Instructing item-specific switch probability : Expectations modulate stimulus-action priming

Kurzfassung/Abstract

Both active response execution and passive listening to verbal codes (a form of instruction) in single prime trials lead to item-specifc repetition priming efects when stimuli re-occur in single probe trials. This holds for task-specifc classifcaction (stimulus–classifcation, SC priming, e.g., apple–small) and action (stimulus–action, SA priming, e.g., apple–right key press). To address the infuence of expectation on item-specifc SC and SA associations, we tested if item-specifc SC and SA priming efects were modulated by the instructed probability of re-encountering individual SC or SA mappings (25% vs. 75% instructed switch probability). Importantly, the experienced item-specifc switch probability was always 50%. In Experiment 1 (N=78), item-specifc SA/SC switch expectations afected SA, but not SC priming efects exclusively following active response execution. Experiment 2 (N=40) was designed to emphasize SA priming by only including item-specifc SC repetitions. This yielded stronger SA priming for 25% vs. 75% expected switch probability, both following response execuction as in Experiment 1 and also following verbally coded SA associations. Together, these results suggest that SA priming effects, that is, the encoding and retrieval of SA associations, is modulated by item-specifc switch expectation. Importantly, this expectation efect cannot be explained by item-specifc associative learning mechanisms, as stimuli were primed and probed only once and participants experienced item-specifc repetitions/switches equally often across stimuli independent of instructed switch probabilities. This corroborates and extends previous results by showing that SA priming efects are modulated by expectation not only based on experienced item-specifc switch probabilities, but also on mere instruction.