The Effect of Motor and Sensory Set on Reaction Time and Muscle Electircal Activity

Abstract

The superiority of motor set reaction time over sensory set reaction time has been accepted since the 1880s. Recently, however, there has been work favoring the sensory set. This study attempted to reconcile the varied findings. Woodworth had suggested that set and stimulus intensity interact. To test that presumed interaction and related ideas, the study proposed to determine not only the effect of motor set and sensory set on reaction time (RT) and muscle electrical activity (MEA), but also, the relationship between motor set and sensory set RT and motor set and sensory set MEA. Twenty-four subjects were tested in sessions that included the placement of electrodes on the motor end point of the extensor digitorum muscle, set instructions, practice, and data collection. Data collection consisted of recording of RT and MEA for 96 trials, 12 recordings at each of four levels of auditory stimulus intensity for each of the two sets. An ANOVA for repeated measures produced a significant interaction between set and intensity for RT; thus the Woodworth prediction was upheld. The results seem best explained in terms of signal detection theory and the attention demands of movement.