Examining eye movements in visual search through clusters of objects in a circular array

Abstract

Participants were asked to search for a complete O in an array consisting of eight clusters of four Landolt Cs (i.e., Os with a gap) arranged in a ring. The size of the gap in the Cs varied from cluster to cluster but was held constant within a cluster. The manual response time data were consistent with a serial self-terminating search. More importantly, eye movement data supported a serial processing model as (1) clusters were fixated serially (either clockwise or counterclockwise) on most trials and (2) 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. 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 our previous findings in which search was through a linear sequence of clusters, and indicate that a serial search pattern through clusters of these kinds of objects is not confined to reading-like linear arrays.

Keywords:

• Clusters
• Eye movements
• Visual search

This research was supported by an NIH R01 Grant [grant number HD26765] to the second author and Keith Rayner and an NIH R01 Grant [grant number HD053639] awarded to the third author.

Portions of this work were presented at the 2011 annual meeting of the Vision Science Society in Napels, FL.

This research was supported by an NIH R01 Grant [grant number HD26765] to the second author and Keith Rayner and an NIH R01 Grant [grant number HD053639] awarded to the third author.

Portions of this work were presented at the 2011 annual meeting of the Vision Science Society in Napels, FL.

Notes

¹ Although the diagonal clusters were slightly closer to the starting point, only 2 of the 10 participants showed a preference for selecting those clusters first.

² Because of an equipment change, a screen resolution of 800 × 600 was used in the current experiment compared to 1600 × 1200 in Williams and Pollatsek (2007). To compensate, the current experiment used 1-, 2-, 3- and 4-pixel gaps rather than 2-, 4-, 6- and 8-pixel gaps. However, the visual angles of the gaps, and stimuli in general, were approximately the same as those in Williams and Pollatsek.