Effects of Changing Compatibility Relationships on Reaction Time to the First Stimulus in a Double-Stimulation Task

Abstract

This study investigated the effects of manipulating the response requirement to the second stimulus (S₂) on reaction time (RT) to the first stimulus (S₁) in a double-stimulation choice RT task. Forty subjects responded to the 100 msec presentation of a left or right light by pressing the key on the same or opposite side as the light. Treatment conditions included a single-stimulation control (no S₂ presented), and two double-stimulation conditions each requiring two responses (R₁ and R₂) in close succession. In one of these latter conditions, the rule governing R₂ was the same as that governing R₁ while, in the other, the rule governing R₂ changed. Results showed the typical double-stimulation effect; i.e., increased latency of R₁ when it was followed by S₂ – R₂. More importantly, R₁ latency was increased further when the rules governing R₁ and R₂ were different. Results are discussed in terms of divided preparation capacity as well as other theories of the psychological refractory period.