Attention and perceptual organization: what the object effect reveals about the representation of objects in the visual system

This study explored the representation of objects in the object-based attention system in terms of how the system incorporates cues based on perceptual organization. Uniform connectedness is an organizing principle thought to underlie the segregation of the visual field into figure and ground, and ultimately into separate objects. At what point does object-based attention begin to have an influence as processing progresses fromuniformly connected (UC) regions to objects? To address this question, this experiment explored a boundary condition of the object effect in terms of perceptual organization with two different types of UC stimuli: silhouettes of two recognizable objects (Experiments 1 and 2a) and self-splitting figures (Experiment 3a). Object-based attention may process a UC stimulus as a single object, as the bottom-up information indicates, or it may process it as two separate objects, as the silhouettes and splitting figures are perceived. Two different tasks, discrimination (Experiment 1) and detection paradigms(Experiments 2 and 3), were used to achieve convergent validity.