Abstract
Objects tend to be clustered in the environment. This clustering could affect both search processes and the eye movements used to execute a search. In order to examine this possibility, participants in the current study were asked to search for a complete O in an array consisting of eight clusters of four Landolt Cs arranged in a ring. The similarity of the distractors to the target was manipulated systematically by varying the size of the gap in the Cs, but the gap size for all of the Cs in a cluster was the same. Consistent with many search studies, the response time data were consistent with a serial self-terminating process. More importantly, eye movement data supported the serial processing model because clusters were fixated serially (either clockwise or counterclockwise) on most trials and (b) fixation times on a cluster reflected processing time on that cluster and were unaffected by the gap size of either the prior or succeeding cluster. In other words, processing difficulty of a cluster had no effect on later fixations, nor did the processing difficulty of a cluster affect fixations before that cluster was fixated. Furthermore, the pattern of fixation times on a cluster was similar to the pattern of response times in a secondary task where a single cluster was presented at fixation. These data extend the findings of Williams and Pollatsek (2007) in which search was through a linear sequence of clusters, and indicate that a serial search pattern is not confined to reading-like arrays.
NIH R01 Grant HD26765 to Keith Rayner and Alexander Pollatsek and NIH R01 Grant HD053639 to Erik Reichle.