Dissociating object- and response-based components of negative priming through effects of practice

The negative priming (NP) effect is the slowing of responses to an imperative stimulus (probe) that has recently been ignored (prime). Prevailing accounts of the phenomenon attribute it to a variety of causes, all centered on a representation of the stimulus event itself. However, we argue that the most commonly used NP paradigms confound stimulus- and response-based factors. In two experiments, we demonstrate the importance of response factors in producing NP and show clear empirical dissociations between object- and response-centered NP when studying their time courses over extended practice. When distractors compete for a response (response-based), the NP effect is both more robust and more resistant to the effects of practice. On the other hand, when prime distractors do not compete for response (object-based), they yield weaker NP effects that disappear with practice. We conclude that the NP effects shown in the most common procedures are produced by a combination of distinct factors that tend to act in the same direction.