Examining mechanistic explanations for Ideomotor effects

Ideomotor (IM) theory provides a popular mechanistic account for understanding how goal-directed action can be learned and instigated. That is, when associations between actions and outcomes have been established in memory, the perception or thought of the outcome could automatically activate the associated action. Whereas a sizable literature provides evidence in line with this account, it does not successfully exclude alternative explanations in terms of propositions based on causal inferences. In the present paper, we present an online IM paradigm, in which learning and testing occurs on the same trials. In line with recent findings, we demonstrate that IM effects can emerge within a couple of trials, but also that people can update learned action–outcome associations immediately when a new mapping of outcomes on actions is introduced, without any switch costs. Together, this suggests that IM effects may be driven by propositions about causal relations, rather than bidirectional associations stored in memory.