Abstract
Visual search performance is strongly affected by what happened one moment ago: what we attended to, what we ignored and how we responded. Such effects have been studied by means of inter-trial effects in visual search, such as the priming of pop-out effect (PoP, Maljkovic & Nakayama, 1994), which shows that performance on singleton search is faster when the target and distractors features repeat on two consecutive trials than when they switch. The current literature is polarized with regard to whether PoP affects early, perceptual processing or later, response-related processes. We recently suggested a dual-stage model (Lamy, Yashar, & Ruderman, 2010), which includes both a perceptual and a response-based component, and can accommodate findings that had so far been viewed as contradictory. We present new evidence that help us clarify how the perceptual and response-based mechanisms that underlie PoP interact during visual search and identify the boundary conditions of each mechanism. In the present series of experiments, we show that in singleton search (1) perceptual PoP effects are observed only when the task requires focused attention, (2) response-based processes affect performance only when target selection is difficult, namely, when target-distractor discriminability is low, (3) the characteristics of the whole display rather than of the target alone are compared across views and trigger retrieval of the associated response, and (4) the response-based component of PoP speeds motor response preparation and/or execution rather than discrimination of the response feature. We discuss what PoP can teach us about visual search, in light of the model.