The role of bbject discontinuity in object-based selection

Abstract

Experiment 2 was similar to Experiment 1 with the following exceptions. Half the trials consisted of one object displays and half the trials consisted of two object displays. On each trial, the discrimination target (the “X” or “O”) appeared at one of three possible locations: at the cued location (valid condition, 67% of trials) or at one of the two other invalidly cued locations (invalid across ere are a eas wo ypo eses o ow a en on s rec e o o ec s an object-based effects are generated: (1) The effect of objects on attentional selection is due to a cost associated with either dividing or switching attention between discrete object representations (Egly et al., 1994; Lamy & Egeth, 2000) (2) Object effects arise because the spread of attention is constrained by object boundaries (grouped array hypothesis, Vecera, 1994). Critically, the former hypothesis requires two separate object representations for object-based effects to emerge, while the latter requires only object discontinuity or a disruption in Experiment 3: Results either one object or two objects in the display. The method was identical to Experiment 2, except participants were required to respond at the beginning of each trial whether the display consisted of one object or two objects. The data report, below, includes only trials on which the participants correctly reported the number of objects in the display (mean accuracy = 99.1%). Object, 1000 ms Cue, 50 ms , ms