Why does what you’re moving affect how fast you search?

Visual search is faster when moving an aperture over a search display than when moving a search display beneath an aperture. Is this difference in search times because of the way in which spatial information is represented? Spatial information can be represented egocentrically (items relative to oneself) or allocentrically (items relative to each other). Allocentric spatial information does not depend on whether one moves the aperture or the display. Egocentric information does. When moving the aperture, each item in the display is sampled at a different egocentric position, which might help keep track of where one has already searched. When moving the search display, allocentric information must guide search because all items are sampled at the same egocentric position. To find out whether search is faster when moving an aperture because having egocentric information makes it easier to keep track of where the target might be, we investigated the effect of improving the allocentric information. If participants primarily rely on egocentric information when moving the aperture and allocentric information when moving the search display, providing additional allocentric information should only improve performance when moving the search display. Participants were asked to search for a target amongst distractors as quickly as possible. In two blocks of trials the computer mouse was linked to the aperture. In another two blocks of trials, it was linked to the search display. In one of each pair of blocks the extent of the search display was constantly visible, providing additional allocentric information. In the other it was not. When moving the aperture, providing additional allocentric information did not affect search times. When moving the search display, search was faster with the additional allocentric information. Thus, the use of egocentric information makes search faster when moving an aperture than when moving a display beneath an aperture.