Uniform TitleThe role of part structure in the perceptual localization of a shape
NameDenisova, Kristina (author), Singh, Manish (author), Kowler, Eileen (author), National Science Foundation, United States. Air Force. Office of Sponsored Research,
Center of mass,
Saccadic eye movements
DescriptionThe process of object localization may be accomplished with respect to a particular
reference location, such as the center of gravity, COG (eg Vishwanath and Kowler, 2003 Vision
Research 43 1637-1653). Here, we investigated how part structure affects an object's reference
location. The reference location was evaluated with a measure of the illusory displacement of an internal target element embedded within a larger object (Morgan et al, 1990 Vision Research 30 1793-1810). To examine whether the reference location is different for shapes with part structure, two shapes were tested: circle (small and large; no part structure) and bell (shape with two parts, one larger than the other). Results were examined with respect to two predictions: either the location of an object is based on its shape as a whole, disregarding part structure (ie a single, overall COG), or the parts are processed separately (different COGs).
With the circles, the results showed a systematic illusory displacement of the internal target toward the COG. With the bell, the illusion was significantly weaker than with both circles--even though the main part of the bell had the same size as the small circle, and its horizontal axis had the same extent as the large circle. Moreover, the distance judgments for the bell were consistent with a (weaker) reference point being located at the COG of the larger part, rather than at the COG of the entire bell. These results show that the part structure of a shape plays a role in the representation of its location, and that for complex shapes the perceived location of an embedded element depends more on the parts within which it is embedded, rather than on the whole shape.
NoteDenisova, Kristina, Manish Singh, Eileen Kowler, 2006. The definitive, peer-reviewed and edited version of this article is published in Perception, 35, 1073-1087, DOI:10.1068/p5518.
NotePerception, 35, 1073-1087
NoteSupported by the Air Force Office of Scientific Research, Grant AF 49620- 02-1-0112, Life Sciences Directorate to Eileen Kowler, and by NSF, Grant BCS-0216944 to Manish Singh.
NoteAF 29620-02-1-0112; to Eileen Kowler
NoteNSF BCS-0216944; to Manish Singh
CollectionKowler, Eileen Collection
Organization NameRutgers, The State University of New Jersey
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