How do we know what we are doing ? Time , intention and awareness of action q

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. 2007 Elsevier Inc. All rights reserved. www.elsevier. com/locate/concog 1053-8100/$ see front matter ! 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.concog. 2007.03. 007 q Jean-Christophe Sarrazin is a Marie Curie Postdoctoral Fellow at the Cognitive Science Research Unit (ULB, Belgium), Axel Cleeremans is a Research Director with the National Fund for Scientific Research (FNRS, Belgium), and Patrick Haggard is a Professor at the Institute of Cognitive Neuroscience (UCL, England). This work was supported by a grant from the European Commission (Grant MEIF-CT-2005-515499). We thank two anonymous referees for their comments on a previous version of this article, as well as Thelma Coyle and Frank Buloup for their assistance in conducting the experiment. * Corresponding author. Fax: +32 4 91 17 22 54. E-mail addresses: jcsarraz@ulb.ac. be (J.-C. Sarrazin), axcleer@ulb.ac. be (A. Cleeremans), p.haggard@ucl.ac. uk (P. Haggard). Available online at www.sciencedirect. com Consciousness and Cognition 17 (2008) 602–615 Consciousness and Cognition