Facilitatory and inhibitory effects of masked prime stimuli on motor activation and behavioural performance.

Three experiments investigated the impact of information provided by masked stimuli on motor activation. Masked primes were presented prior to target stimuli and these primes were identical to the target on compatible trials, identical to the target mapped to the opposite response on incompatible trials and task-irrelevant on neutral trials. A previous study [Eimer, M., & Schlaghecken, F. (1998). Effects of masked stimuli on motor activation: Behavioural and electrophysiological evidence. Journal of Experimental Psychology: Human Perception and Performance, 24, 1737-1747] found performance costs for compatible trials and benefits for incompatible trials. Experiment 1 showed that these effects are not due to 'perceptual repetition blindness'. Experiments 2 and 3 obtained evidence for an initial response facilitation triggered by the primes that was followed by inhibition. With short intervals between prime presentation and response execution, performance benefits were found for compatible trials and these turned into costs at longer intervals. It is argued that an early response facilitation mediated by direct perceptuo-motor links is subsequently inhibited by a central mechanism operating to prevent behaviour from being controlled by irrelevant information.