Abstract
The current study investigated whether the precision of visual working memory could be changed by the number of subsets, with the number of items unchanged. Specifically, we always presented five differently oriented bars but varied the number of subsets. We assumed that similarly oriented bars would be organized as one subset while dissimilar bars would be treated as other subsets. Within a subset the orientation difference of all bars was 5°, and across subsets, the smallest orientation difference between two bars was 45°. Thus, within a subset all bars had similar orientations, but across subsets bars had dissimilar orientations. If subsets are used as units of visual working memory rather than individual bars, the precision of represented bars should decrease as the number of subsets increases. In Experiment 1 and 2, five differently oriented bars were presented for 200ms. After 900ms, a bar whose orientation could be adjusted by a mouse was presented in the center of the screen with a circle indicating one specific location of the encoded bars. Participants were asked to recall the orientation of the item indicated by the circle. In Experiment 1, there were two conditions with one subset and two subsets, and in Experiment 2 there were also two conditions with two subsets and three subsets. We compared memory precision between the two conditions in each experiment, with the following steps being taken: (a) the five bars were sorted by their orientations in each subset condition; and (b) the orientation precision of corresponding bars was compared between the subset conditions. We found that the precision of reported orientation decreased as the number of subsets increased. These results suggest that items held in visual working memory are organized into subsets depending on orientation similarity and the subsets are represented as units of visual working memory.
Meeting abstract presented at VSS 2017