Reduced attention and the performance of "automated" movements.
3 repetitive movements were studied. These were a blind movement between 2 stops, a visually guided movement to a line and a blind movement which had to be terminated at a previously learned position. Previous work had shown that the first of the three caused no interference with RT to a secondary signal presented during the movement, while the other two did interfere. Ss either performed the movement task alone, together with an attention demanding key positioning task, or under an instruction to think about something else. The variability of movement and pause time was used to score the movement tasks. When the movement was performed alone, variability was least for the blind movement between stops and most for the blind movement with a remembered target All tasks showed increased variability when performed with the subsidiary key task. The instruction to think about something else generally increased variability but not significantly. The task component showing the least influence of the secondary task was the variability of movement distance in the blind task without stops.
a Department of Psychology , University of Oregon.
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Posner