Question

Why are illusions a useful feature of perceptual systems that can aid in our survival?

Answer 1

• Much of what we think we see is not real – it’s an illusion. A favourite pastime for many visual psychologists and artists is to baffle and confuse our perception by making things appear that are not really there, or manipulating the way that we might see patterns or colours.
• The origin of many illusions lies in the fact that the brain often receives incomplete or conflicting information from the visual system and has to ‘fill in’ or rectify the missing information. Most of the time it gets it right, but sometimes, especially with artificially constructed scenes, it can be misled.
• The first reason why animals may utilise illusions is for defence against predators. Back in the 1970s a series of studies on snakes suggested that particular stripes and zig-zag markings created the impression that a snake was either moving at a different speed, or even in the opposite direction to reality.
• Something about the banding patterns and colours seemed to fool observers into misjudging speed.
• It is perhaps not surprising then that a now famous visual illusion by Kitaoka Akiyoshi, the ‘rotating snakes illusion’, is broadly based on the idea of contrasting bands of colour. These create the very strong impression of movement where none truly exists.
• Illusions are sort of necessary in life. We view our world through our own mental models which are influenced by several factors from experience, culture, exposure etc. These models help us make sense of the lives we are living.
• Adapting is what our species (and all other species) has been doing since day one. Our brain simply looks for ways to help us survive, some banal (find food, eat it), others wildly innovative (use your ears to see).
• This is why active engagement is so important: it taps into a neurological resource that is core to your biology, and can lead to innovations in perception that have a physical basis in the brain, if you know how to exploit it.
• A good example of an optical illusion – one that actually occurs inside the eye – is floaters.Floaters are small specks, spots or shadowy shapes that seemingly float in your field of vision. To some, they look like a bright white snow or flashes of light.
• Floaters are caused by tiny irregularities in the fluid that fills the eye. In other words, they're real. They become more common as one gets older.But nearly every other illusion happens at the brain level, which is why scientists say they shouldn't be called "optical illusions," and why the term "visual illusions" is more appropriate.
• Instead of thinking that you cannot trust your eyes when you see an illusion, you really should be saying, "I cannot always trust my visual system,".The visual system includes not only the eyes but the optic nerve, which links the eye to the brain; and the primary visual cortex, the area of the brain that processes visual information.
• There are other real-world examples of illusions. Pilots might encounter visual illusions while in flight, such as a false horizon, or when landing, such as a narrow runway. They are trained to recognize and ignore these illusions so they can safely fly their aircraft.
• But while some illusions may pose a safety threat, others may actually be used as safety measures. For example, visual illusions have been used to control drivers' speed on a hazardous curve. Stripes on the road are painted closer together as drivers approach the sharpest part of the curve. The illusion makes drivers think they're speeding up -- so they slow down and, it's hoped, have fewer accidents.
• The brain is always constructing things, which is helping you survive. Some of these constructions can be fiction.