Abstract
In most visual search tasks, target identity is blocked (i.e. Os search for the same item on each trial). If target identity changes on each trial and Os are shown what to search for just prior to each trial, how long does it take to configure the visual system to search for the target? Our prior work has shown that a cue is maximally effective 200 msec after onset if it is an exact copy of the target (e.g. picture of dog #1 cues target picture of dog #1). However, if the cue indicates the type or category (e.g. dog #1 cues dog #2) its maximum effectiveness takes longer to develop. Moreover, such cues are never as effective as an exact cue (Kenner and Wolfe, VSS 03). What happens if the cue is a modification of an exact cue? That is, when does an exact cue become an inexact “type” cue? Os searched an array of photorealistic objects for a different target on every trial. Picture cues preceded the search array by 50, 100, 200, 400, or 800 msec. Cues could be rotated (45, 135, 225, or 315 deg), shrunken (50% smaller), achromatic, or flipped about the vertical axis. Performance was compared to performance using exact cues and to performance in a blocked condition with an unchanging target on all trials. Rotated, shrunken, and flipped cues produced the same results as exact cues. Achromatic cues produced greater error rates and slower RTs but this failed to reach statistical significance. Optimal cueing does not require a precise match between cue and target. It is invariant over substantial changes in size, orientation, and reflection. Only a color change produced a hint of an effect. When searching for “this particular dog”, any of a wide range of views of “this dog” will cue search more effectively than any view of any other dog.
Transportation Security Administration