Eimer, M., Schub, A., & Schlaghecken, F. (2002). Locus of inhibition in the masked priming of response alternatives. Journal of Motor Behaviour, 34, 3-10.
Masked primes presented immediately before targets in a choice reaction task give rise to behavioral costs when primes and targets are mapped to the same response, and result in benefits when they are mapped to opposite responses. This negative compatibility effect is assumed to reflect inhibitory processes in the control of perceptuo-motor links. It was investigated whether this inhibition operates at the level of abstract central codes or at effector-specific motor stages. In two experiments, left or right hand or foot responses were required to targets preceded by masked arrow primes that were mapped to the same response side as the targets in compatible trials, to the opposite response side in incompatible trials, and were irrelevant in neutral trials. Experiment 1 found that when the masked primes determined both response side and modality, there was no transfer of negative compatibility effects across response modalities. This is inconsistent with a central abstract locus of inhibition, and suggests that inhibition operates at effector-specific motor stages. In Experiment 2, where primes only conveyed response side information, but left response modality uncertain, negative compatibility effects were elicited both for hand and foot responses, suggesting that partially informative masked primes can trigger a parallel activation and subsequent inhibition of response processes within separate effector systems.