Response programming,response production,and fractionated reaction time

Summary A feature common to many studies investigating the relationship between reaction time (RT) and motor task demands is that, prior to responding, subjects have been able to preview the parameters of the movement they are required to make. This introduces the possibility of preprogramming the movement before entering the RT period, thus making it more difficult to detect a consistent relationship between RT and motor task demands. A no-preview condition (movement parameters concealed prior to the subject responding) was used in the present study to avoid this confusion. Reaction time was fractionated using surface EMG recording, and premotor RT (central component) was found to vary with motor task demands in a fashion supporting a study by Sheridan (1981). Movement velocity was implicated as a factor influencing programming difficulty, with low velocity movements appearing to present the greatest problem. A strong negative correlation was observed between premotor RT and average movement velocity. A delay condition was incorporated into the present study to consider the retention in memory of the programmed information. Briefly, the pattern of results for the delay condition fell between the no-preview and preview conditions. The implications of these findings are discussed.