20.05.2014

Torsten Betz: New abstract accepted as a poster at ECVP from 24.08.-28.08.2014

Title: "Testing the ODOG brightness model with narrowband noise stimuli", Authors: Torsten Betz, Felix Wichmann, Robert Shapley, Marianne Maertens

Abstract:

Testing the ODOG brightness model with narrowband noise stimuli

The oriented difference of Gaussians (ODOG) model (Blakeslee and McCourt, 1999) computes the perceived brightness of an image region through the operation of orientation and frequency selective filters. The model successfully predicts the brightness of test regions for a number of brightness phenomena, including White’s illusion.

Salmela and Laurinen (2009) showed that masking White's illusion with narrow-band noise affects the strength of the illusion. The effect of the narrow-band noise mask depended on its spatial frequency and orientation, suggesting that orientation- and frequency-selective mechanisms are important for generating the illusion. The ODOG model is comprised of orientation- and frequency-selective mechanisms, and thus the effect of narrow-band noise on its output is a critical test of its adequacy as a mechanistic account of White’s illusion. We analyzed the effects of narrow-band noise on the output of the ODOG model. The orientation of the noise had a similar effect on model and human performance, but the model was much more sensitive to the noise than were human observers. Furthermore, the model was sensitive to noise at low frequencies, where observers were unaffected. We explain the discrepancies through a detailed analysis of the individual components and computational steps of the model.