title: Effects of number of alternatives on the psychological refractoriness of an extended movement .
abstract: The single-channel prediction that delays in RT2 should be proportional to RT1 was examined by varying the number of alternatives (one, two, or three) in the primary response which was an extended arm swing at maximal speed. The second response was a thumb key release. Foreperiods were 2, 3, or 4 sec., and interstimulus intervals (ISIs) ranged from .10:50 sec. in .10-sec. steps. General support for the single-channel model was found in that RT2 paralleled changes in RT1. However, RT2 was greater than predicted when the second signal (S2) occurred during the execution of the primary response. In addition, while delays in RT2 as a function of ISI - RT1 showed corresponding differences between choice conditions, most values were greater than predicted. The deviations from the single-channel model appeared to be explained best in terms of a decrease in readiness to respond to the second signal as ISI lengthened.
authors: a School of Physical Education , University of Otago, New Zealand.
authors: L R
authors: LR
authors: Williams