Cross-trial priming of element positions in visual pop-out search is dependent on stimulus arrangement

Two experiments examined cross-trial positional priming (V. Maljkovic & K. Nakayama, 1994, 1996, 2000) in visual pop-out search. Experiment 1 used regularly arranged target and distractor displays, as in previous studies. Reaction times were expedited when the target appeared at a previous target location (facilitation relative to neutral baseline) and slowed when the target appeared at a previous distractor location (inhibition). In contrast to facilitation, inhibition emerged only after extended practice. Experiment 2 revealed reduced facilitatory and no inhibitory priming when the elements' spatial arrangement was made irregular, indicating that positional--in particular, inhibitory--priming critically depends on the configuration of the display elements across sequences of trials. These results are discussed with respect to the role of the context for cross-trial priming in visual pop-out search.