Fooling the Brain

How Ventriloquists Trick The Brain: Sight, Sound Processed Together And Earlier Than Previously Thought

Does Your Brain Play Tricks On You? Note, this one doesn't look very scholarly, but it is relevant.

I always find it interesting when things "fool"our brains, like this link that Steve posted a few days ago with a myriad of optical illusions. The first article here talks about a recent discovery in sensory processing. The article from Science Daily relates a discovery by the Duke University Medical Center which apparently did much of its work on chimpanzees, but is extrapolating their findings to humans as well. They discovered that there is sensory integration much earlier than previously thought. Before, scientists believed that sensory information coming in through the eyes or ears was sent virtually separately to the cortex where the information was integrated and we made sense of it.

However, their new discovery suggests otherwise. Their work focused on a very small brain region in a very primitive part of the brain (primitive in the sense that it is thought to have evolved a very very long time ago relative to the evolution of our cortex and other higher processing centers) called the inferior colliculus. The article claims that this early combination of sensory information is what causes us to perceive ventriloquism as realistically as we do. This can also be applied to movies: even though the speakers producing the sound are at the sides of the screen or behind the receiver, the receiver perceives the voice as coming from the mouth of the actor or actress on the screen. It also seems to be a process that magicians take advantage of.

What the larger psycholinguistic ramifications of this are, I'm not entirely sure, but it does lead me to some questions. Firstly, what evolutionary significance does this have? Does processing and integration that happens earlier in the cognitive process save the higher regions of the brain from having to bother with it, making us more efficient? That is, is it better the we automatically perceive the growl of a predatory animal and the sight of a predatory animal as originating from the same beast rather than thinking about them separately? Is it just brain economics? Or does this earlier processing an evolutionary structure that benefitted earlier, more primitive brains which didn't have much of a cortex at all, and the inferior colliculus did the integration for whatever higher system sensed it?

Whatever the causes or reasons (or lack thereof), I find it fascinating when we humans devise ways of fooling each other, of tricking our brains. How it is done and for what reasons we are evolutionarily inclined to be susceptible are very interesting questions to me, and have larger ramifications for society such as using eyewitness testimony as rock hard evidence in court when the senses can be fooled fairly easily.