Abstract
In visual search tasks, memory of the target features and positions in the past three to ten trials affects the present search performance. This is called “priming of the pop-out” or “repetition effect in visual search”. Using the concurrent tasks of visual search and visuo-spatial n-back tasks, we reported that the capacities and the stored representations between visuo-spatial working memory and the memory system contributing to the effect was not the same (Yoshida, et al., VSS2002). This time we reports that the same tendency is obtained when observers can not use verbal strategies and when they are required binding of the target color and position in their visuo-spatial working memory.
We used concurrent triple tasks (visual search, visuo-spatial n-back tasks, and articulatory suppression). Observers were required to search for an odd-colored target in a display and to quickly respond to the subtle shape of it, while maintaining the pre-instructed characteristic (color, position, and both) of the targets in the past n trials to judge whether the characteristic of the current target was the same as the target that had been presented n trials back. They also repeated a word out loud every 1 sec.
Observers successfully performed the triple task even if their visuo-spatial working memory was near its upper limit (around three). In all of the n-back tasks, reaction times were affected from a larger number of past trials (at most ten for the position). Moreover, the target characteristics observers did not maintain in their visuo-spatial working memory also affected current search performance. These results suggest that visual system accumulate the memory of the past attentive events even if the observer's visuo-spatial working memory is full.