Abstract
Changes to visual scans were examined during repeated visual search across two experiments. There were significant scan pattern adjustments when relatively unique stimuli were searched, and greater adjustments when stimuli were searched repeatedly. Changes occurred despite participants being unaware that some stimuli repeated. Differences between scan patterns could result from either chaotic or systematic changes in behavior. We hypothesized that changes in scan patterns were systematic, and argue that the changes reflect adaptations to the task environment.
Skill acquisition is the process of adapting behavior with experience. Adaptation can occur at relatively low and high levels of behavior (Gray & Boehm-Davis, 2000). Similar to acquiring a skill, visual scans could be adapted to a set of stimuli with experience. To conclude that scans were adapted to stimuli, data had to meet three criteria. First, the number of fixations to find the target must be reduced with experience (Criterion-1). Second, the similarity of scan patterns had to increase with experience (Criterion-2). Third, scan patterns from repeated stimuli must become similar at a faster rate than patterns from relatively unique stimuli (Criterion-3).
In experiment-1, participants performed 720 trials in the repeating visual search paradigm (RVSP; 360 mostly unique trials +12 trials repeated 30 times, each). In experiment-2, participants performed the RVSP with or without a simultaneous auditory letter classification task. Criterion-1 and Criterion-2 were met in the first experiment, and all three criteria were met in the second experiment. Moreover, scan pattern similarities were reduced when performing a secondary auditory task. The results indicate that scan patterns were adapted to regularity within the search stimuli
References Gray, W. D., & Boehm-Davis, D. A. (2000). Milliseconds matter: An introduction to microstrategies and to their use in describing and predicting interactive behavior. Journal of Experimental Psychology-Applied, 6(4), 322-335.
This research was supported, in part, by a grant from the Air Force Office of Scientific Research AFOSR #FA9550-06-1-0074, to Wayne D. Gray.