Why are visual sine gratings so useful as stimuli for researching vision?
a) Sine gratings represent clear and distinct contrast between light and dark regions, which is what we usually find in the natural world.
b) Sine gratings represent fuzzy boundaries (gray areas between light and dark regions), which are common in the natural world.
c) The visual system breaks down images into a number of square wave components, which can be analyzed using Fourier analysis.
d) All the above