Groundbreaking research on this optical illusion could unlock a new understanding of how our eyes and brain work together, by ndaviden
to show that color afterimages can be produced entirely by higher-level cortical mechanisms. In their first experiment, 100 participants were screened for suggestibility using the Harvard Group Scale of Hypnotic Suggestibility: Form A .
Once the hypnotized participants confirmed they were seeing red, they were instructed to keep looking at the"red" screen for another 30 seconds. Afterward, a new, slightly lighter gray screen appeared, and participants were asked to quickly name the color they saw.
Then, when a second gray screen was presented, they reported any color they saw. Although all 15 participants reported being successful at imagining red, only five reported seeing a blue or green aftereffect in the second gray screen; another five reported seeing pink , and the remaining five reported seeing just a shade of gray.