Crash in visual processing is not due to defective eye sight

Many things come into our eye sight, but we really don’t see some of them. Some say, it is because of some problem with the eye sight. Some other say, your mind is pre-occupied with something elese. And some would say even that you don’t have the presence of the mind.

But the neuroscientists from Georgetown University have a different explantion. It is nothing to do with our eyesight. This is called “crash in visual processing” — a bottleneck of feedforward and feedback signals that can cause us not to be consciously aware of stimuli that our brain recognised.

In the Journal of Vision, investigators point out that it can happen when the brain

is asked to process more information than it can handle. Then the neurons which is busy processing one image are tasked with processing another too quickly, and then either one or both images do not reach conscious awareness.

“Prior studies have shown that people are rather poor at detecting objects of interests that appear close together in time, even though the human brain can process up to 70 images per second,” says the study’s senior investigator, neuroscientist Maximilian Riesenhuber, PhD, a professor of neuroscience at Georgetown University Medical Center.

“Our study shows a specific limitation of the visual system and explains why our consciousness cannot keep up. When someone tells you they didn’t see something that occurred in a chaotic situation, maybe they did, but they didn’t know that they did.”

The study provides evidence for the theory that a bottleneck can occur in the neuronal pathway that takes in visual stimuli. That pathway starts at the back of the brain and extends forward, rapidly processing the visual signals up to the frontal cortex (“feed forward”), and then sending them back again to the areas the stimuli were first processed in (“feedback”).

“The feedback wave appears to be crucial for participants to actually become conscious of the stimuli their brains had processed in the ‘feedforward’ pass,” Riesenhuber explains.

The crash in visual processing happens when the back of the brain is stimulated again with a second image before the feed forward and feedback loop needed for the first image is completed, Riesenhuber explains.


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