient increase in internal clock speed due to arousal following a saccade, leading to temporal overestimation. Two experiments are described which addressed this hypothesis by parametrically varying the duration of the stimuli that are being judged. Changes (...) in internal clock speed predict chronostasis effects proportional to stimulus duration. No evidence for proportionality was found. Two further experiments assessed the appropriateness of the control conditions employed. Results indicated that the chronostasis effect is constant across a wide range of stimulus durations and does not reflect the pattern of visual stimulation experienced during a saccade, suggesting that arousal is not critical. Instead, alternative processes, such as one affecting the onset of timing are implicated. Further research is required to select between these alternatives. (shrink)

Time is a fundamental dimension of consciousness. Many studies of the “sense of agency” have investigated whether we attribute actions to ourselves based on a conscious experience of intention occurring prior to action, or based on a reconstruction after the action itself has occurred. Here, we ask the same question about a lower level aspect of action experience, namely awareness of the detailed spatial form of a simple movement. Subjects reached for a target, which unpredictably jumped to the side on (...) some trials. Participants expressed their expectancy of a target shift during the upcoming movement, pointed at the target as quickly and accurately as possible before returning to the start posiment to the target shift if required and reproduced the spatial path of the movement they had just made, as accurately as possible, to give an indication of their awareness of the pointing movement. We analysed the spatial disparity between the initial and the reproduced movements on those with a target shift. A negative disparity value, or undershoot, suggests that motor awareness merely reflects a sluggish record of coordinated motor performance, while a positive value, or overshoot, suggests that participants’ intention to point to the shifting target contributes more to their awareness of action than their actual pointing movement. Undershoot and overshoot thus measure the reconstructive and the preconstuctive aspects of action awareness, respectively. We found that trials on which subjects strongly expected a target shift showed greater overshoot and less undershoot than trials with lower expectancy. Conscious expectancy therefore strongly influences the experience of the detailed motor parameters of our actions. Further, a delay inserted either between the expectancy judgement and the pointing movement, or between the pointing movement and the reproduction of the movement, had no effect on visuomotor adjustment but strongly influenced action awareness. Delays during either interval boosted undershoots, suggesting increased reliance on a time-limited sensory memory for action. The experience of action is thus strongly influenced by prior thoughts and expectations, but only over a short time period. Thus, awareness of our actions is a dynamic and relatively flexible mixture of what we intend to do, and what our motor system actually does. (shrink)

Time is a fundamental dimension of consciousness. Many studies of the “sense of agency” have investigated whether we attribute actions to ourselves based on a conscious experience of intention occurring prior to action, or based on a reconstruction after the action itself has occurred. Here, we ask the same question about a lower level aspect of action experience, namely awareness of the detailed spatial form of a simple movement. Subjects reached for a target, which unpredictably jumped to the side on (...) some trials. Participants (1) expressed their expectancy of a target shift during the upcoming movement, (2) pointed at the target as quickly and accurately as possible before returning to the start posiment to the target shift if required and (3) reproduced the spatial path of the movement they had just made, as accurately as possible, to give an indication of their awareness of the pointing movement. We analysed the spatial disparity between the initial and the reproduced movements on those with a target shift. A negative disparity value, or undershoot, suggests that motor awareness merely reflects a sluggish record of coordinated motor performance, while a positive value, or overshoot, suggests that participants’ intention to point to the shifting target contributes more to their awareness of action than their actual pointing movement. Undershoot and overshoot thus measure the reconstructive (motoric) and the preconstuctive (intentional) aspects of action awareness, respectively. We found that trials on which subjects strongly expected a target shift showed greater overshoot and less undershoot than trials with lower expectancy. Conscious expectancy therefore strongly influences the experience of the detailed motor parameters of our actions. Further, a delay inserted either between the expectancy judgement and the pointing movement, or between the pointing movement and the reproduction of the movement, had no effect on visuomotor adjustment but strongly influenced action awareness. Delays during either interval boosted undershoots, suggesting increased reliance on a time-limited sensory memory for action. The experience of action is thus strongly influenced by prior thoughts and expectations, but only over a short time period. Thus, awareness of our actions is a dynamic and relatively flexible mixture of what we intend to do, and what our motor system actually does. (shrink)