Abstract
We often search for a target object made of more than one single feature, and this supposedly requires storage of solid and bound representations of multiple features in memory. How long does it take then to form such a cohesive representation of a search target? In this study, we attempted to estimate the time necessary for forming a reliable representation of a multi-feature target by varying the delay of search array onset after designating the target feature(s). In both simple- and conjunction-feature search blocks, the target feature(s) was designated by sequentially displaying two items, and each item can possess either of two target features (e.g., color or orientation). Following after the blockwise designation of the target feature(s), the search array was displayed with randomly-chosen one of three different onset delays of 50, 500 and 1500ms. In the simple-feature search condition, the search array was made only of a target feature informed in the block, supposedly preventing the use of the other irrelevant target feature. Whereas in the conjunction-feature search condition, the search array was made of both features according to the way a conventional conjunction search array is constructed. The results showed that search RTs from the simple-feature condition were constant regardless of the onset delays of search array, but were relatively slower than the RTs from the conjunction-search condition. Such advantage in the conjunction-search condition was observed only if the onset delay of the search array was longer than 500ms. The results indicate that forming a durable target template in visual search requires a bit of time, and further suggest that on a special occasion, searching for a target consisting of multiple features can lead to faster search performance than searching for a target with a single feature if enough time to form a solid target representation is provided.
Meeting abstract presented at VSS 2013