Contextual distinctiveness produces long-lasting priming of pop-out

Maljkovic and Nakayama have demonstrated memory influences in singleton search from one trial to the next, an effect they termed priming of pop-out (PoP). This effect was described as resulting from the persistence of an implicit memory trace, the influence of which could be observed for around 5-8 subsequent trials. Thomson and Milliken (2012) recently reported that PoP effects can survive a lag of up to 16 trials for "rare" trials that were composed of distinct target and distracter colors relative to intervening "common" trials. The present experiments tested the idea that long-term PoP effects can depend on the retrieval of distinct contextual cues. Across the experiments reported here, rare trials differed from common trials in spatial location (Experiments 1A and 2A), stimulus configuration (Experiments 1B and 2B), target and distracter colors (Experiments 2A and 2B), or response-selection task (Experiment 3). PoP effects that survived 15 intervening trials were observed with rare search stimuli that were composed of distinct target and distracter colors or required a distinct selection task. Distinct stimulus location and distinct stimulus configuration failed to produce a measurable effect on PoP for rare trials, either on their own or in conjunction with other distinct features. These results are interpreted as evidence that episodic memory retrieval processes can produce relatively long-term PoP effects.