People can actually see SOUND. Researchers have found out that, in some cases, when the part of the brain devoted to sight is small, some people may actually see sound.  These findings point to how the brain may sometimes use this strategy when vision is undependable.

This phenomenon was noticed when scientists took a better look at what is called sound-induced flash illusion.  This is when a single flash is followed by two bleeps, people sometimes also see two flashes.

Benjamin de Haas, a neuroscientist at University College London, says, “Some would experience it almost every time a flash was accompanied by two bleeps, others would almost never see the second flash”.  This proves that there are strong differences among different people with regard to being prone to this illusion.

De Haas and his colleagues say these differences are caused by variations in brain anatomy.  To confirm these observations, they used Magnetic Resonance Imaging (MRI) to analyze the brains of 29 volunteers and tested them with flashes and bleeps.

Results showed that the smaller a person’s visual cortex, which is the part of the brain linked with vision, the more that person experienced the illusion.

De Haas told Live Science, “If we both look at the same thing, we would expect our perception to be identical. However, our results demonstrate that this not quite true in every situation — sometimes what you perceive depends on your individual brain anatomy.”

The researchers suggest that this is the way the brain adjusts when vision is imperfect.

De Haas’ explanation of this is, “If this speculation holds, it would make perfect sense for smaller visual brains to make more use of the additional information provided by the ears. In the real world, sources of light and sound are often identical, and combining them will be advantageous. Imagine you take a twilight walk in a forest and scare up some animal in the undergrowth. The best strategy for finding out whether you are dealing with a hedgehog or a bear will involve combining visual information, like moving twigs and branches, with auditory information, like cracking wood.”

The phenomenon of this illusion is not yet fully understood.  Only about ¼ of the differences can be explained by brain anatomy.  De Haas admits the rest cannot yet fully be explained.

The McGurk effect, is another illusion wherein the visual cue of one sound is paired with auditory cue of another and some people mysteriously perceive a third sound.

Sight seems to be an accurate way of perceiving stimulus but it seems that it is not all that accurate.  It is affected by so many differing factors such as hearing and brain anatomy.  Researchers like de Haas now question what else could be affecting such senses?
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Reference Credit | Islandcrisis