REVERSING VISUAL-SEARCH ASYMMETRIES WITH CONJUNCTIONS OF MOVEMENT AND ORIENTATION

Many theories of visual search offer general principles intended to apply to search for targets defined by any stimulus attribute. The importance of considering specific properties of different visual subsystems is demonstrated by examining search for movement-orientation conjunctions. In displays of intermingled moving and stationary stimuli, search for a salient tilted target (45-degrees vs. vertical) is easier among moving than stationary stimuli. If a finer orientation distinction is required (9-degrees vs. vertical). the reverse is true; search is easier among the stationary. This follows from the known properties of visual subsystems specialized for processing moving or stationary stimuli. It is not predicted by general theories of visual search such as guided search or similarity theory, nor by principles of Gestalt grouping.