Organizational and spatial dynamics of attentional focusing in hierarchically structured objects.

Is the focusing of visual attention object-based, space-based, both, or neither? Attentional focusing latencies in hierarchically structured compound-letter objects were examined, orthogonally manipulating global size (larger vs. smaller) and organizational complexity (two-level structure vs. three-level structure). In a dynamic focusing task, participants successively identified the global and local letters in the same trial. Overall response latencies were generally longer for larger versus smaller global objects and for three-level versus two-level object structure, indicating that attentional focusing time increases both with the magnitude of change in attentional aperture size and with the number of traversed levels of object structure. Additional experiments showed that this pattern is unique to tasks that require dynamic attentional focusing. Taken together, the results support a hierarchical object-based-spatial model of attentional focusing.