Abstract
Attention toward extrapersonal world has been intensively investigated. However, attention toward internal representations held in visual working memory has remained relatively unexplored. Recently, it has become clear that it is also possible to orient selective spatial attention to internal representations held in working memory (Griffin et al., 2003). Since selection by visual attention can be made not only on the basis of locations, but also on the basis of simple features such as color and shape, we employed feature-based retro-cues to test whether it is possible to use features to direct attention in visual working memory. Sixteen subjects took part in the current experiment and each of them completed all the three kinds of tasks, the color-cue task, the shape-cue task and the spatial-cue task. In each task, subjects were either cued to select an stimulus before the memory array was presented (pre-cue), cued to select an item in visual working memory after the memory array was presented (retro-cue), or given no cueing information (neutral cue). The memory array consisted of four different colored shapes. At the end of the trial, a test stimulus was presented and subjects responded according to whether it matched the item presented at the same location in the memory array. Behavioral performance was modulated by the presence of a feature-based cue in both pre-cue and retro-cue trials, indicating that it is also possible to use features to direct attention in visual working memory. Moreover, we noted a difference in the pattern of behavioral benefits between feature-based selection and space-based selection. Significantly larger cueing effects for pre-cues compared to retro-cues were observed in the color-cue and shape-cue task, while no difference between pre-cues and retro-cues was found in the spatial-cue task. These results might reflect different underlying processes between feature-based selection and spatial selection.