Abstract
Research on dynamic attention has shown that object-based attention can remain allocated to temporarily invisible objects (e.g., Flombaum, Scholl, & Pylyshyn, 2008). Does this hold even if objects in scenes are displaced by scene motion? In two experiments we examined the role of information about scene motion in multiple object tracking (MOT). In brief intervals of object invisibility, we introduced mid-trajectorial smooth and abrupt viewpoint-changes. In control conditions, all objects were visible. Smooth viewpoint-changes provided continuous information about scene motion, which supported in tracking temporarily invisible objects. However, abrupt and therefore discontinuous viewpoint-changes during object-invisibility strongly impaired tracking performance. Retained object locations that are linked to scene elements can account for attentional tracking that follows invisible objects through continuous scene motion. In control conditions, we replicated previous findings: If objects were visible throughout the trial, abrupt but not smooth viewpoint-changes disrupted MOT performance. Not surprisingly, abrupt viewpoint-changes disrupted performance as well if objects were temporarily invisible.
The novel evidence obtained in the reported experiments pertains to smooth viewpoint-changes that occurred while objects were invisible. Performance was superior than with abrupt viewpoint-changes suggesting that continuous information about scene motion supported in updating the retained locations of invisible objects. Current theories of MOT remain silent about the use of scene information in tracking (e.g., Pylyshyn, 2007). We suggest a tracking mechanism for temporarily invisible objects in scenes undergoing viewpoint-changes with foci of split attention following targets. These foci are linked to scene elements. Thus, they remain in place when objects disappear and follow continuous scene motion. Multi-focal attention may be pictured as peaks on an attentional map overlaying the visible scene and following scene motion if motion is continuous.