Similar mechanisms underlie simultaneous brightness contrast and grating induction

Area of Science:

• Visual perception
• Computational neuroscience
• Image processing

Background:

• Grating induction (GI) and simultaneous brightness contrast (SBC) are fundamental visual phenomena.
• Understanding the underlying neural mechanisms is crucial for visual science.
• Previous models have not fully explained the range of brightness induction effects.

Purpose of the Study:

• To determine if the mechanisms of grating induction (GI) can also explain simultaneous brightness contrast (SBC).
• To quantitatively assess how test field dimensions influence brightness and darkness induction.
• To propose and validate a computational model for brightness induction.

Main Methods:

• Conducted point-by-point brightness matching experiments with human subjects.
• Varied test field height (1, 3, 6 deg) and width (1-32 deg).
• Compared experimental data to predictions from a novel weighted difference-of-Gaussian filter array model.

Main Results:

• Brightness and darkness induction structure was present in wider fields, aligning with GI predictions.
• Induction amplitude decreased and reversed (cusping) with decreasing test field width.
• Overall induction decreased with increasing test field height, but relative brightness increased with decreasing width.

Conclusions:

• A weighted array of difference-of-Gaussian filters, including low spatial frequencies, parsimoniously explains brightness induction.
• This model accounts for various phenomena, including GI, contrast/assimilation, and the Hermann Grid illusion.
• The filter array model offers a physiologically plausible explanation for brightness perception.