Visual orientation illusions

Global mechanisms involved in hierarchical effects and frames of reference

Roberta Daini*, Peter Wenderoth, Stuart Smith

*Corresponding author for this work

Research output: Contribution to journalArticle

7 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)770-778
Number of pages9
JournalPerception and Psychophysics
Issue number5
Publication statusPublished - Jul 2003

Cite this