In the response priming paradigm, a small briefly presented visual stimulus (i.e., prime) is followed by a larger visible stimulus (i.e., mask) that renders the prime invisible and specifies the target location. According to the rapid-chase theory, the initial portion of the movement is dictated by the prime (initiation criterion) while the later portion is dictated by the mask (takeover criterion) and the prime is initially processed independently from the mask (independence criterion). The purpose of the first experiment was to determine if the processing of the prime and mask fit the predictions of the rapid-chase theory when the prime and mask are presented during an ongoing movement. The second experiment was designed to examine the impact of the prime when it is presented at various times throughout the execution of the movement. Participants initiated rapid pointing movements to a center target. On 1/3 of the trials, participants had to correct their movements to the left (or right) target in response to a left-pointing (or right-pointing) mask arrow, which was preceded by a neutral, left-, or right-pointing prime arrow. In Experiment 1, the prime was presented at movement onset and the mask randomly appeared 33, 50, or 67 ms after prime onset. In Experiment 2, the prime followed movement onset with a delay of 17, 33, or 50 ms and the mask was presented 50 ms after prime onset. In both experiments, participants first modified their movements in the direction indicated by the prime before completing their movements to the correct target in the majority of trials; thus, supporting the initiation and takeover criteria. However, the spatial priming effects did not follow the time course predicted by the independence criterion. Overall, the rapid-chase theory does not seem to apply to movement execution, but the prime is still able to influence the movement despite being presented later in the pointing trajectory.

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