van Eccelpoel C, de Graef P, Verfaillie K, 2000, "Semantic effects on the detection of intrasaccadic changes of object orientation and position" Perception 29 ECVP Abstract Supplement
Semantic effects on the detection of intrasaccadic changes of object orientation and position
C van Eccelpoel, P de Graef, K Verfaillie
Verfaillie et al (1994 Journal of Experimental Psychology: Learning, Memory and Cognition 20 649 - 670) found that whereas intrasaccadic changes in in-depth-orientation of a point-light walker were easily detected, intrasaccadic changes in image-plane position were not. This is because transsaccadic integration subserves object identification, and object orientation, unlike object position, is an integral part of the viewpoint-dependent object representations that are matched to achieve identification. Boucart and Humphreys (1997 Perception 26 1197 - 1209) found that object semantics interfered with object matching whenever matching required a global shape judgment. This is because shape is an integral part of the representations in the object lexicon which interfaces object identity and semantics.
Combining these findings, we hypothesised that object semantics should interfere with the detection of intrassaccadic changes in object orientation, but not in object position. To test this, viewers performed saccades from one object to another and had to detect intrasaccadic changes in the position or orientation of one of the objects. The objects were categorically related or unrelated. As predicted, semantics interfered with the detection of a change in orientation, but not of a change in position. Moreover, interference was strongest for related foveal and extrafoveal objects in similar orientations. We conclude that transsaccadic object perception is mediated by an object lexicon containing orientation-dependent but position-independent representations.
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