Tag Archives: Visual Consciousness

Mysteries of the Brain – Visual Consciousness

I got several questions and comments on this VERITAS. Posting a few of them:

Apurva Kalia wrote:

“How have these numbers been calculated in some manner?
Is there a way to determine the CPU speed of the visual cortex?
How does one define the no. of bits needed to form conscious awareness?”

My answer:
These are excellent questions and I tried to find the answers. Could manage to find some stuff but not a lot. Scientists took a guinea pig retina and placed it in a dish. They showed it different movies. They connected 7 different types of ganglion cells in the retina to electrodes. The different ganglion cells present different pictures to the brain which then creates the overall pictures. The response time of each cell was measured by the number of electrical spikes per second in the electrodes when seeing the movie.
For more details see:


There is an article by Zimmerman called “the nervous system in the context of information theory” in the book “Human physiology” by R. F. Schmidt & G. Thews. We need access to this article to answer Apurva’s questions in detail. I do not have it yet. I will try to get it.

Rakesh Malik wrote:

” FYI — sum total of all the sensory inputs is ~ 11 Mbps. ( this is a number from a journalist and have not been able to corroborate it with published numbers in peer reviewed journals)

Erik Panu wrote:
Hence, why the whole area of metaphysics is popular… and why this movie was interesting to see; see the “Academic Reaction” part of this link in particular:


Mysteries of the brain – Part 21 : Visual Consciousness



            This is going to be a very short VERITAS mail. There is something incredibly interesting that I read yesterday and I really wanted to share that with people.

            There is a huge amount of external stimulus that reaches our senses every second. It is estimated that about 10 billion bits(10,000,000,000) of visual information reaches our eyes every second. But the eye has its limits. The optic nerve at the back of the retina can transport only 6 million(6,000,000) bits per second to the brain. The visual cortex in the brain processes only about 10,000 bits per second.
And the no of bits that go to form the conscious awareness of what is being seen is only 100 bits per second.

So though we are able to see 10 billion bits every second through our eyes, our perception of what is being seen is formed by only about 100 bits per second: an insignificant amount of information! So the perception of reality is only triggered by the external stimulus: most of it is formed within the brain. We see a little and we make up a huge amount. This is related to  what Aakanksha told us in :
“VERITAS: Mysteries of the Brain Part 20: Hypnosis”

This applies to all senses. We take very little from the outside word- we make up most of our perceived reality. 
John Milton said ” The mind is its own place, and in itself, can make heaven of Hell, and a hell of Heaven.”


Go, wondrous creature! mount where Science guides:
Go, measure earth, weigh air, and state the tides:
Instruct the planets in what orbs to run,
Correct old time and regulate the Sun;

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Veritas by Kanwarpreet Grewal is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License.