Three-dimensionality and discriminability in the object-superiority effect

Abstract

Briefly presented target lines are identified more accurately in some contexts of additional noninformative lines than in other contexts (the object-superiority and object-line effects). One explanation for these effects is that the object-like appearance of some contexts (i.e., their three-dimensionality and structural coherence) confers an advantage on the perceptual processing of individual line segments. An alternative explanation is that object-like contexts are simply more discriminable from one another than are other contexts. In the present study, subjects participated in three tasks involving the same set of contexts: tachistoscopic line-identification accuracy (Experiment 1), subjective ratings of three-dimensionality and dissimilarity under a range of exposure conditions (Experiments 1 and 2), and tachistoscopicsame-different accuracy (Experi-ment 3). The main finding was that three-dimensionality and discriminability made equal and independent contributions to line-identification accuracy. Two secondary findings were: (1) that subjective dissimilarity ratings were unreliable indicators of tachistoscopic discriminability, and (2) that line-identification andsame-different performance both supported a noisy-operator model of perceptual representation.