Mask stimulus triggers inhibition in subliminal visuomotor priming.

To explain the reversal in reaction time benefits between positive and negative subliminal visuomotor priming, most researchers propose the existence of inhibitory processes acting on the initial motor activation by the prime. However they diverge regarding whether this inhibition is self-generated within the motor system or stimulus-triggered by the appearance of novel stimuli following the prime (usually the mask). To disentangle these two hypotheses, in our study the mask object could appear before prime presentation and move toward the prime location so that it eventually masked it. In this condition, in which no new stimulus appeared after the prime, a positive compatibility effect was found. Conversely, in two other experiments in which the mask was not displayed before prime presentation, we retrieved the classical negative compatibility effect. Thus the appearance of the mask after the prime plays an important role in triggering inhibition of motor activation generated by subliminal primes.