Abstract
Attending and processing stimuli on one trial can facilitate processing of stimuli with the same features on the next trial, a phenomenon termed intertrial priming. Few accounts that explain priming mechanistically have been proposed yet, but one theory proposes that episodic retrieval of past trials has a crucial role. Using an established model of episodic LTM, we were indeed able to reproduce various findings from the priming literature. However, the general principles of learning embedded in the model yielded a counterintuitive prediction: a block with a surplus of trials in which the target has, for example, a certain color (a bias block), will result in long-term priming, speeding search for such targets for the remainder of the experiment. Testing this prediction, we found a remarkable dissociation between singleton- and conjunction search: No long-term learning effects were found for singleton search, but for conjunction search we found that bias blocks affected search in later unbiased blocks, without obvious forgetting. Further experiments clearly illustrated this effect could be ascribed to long-term memory mechanisms, as long-term priming persisted after an intervening week. Furthermore, this long-term priming effect did not seem to result from an explicit strategy recruited by the participants and occurred on top of short-term intertrial priming. Based on these findings, and findings from neurophysiology, we propose to dissociate priming effects found in singleton and conjunction search, and illustrate how priming may fractionate in short- and long-term effects through separate mechanisms.
Meeting abstract presented at VSS 2014