Post #8: Optical Illusions

Optical illusions are fascinating because they are almost like magic. These illusions take advantage of the way that our brain perceives visuals. David Hubel and Torsten Wiesel won the 1981 Nobel Prize in Physiology or Medicine for their discoveries about how the brain interprets the information sent to it from the eyes. They discovered that there is a step by step process in how the brain analyzes what the eye sees. Each neuron in the brain is responsible for a specific detail in the pattern of the image. But even with Hubel and Wiesel's discoveries and our knowledge of the different parts of the brain that deal with color, form, motion and texture, scientists still don't entirely understand how all the messages come together to produce our overall perception of an object. In fact, once we've seen the "trick" in an optical illusion, it is almost impossible to un-see it. We are unable to transport our minds back to a time when we didn't know the thing we just learned. The most successful optical illusions use line and perspective to trick the eye. For example, there is an optical illusion where there are black squares surrounded by white lines. Where these white lines intersect at the corners of the black squares there appears to be a dark grey circle. This is created by the phenomenon in which the receptor cells that take in the information provided by the white lines and receptor cells carrying information about the black squares combine and create a faulty data, in a way, to the neural ganglia that then transmits the vision to the brain. Another example of how our brain can be easily tricked is through the principle of proximity. In this principle the brain’s desire to resolve ambiguous images into unambiguous ones, by using nearby visual cues to provide context and pattern. This effect is intensified when the viewer unfocused their eyes on the image. Optical illusions similar to the first image shown in this post are particularly interesting images because they not only trick your eye into seeing something that is not there. But it tricks your eye into thinking that it is moving. Through the use of curvature and color and shape, images that are static give the appearance of motion. This may be due to a cognitive interpretation in the brain triggered by the edges between the black and white or possibly by the way that our brains perceive the transition from light to dark as motion. Optical illusions like this one can move in different directions depending on the viewer at any given time. They are fascinating and scary at the same time in the sense that we can be looking at something that is real, however our own brain fails to interpret said image or item correctly. Therefore, our own eyes and brain are giving us false information.