The influence of catch trial frequency on simple reaction time

The major purpose of the present investigation was to examine the combined influence of variations in foreperiod length (1.0, 5.0 sec) and catch trial frequency (0.0, 0.1, 0.2) on simple reaction time (RT) magnitude when verbal mediation was permitted and when it was not. A significant foreperiod length, catch trial frequency, mediation type interaction was obtained supporting the notion that all three factors influence a common process (i.e. Sternberg 1969), here called ‘preparation’. More specifically, for the non-mediation group, foreperiod length and catch trial frequency had both additive (0.0 vs 0.1) and interactive (0.1 vs 0.2) effects on mean simple RT while only catch trial frequency significantly altered simple RT for the mediating group. In all instances, mean simple RT increased significantly when some catch trials were employed as opposed to when none were used, a finding which was interpreted as reflecting an induced preparation decrement upon the introduction of catch trials.