Abstract
In the change detection task employing visual stimuli with foreground-background segmentation, background changes are often missed while foreground changes are easily detected. Thus, it is believed that attention preferentially allocates to the foreground. The present study investigates the role of top-down attention due to different change probabilities for the foregrounds and the backgrounds and the instructions given. The participants performed change detection tasks that manipulated the instructions (no instruction; divided attention) and the ratios of foreground and background changes (1 : 1; 1 : 5). The results indicate that when the change probability for the background is high and relatively low for the background, or when participants consciously divide their attention to both the foreground and the background, attentional allocation is adjusted between the foreground and the background. The present results suggested that top-down attention influences the properties of attention for foregrounds and backgrounds.
