Abstract
What we attend to is determined not only by salience and top-down guidance but also by what we have recently attended to. Covert orienting in singleton visual search tasks is faster when a previous search target repeats than when it changes, an effect called priming of pop-out (PoP). While many studies have investigated the characteristics of this form of priming and the mechanisms underlying it, much less is known about the potential usefulness of PoP in determining priorities in attentional selection without a designated target. Our aim was to examine whether priming in visual search plays a role in determining what objects or features we attend to when given a free choice. In a novel procedure we intermixed pop-out trials (one oddball target paired with two identical distractors) with free-choice trials (one object of each kind where neither pops out among distractors) where observers freely chose an object to attend to. Pop-out trials tended to drive subsequent choice, with observers typically choosing the preceding pop-out target. The strength of this effect steadily grew over successive pop-out trials with the same target, such that by six repetitions of the same pop-out target subsequent target choice was determined almost completely. In a second experiment we found that choice trials affected subsequent pop-out response times as strongly as did conventional PoP, indicating full priming build-up from free selection without actual pop-out. Our results support accounts of PoP centered on altered target priority and demonstrate the potent role PoP can play in guiding visual exploration.
Research Fund of the University of Iceland.