Observers identified a briefly flashed line segment more accurately when it was part of a drawing that looked unitary and three-dimensional than when the line was in one of several less coherent flat designs.

Recently metacontrast has been described as a case of "impossible" apparent motion. Kahneman (J 967)

No abstract

No abstract

In a series of four experiments, observers identified a briefly flashed line segment more accurately when it was part of a drawing that looked unitary and three-dimensional than when the line segment was presented alone. This extends earlier findings of better identification of a line segment when it is part of an apparently unitary, three-dimensional drawing than when it is in a less coherent flat design; and these results demonstrate a visual effect analogous to the word-letter effect which uses nonlinguistic materials. Experiment 1 demonstrates the existence of the object-line effect and shows that it does not depend on the presence of a subsequent mask; Experiment 2 shows that the effect holds up with two-alternative forcedchoice presentation; Experiment 3 demonstrates that the effect is not due to bright endpoints which may occur when the target line appears with a context; and Experiment 4 shows that the effect is as strong when the target line segments occupy widely separated spatial locations as it is when they occupy nearby, potentially confusable locations. Weisstein and Harris (1974) reported data establishing the existence of an "object-superiority effect" in visual perception, analogous to the "word-superiority effect": Just as a letter is generally perceived better when part of a word than when part of an unpronounceable, meaningless string of letters (Baron & Thurston, .1973;Egeth & Gilmore, 1973;Johnston & McClelland. 1974;Reicher, 1969;Smith & Haviland, 1972), so a line segment was found to be perceived better when part of a drawing that looked unitary and three-dimensional than when it was in one of several less coherent, flat designs.' This basic finding has now been replicated in several different laboratories (McClelland, in press;Womersley, 1977; Klein, Note 1; Spoehr, Note 2).However, there was one distinct difference between the results with drawings and with words: Whereas a letter in a word is typically perceived better than the same letter in isolation-the "word-letter effect" (Johnston & McClelland, 1973; Matthews, Weisstein, & Williams, 1974;Reicher, 1969; Wheeler, 1970)-Weisstein andHarris (1974) reported finding in pilot studies that their target line segments were detected better when presented alone than when part of a coherent pattern. That is, under the conditions used in their study, there was no evidence for an "object-line effect" analogous to the "word-letter effect."?This research was supported in part by National Eye Institute Grant NIH ROI EY01330 and National Science Foundation Grant BNS 76-02059 to the second author. We would like to thank Irving Biederman, Charles S. Harris, and James L. McClelland for helpful comments on various drafts of this paper. Requests for reprints should be sent to Naomi Weisstein, Department of Psychology, State University of New York at Buffalo, 4230 Ridge Lea Road, Buffalo, New York 14226. 85We now present evidence for the existence of an object-line effect, thereby extending the analogy between object and word perception, and opening fur...