Taking stock: The role of environmental appraisal in the strategic use of attentional control.

There are many strategies we can use to control attention when approaching a visual search task, but some are more effective than others. How do we choose the most optimal strategy? We have proposed that individuals must appraise the stimulus environment, taking in relevant statistical information about task-relevant features. In the present experiments, we examined whether interfering with the appraisal process via a secondary task decreases participants' use of the optimal strategy. We used a modified version of the Adaptive Choice Visual Search paradigm whereby individuals can freely search for either of two targets on every trial. Each search display was preceded by a colored environmental preview, offering participants time to appraise the display and determine which target would be more optimal to search for. On some blocks, participants also completed a secondary task - a central line-length judgment - either before or during this colored preview. We found that participants were significantly less likely to search optimally when the line task occurred during the colored preview than when it occurred beforehand or was absent. Insofar as the secondary task disrupts an individual's ability to engage in appraisal, these results support the need for such an appraisal mechanism in the optimal choice of attentional control settings.