Presence and Absence of Top and Right Advantage as an Indication of the Attentional Strategies Underlying Object Selection

To explore the conditions in which an object is selected in its entirety and better understand the process underlying such selection, a target, lying on the contour of an outline figure, was judged. Target position on the figure was either known or not known throughout a block of trials, and various properties of the figure itself—continuity, familiarity, and contrast—were manipulated. The pattern of results can best be accounted for by assuming that object selection involves a scan, beginning at the top-right end and terminating only when the bottom-left end is reached. Partial selection could have occurred only for the top and the right positions when the target was known always to be there. As to the manipulated properties, none interacted with knowledge of target position, indicating that they did not affect the process of selection. Most importantly, partial selection was not facilitated even in the discontinuous condition, in which the figure consisted of two separate elements.