Losing the trees for the forest in dynamic visual search

Abstract

Representing temporally continuous objects across change (e.g., in position) requires integration of newly sampled visual information with existing object representations. We asked what consequences representational updating has for visual search. In this dynamic visual search task, bars rotated around their central axis. Observers searched for a single episodic target state (oblique bar among vertical and horizontal bars). Search was efficient when the target display was presented as an isolated static display. Performance declined to near chance, however, when the same display was a single state of a dynamically changing scene (Experiment 1), as though temporal selection of the target display from the stream of stimulation failed entirely (Experiment 3). The deficit is attributable neither to masking (Experiment 2), nor to a lack of temporal marker for the target display (Experiment 4). The deficit was partially reduced by visually marking the target display with unique feature information (Experiment 5). We suggest that representational updating causes a loss of access to instantaneous state information in search. Similar to spatially crowded displays that are perceived as textures (Parkes, Lund, Angelucci, Solomon, & Morgan, 2001), we propose a temporal version of the trees (instantaneous orientation information) being lost for the forest (rotating bars).