Psychological Refractoriness of Two Serial Motor Responses

The memory drum and single channel concepts of refractoriness were examined, using a forward lunge with a concurrent right-arm swing as the primary response and a right-thumb key release for the second response. Interstimulus intervals (ISIs) ranged from .10 to .50 sec. in 10-sec. steps; they were presented in a random order. While movement refractoriness decreased with ISI, no residual capacity was evident in examining the single channel model making channel occupation time equal to RT1. The possibility that CRT1 (central refractory time, 6) was of variable duration was also noted. The fact that the correlations between RT1 and RT2 implied little generality of individual differences emphasized the need for further research if single channel models are to achieve closer approximations to data arising from the study of the ability to execute consecutive paired responses.