Chang in Cognitive Bag Lunch Weds. April 4 at 12:00

Junha Chang (PBS) will be giving the cognitive brown bag Wednesday April 4 in Tobin 521B, 12:00-1:20).  Title and abstract follow.

Search guidance is sometimes, but not always, adjusted by experience with search discriminability

These experiments show that previous experience with certain types of visual search can influence current search guidance, and explore factors that determine whether these effects of experience arise or not. In a dual-target search task, two subject groups either experienced difficult color discriminability in half of the trials (i.e., hard-discrimination group) or experienced easy discriminability in all trials (i.e., easy-discrimination group). In both experiments, subjects were required to respond whether either of two targets was present or not among distractors. In Experiment 1, the same two colors served as possible target colors for the entire experiment. Fixation rate was high for distractors with colors similar to a target color, and gradually decreased for colors less and less similar to the target color. There was no significant difference between two groups in both eye movement and behavioral results. In Experiment 2, the colors of the two targets were varied from trial to trial in order to increase working memory demand. The hard-discrimination group fixated more distractors with target-dissimilar colors than the easy-discrimination group, suggesting the hard-discrimination group used color information to guide search less than the easy-discrimination group. The results demonstrate that experience of difficult color discriminability discourages observers from guiding attention by color and encourage them to use shape information, but only when working memory load is demanding.

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