Blind, Yet Able to See?

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Have you ever wondered if it is possible for "blind" people to see anything? It has to do with the phenomenon of Blindsight, the instance in which blind people that have damaged a specific area of their cortex still have the ability of guessing correctly about their visual surroundings. blindsight man navigates obstacles.jpg

The man in the above picture has the psychological condition of Blindsight. The man started at the end of the hallway and proceeded to walk down the hallway, all the while maneuvering around placed obstacles on the ground. Also, a psychologist asked some "cortically blind" subjects to identify stimuli as either vertical stripes or horizontal stripes. These same subjects were able to answer with "better-than-chance" levels correctly, even after reporting they saw nothing at all.

But How? How are they able to do this? It is because these people have suffered damage to their primary visual cortex, stopping the route to visual association. "Coarser visual information still reaches the visual association cortex through an alternative pathway that bypasses V1. This visual information probably accounts for blindsight"(Moore et al., 1995; Stoerig & Cowey, 1997; Weiskrantz, 1986). It is this info that passes through the alternative pathways that allow for people like the man in the image to do the things they do.

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This is really interesting! It's amazing how people who are considered legally blind still seem to have sense of what is around them anyways. It was really helpful for you to provide that information at the bottom of your post- it provided a lot of insight. Hopefully information like this will pave the way for medicine to help those without sight to see again.

I always see people around campus, that I assume are blind, navigating their way through crowds of people and narrow sidewalks. I've always wondered how they're doing that, but with the arguments presented in your blog post, I have my answer! It's very intriguing how people considered legally blind still have some knowledge of their surroundings! I guess I never took into account that even though damage to the primary visual cortex would prevent people from seeing, the information could find its way to the appropriate place through another pathway.

It is really amazing that the brain can work like that. I find the idea of "alternative pathways" a bit confusing though.
A question that I have is whether this occurs for all blind people, or just a select few?

I too sometimes wonder how the blind are still able to "see." It's very interesting how the man was able to navigate around the objects despite being blind. I even sometimes try to navigate around my house with my eyes shut, but it's impossible!

This is crazy! I think is is so strange that blind people can almost " sense" other people, or in this case objects,around them. I think it really interesting how blind people pay special attention to their other senses. They replace their lack of vision with listening carefully, and feeling. They had extremely sensitive and keen ears, and their sense of touch is very sensitive to different textures. I defiantly take my sense of vision for granted, and I cant imagine not being able to see! Crazy stuff, and I love this post.

I find this blog ineresting. In my personal life, I know when I close my eyes or are not paying attention to something I can "feel" or "sense" when something is coming at me. This article helps explain it in a simple manner. It always surprises me the increases in a one part of your brain when you damage a different part. What I question about this experience is if the guy was tested by the same path or if they changed it everytime or if he just did it once. There could be the chance he memorized the course.

This blog post was very interesting! I too sometimes question whether the blind can see or are they just comfortable with their surroundings enough that they can sense things. I have a friend who is blind and everything we go on the bus together, she walks straight into the opening of the door, as a person who can see would do and I am amaze because I know for a fact she is blind but how is it that she never runs into bus?

I find this amazing and makes me wonder if some blind people almost have a sixth sense to still detect where objects are without actually seeing them for sure. On a daily basis I see a blind man on campus and somehow it almost seems like he knows where objects are without actually receiving any sort of assistance. Whatever it may be this is an interesting phenomenon and cool post.

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This page contains a single entry by lyons206 published on February 19, 2012 9:00 PM.

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