Can other visual patterns trigger seizures?
Besides flickering light, there are also specific spatial-contrast patterns which can be seizure-provoking. In general, high contrast light and dark bars are provocative (if there are between one and four black and white bars in each degree of the person’s vision). The light-dark contrast is critical to abnormal brain response; red-green bars, stripes or patterns are non-provocative. Bars or gratings that oscillate (white to black and vice versa) are more provocative than static patterns, especially if the patterns oscillate in the “dangerous” frequency of 15 – 20 Hz. “Dartboard”, sectored or “whirling wheel” type patterns maximally stimulate the visual cortex and are therefore more provocative, especially when they cover a large proportion of the picture area.
