Abstract
An object advantage is found when comparing object-based shifts of attention within an object versus space-based shifts over the same distance across objects. Theoretical accounts have included both an advantage for object-based shifts due to the spread of attention within an object and a disadvantage for space-based shifts across objects due to attention having to disengage before shifting. This study examines the effects of two spatial factors, size and distance, on the object advantage as a means of exploring these theoretical perspectives. Experiment 1 manipulated the ratio of within-object to between-object distance using bracket stimuli. Experiment 2 used bar stimuli that fit entirely within the fovea. Methods. Stimuli for Experiment 1 were pairs of brackets (e.g., [ ]) with within-object to between-object distance ratios of 2:1, 4:1, and 6:1. Stimuli for Experiment 2 were pairs of bar stimuli subtending 1.75o with within-object to between-object distance ratios of 1:1. In both experiments the retinal distance between cue and targets was always the same. Attentional cues appeared briefly at one end of one of the members of a pair each trial. On 20% of the trials no target appeared. The cues were valid on 75% of the trials when a target appeared and invalid for the rest. On invalidly cued trials, the target appeared equally often in either the same stimulus or else the other stimulus of a pair. Participants responded as quickly as possible to the onset of the target. Results. Both experiments found faster RTs for valid compared to invalid trials and faster RTs for invalid trials requiring within-object compared to between-object shifts of attention (i.e., an object advantage was always evident). Conclusions. Neither of the spatial factors manipulated, within object distance nor foveal presentation, eliminated the object advantage in a spatial cuing paradigm. The results seem most consistent with a disengaging account of the object advantage (e.g., Lamy & Egeth, 2002).