Abstract

It is easy to detect a small change between two sequential presentations of a visual stimulus, but, if they are separated by a blank interval, performance is around chance. This change blindness (CB) can be rectified, or improved, by cueing the spatial location of the change either in the first stimulus or the interval; however, no advantage is conferred when the cue appears during the second presentation of the stimulus. This supports the idea that a representation of the first stimulus is formed and persists through the course of the interval before being 'overwritten' by the second presentation of the stimulus (Landman et al, 2003 Vision Research 43 149 - 164). We were interested in the time course of the cueing effect during the interval. Following Landman et al, our first stimulus was an array of eight rectangles defined by texture and there was a 50% chance that one of the rectangles would change orientation in the second stimulus. Five cues were used, one within the first stimulus, three across the interval, and one in the second stimulus. Only one of these cues appeared in each trial. The cued rectangle was the one that would change between the first and second stimulus when a change occurred. The cue was a yellow line. Eighty-five observers showed the characteristic cueing performance supporting 'overwriting', but performance decreased over the duration of the interval suggesting that the initial representation of the first stimulus fades over time. However, when the size of the rectangles was increased, performance across the interval improved significantly. We consider two possible explanations: one is that simply by increasing rectangle size we raise the storage capacity for the number of rectangles in our representation, the other is that storage is related to task difficulty.