title: Visual orientation illusions: global mechanisms involved in hierarchical effects and frames of reference.
abstract: Five experiments were conducted in order to determine which of two hypotheses, initially proposed by Rock (1990), accounts for interactions between oriented elements in a visual scene. We also explored the suggestion that two hypothetical processes--namely, frame of reference and hierarchical organization--describe phenomena arising from distinct mechanisms (Spinelli, Antonucci, Daini, Martelli, & Zoccolotti, 1999). Double inducing stimulus versions of one-dimensional and two-dimensional tilt illusions, the rod-and-frame illusion, and combinations of these were used. Our data suggest that both hypotheses can predict orientation interactions in conditions in which only one mechanism--namely, the global visual mechanism of symmetry axes extraction (Wenderoth & Beh, 1977)--is activated. Which hypothesis is appropriate to predict the perceived orientation depends on some physical features of the objects.
authors.affiliation: Department of Psychology, Università degli Studi di Milano-Bicocca, Milan, Italy. roberta.daini@unimib.it
authors.forename: Roberta
authors.initials: R
authors.lastname: Daini
authors.forename: Peter
authors.initials: P
authors.lastname: Wenderoth
authors.forename: Stuart
authors.initials: S
authors.lastname: Smith
mesh_terms: D004192:Discrimination, Psychological; D005133:Eye Movements; D005260:Female; D005403:Fixation, Ocular; D006801:Humans; D008297:Male; D009903:Optical Illusions; D014796:Visual Perception