Purchase this article with an account.
Rosemary Behizadeh, Susana T.L. Chung; Category and contour of objects affect the letter ‘B’ Titchener illusion. Journal of Vision 2002;2(7):696. doi: 10.1167/2.7.696.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
The Titchener illusion is an illusion where identical objects are perceived as unequal in size because they are surrounded by objects of a different size. Previous studies concluded that object perimeter and not category or similarity of the internal details between the inducers and the test target influences the Titchener illusion. We hypothesized that these results are the consequence of using arbitrary shapes and objects where the details of the objects are not very meaningful. In this study, we tested whether or not the category and details of objects affect the magnitude of the illusion when the details carry the identity of the objects. To do so, a classic Titchener configuration was used; a reference letter B was surrounded by 4 inducers that were 3 times larger than the reference, and a test letter B surrounded by 4 inducers that were 3 times smaller than the reference. Three categories of inducers were used: letters, numbers and shapes. Within each category, inducers had similar or different contours than the letter B. The size of the test letter B ranged from 5% larger to 7% smaller than the size of the reference, which stayed constant. Observers (N=82) indicated on each trial whether the test letter B was larger or smaller than the reference. The magnitude of the illusion was defined as the point of subjective equality where the size of the test letter B was perceived as identical to the reference. In general, the magnitude of the illusion varied depending on the category of the inducers (from largest to smallest: letters, numbers and shapes). Within each category, inducers that had different contours than the letter B yielded a larger illusion magnitude. Contrary to previous reports, our results suggest that both category and the details of the inducers play a role in inducing the Titchener illusion when meaningful objects are used and the details of the objects convey the identity of the objects.
This PDF is available to Subscribers Only