Abstract
Attention is the ability to ignore irrelevant stimuli and focus only on what is currently of interest. Although it is typically studied in the context of filtering out information we are currently perceiving, attention can also be directed internally towards memory. Previous work has shown that internally directed attention acts in much the same way as externally directed attention, though there are some differences, likely due to the difference between perceptual and memory representations. Here, I demonstrate another one of these differences. Participants remembered a display consisting of three or five colored shapes. After the participant indicated that they had memorized the display, a mask was presented for 1000 ms, followed by a 1500 ms blank screen. Finally, the participant was asked to find a target and indicate whether it was on the left or right side of the display. The target was identified by either its color, shape or by its color and shape. As expected, participants were fastest at finding the target when it was identified by its color. However, participants were no faster to find the target when identified by its shape than when identified by a color-shape conjunction. Experiment 2 and 3 confirmed that this effect is not due to the specific features chosen: color is again dominant for color-orientation pairings, while shape is dominant for shape-orientation pairings. Experiment 4 demonstrates that this primacy of one feature is under voluntary control, as shape is still dominant over orientation when the oriented shapes have irrelevant colors. Together the results suggest that objects in visual working memory are indexed based on a single dominant feature, while accessing other features requires first accessing the dominant one.