Abstract
The purpose of the current research was to examine the effects of practice on motor preparation. Participants performed four days of practice in a simple RT paradigm. Three different unimanual movements were chosen that differed in movement amplitude and number of elements and included: short (20°), long (40°), and two-step (stop at 20°continue to 40°) movements. On day 1 and 4, a startling stimulus was used to probe the preparation process by triggering the prepared movement. We found evidence for a sequence length effect for control trials on day 1 whereby the two-step movement had an increased reaction time; however with practice this effect was minimized. During startle trials, all movements were triggered at a short latency with similar consistency to control trials. Collectively these results suggested that participants fully prepared all movements in advance, including the sequenced movement. We hypothesized that complexity may relate more to the neural commands needed to produce the movement, rather than a sequencing requirement. These results are discussed in terms of current theories for sequential movement preparation.Acknowledgments: Acknowledgements for this study go to a Natural Sciences and Engineering Research Council of Canada grant awarded to Ian M. Franks.