Visual search is a widely studied paradigm involving laboratory versions of the common real-world problem of finding an item of current interest among a cluttered visual scene containing many items (for reviews, see Kristjánsson, 2006; Kristjánsson & Campana, 2010; Müller & Krum- menacher, 2006; Wolfe, 1998; Wolfe & Horowitz, 2004). Early accounts of visual search (e.g., Julesz, 1984; Neis- ser, 1967; Treisman & Gelade, 1980) mainly emphasized the role of bottom-up feature contrasts in determining how well a target stands out from surrounding nontargets. Subsequent research has shown that the effects of such bottom-up saliency can be modulated by other factors, such as the behavioral importance of the stimuli (Ivry & Cohen, 1990; Müller, Heller, & Ziegler, 1995; D. Wang, Kristjánsson, & Nakayama, 2005; Q. Wang, Cavanagh, & Green, 1994; Wolfe, Cave, & Franzel, 1989, although such top-down modulations seemingly have their limits: see Van der Stigchel et al., 2009), or by what has occurred on previous trials (e.g., Becker, 2008; Geyer, Müller, & Krummenacher, 2006; Kristjánsson & Driver, 2008; Lamy, Antebi, Aviani, & Carmel, 2008; Maljkovic & Nakayama, 2000; Olivers & Meeter, 2006; Sigurdardottir, Kristjáns- son, & Driver, 2008; see Kristjánsson, 2008, for a review). Observers typically perform better in search when the same target is repeated on successive trials, as compared with when the target changes, even for so-called pop-out 1229 © 2010 The Psychonomic Society, Inc. BRIEF REPORTS Fortune and reversals of fortune in visual search: Reward contingencies for pop-out targets affect search efficiency and target repetition effects ÁRNI KRISTJÁNSSON University of Iceland, Reykjavik, Iceland and University College London, London, England ÓLAFÍA SIGURJÓNSDÓTTIR University of Iceland, Reykjavik, Iceland AND JON DRIVER University College London, London, England Rewards have long been known to modulate overt behavior. But their possible impact on attentional and per- ceptual processes is less well documented. Here, we study whether the (changeable) reward level associated with two different pop-out targets might affect visual search and trial-to-trial target repetition effects (see Maljkovic & Nakayama, 1994). Observers searched for a target diamond shape with a singleton color among distractor diamond shapes of another color (e.g., green among red or vice versa) and then judged whether the target had a notch at its top or bottom. Correct judgments led to reward, with symbolic feedback indicating this immediately; actual rewards accumulated for receipt at study end. One particular target color led to a higher (10:1) reward for 75% of its correct judgments, whereas the other singleton target color (counterbalanced over participants) yielded the higher reward on only 25% of the trials. We measured search performance in terms of inverse ef- ficiency (response time/proportion correct). The reward schedules not only led to better performance overall for the more rewarding target color, but also increased trial-to-trial priming for successively repeated targets in that color. The actual level of reward received on the preceding trial affected this, as did (orthogonally) the likely level. When reward schedules were reversed within blocks, without explicit instruction, corresponding reversal of the impact on search performance emerged within around 6 trials, asymptoting at around 15 trials, apparently without the observers’ explicit knowledge of the contingency. These results establish that pop-out search and target repetition effects can be influenced by target reward levels, with search performance and repetition effects dynamically tracking changes in reward contingency. Attention, Perception, & Psychophysics 2010, 72 (5), 1229-1236 doi:10.3758/APP.72.5.1229 Á. Kristjánsson, ak@hi.is