Abstract
The conditions under which selective attention is object-based are affected by the perceptual organization of the scene. Previous work has examined perceptually grouped object-based effects as evoked by detection tasks (expt 1 Marino & Scholl, 2005; expts 1-3 Avrahami, 1999) or simple luminance/distance/texture discrimination (expt 2 Marino & Scholl, 2005; expt 4 Avrahami, 1999l; Kramer & Jacobson, 1991). Here, we use flanker compatibility measures (Eriksen & Eriksen, 1974) to quantify object-based selective attention in two contexts: one in which the targets of attention appear within closed object shapes, and another in which the shapes are not closed. In Experiment 1, a vertical rectangle at screen center was flanked by four identical rectangles, 2 to the left and 2 to the right (rectangles condition). An exogenous cue then appeared outside of either end of the central rectangle. A set of 10 target/distracter letters were presented, two letters in each rectangle (one on each end). One of these letters (the target) was colored green (or orange, for half the subjects), the other nine (distracters) were white. Subjects performed a letter discrimination on the target. The central distracter was neutral, congruent, or incongruent with the target; and the flanking distracters were either congruent or incongruent with the target. In the lines condition, the horizontal "connectors" that formed the top/bottom of each rectangle were removed, forming 10 vertical lines. Results showed that flankers only have effects when the target and distracters lie on a contiguous region. In Experiment 2, we removed the exogenous cue from the procedure of Experiment 1, alleviating the object-based capture of attention prior to target onset. There was no difference in compatibility effects as a function of object closure, suggesting that object-based attention capture (promoted by an exogenous cue) is critical to the effect of object closure on selective attention.
Meeting abstract presented at VSS 2013