An unbinding problem? The disintegration of visible, previously attended objects does not attract attention.

In seven experiments, observers searched for a scrambled object among normal objects. The critical comparison was between repeated search in which the same set of stimuli remained present in fixed positions in the display for many (>100) trials and unrepeated conditions in which new stimuli were presented on each trial. In repeated search conditions, observers monitored an essentially stable display for the disruption of a clearly visible object. This is an extension of repeated search experiments in which subjects search a fixed set of items for different targets on each trial (Wolfe, Klempen, & Dahlen, 2000) and can be considered as a form of a "change blindness" task. The unrepeated search was very inefficient, showing that a scrambled object does not "pop-out" among intact objects (or vice versa). Interestingly, the repeated search condition was just as inefficient, as if participants had to search for the scrambled target even after extensive experience with the specific change in the specific scene. The results suggest that the attentional processes involved in searching for a target in a novel scene may be very similar to those used to confirm the presence of a target in a familiar scene.