  This paper explores the tilt illusion effect in the Cafe Wall pattern using a
classical Gaussian Receptive Field model. In this illusion, the mortar lines
are misperceived as diverging or converging rather than horizontal. We examine
the capability of a simple bioplausible filtering model to recognize different
degrees of tilt effect in the Cafe Wall illusion based on different
characteristics of the pattern. Our study employed a Difference of Gaussians
model of retinal to cortical ON center and/or OFF center receptive fields. A
wide range of parameters of the stimulus, for example mortar thickness,
luminance, tiles contrast, phase of the tile displacement, have been studied.
Our model constructs an edge map representation at multiple scales that reveals
tilt cues and clues involved in the illusory perception of the Cafe Wall
pattern. We present here that our model can not only detect the tilt in this
pattern, but also can predict the strength of the illusion and quantify the
degree of tilt. For the first time quantitative predictions of a model are
reported for this stimulus. The results of our simulations are consistent with
previous psychophysical findings across the full range of Cafe Wall variations
tested. Our results also suggest that the Difference of Gaussians mechanism is
the heart of the effects explained by, and the mechanisms proposed for, the
Irradiation, Brightness Induction, and Bandpass Filtering models.
