Orienteering for the Visual System

Why are gratings such popular stimuli in studying visual perception?

Gratings are popular stimuli because they can be used to explore one of the key characteristics of the visual system: orientation preference. Both retinal ganglion cells and visual cortical neurons may show topographical preference for specific orientations of stimuli. Orientation preference is founded on the ability of receptive fields to detect lines and edges; when you have a line or an edge, you can have a slant (a certain angle of orientation). And the detection of lines and edges are based on the grouping of ON- and OFF-center ganglion cells. Overall, gratings test a fundamental ability of the visual system that is based on a few other fundamental abilities of the visual system.

Furthermore, there are some interesting characteristics of orientation preference that have been discovered and evoke further questions. For example, discovery of the oblique effect led to the realization that humans “see” vertical and horizontal lines better than oblique lines. This begged the institutional question of nature vs. nurture: does the oblique effect arise from environmental conditioning, genetic predisposition, or both? Probably both. Further exploration of visual orientation will hopefully lead to further questions, discoveries, and innovations.