Oscillations in motor priming: positive rebound follows the inhibitory phase in the masked prime paradigm

Masked stimuli can cause partial motor activation and prime responses to subsequent stimuli. Under certain conditions, a biphasic pattern appears, such that positive priming precedes a negative phase, which has been interpreted as evidence of an inhibitory mechanism that suppresses the motor activity caused by the prime. In this article, the authors report evidence for a further reversal in priming: In two experiments, the authors found that the negative compatibility effect was followed by a small but repeatable positive priming effect at an interval of approximately 500 ms between prime and target. Thus, masked primes appear to produce a triphasic pattern of priming, which is consistent with the notion that oscillation between facilitation and inhibition may be a fundamental property of the competitive interactions between response alternatives in the motor system.