SciChat #5 Recap: How things see

A recap of SciChat #5 with Avani Gadani follows. Avani talked about our understanding of how our brains get useful information out of what our eyes see, and how computers and robots “see”.

Q: When you hallucinate does it have anything to do with your eyes?

A: You have neurons in your visual system and they’re kind of going off for reasons that we don’t understand.  So the information doesn’t only go from your eye to your brain to the back of your brain that has these ideas, it can go the other way too.  So the idea part of your brain, the hippocampus, where you’re storing all your data, kind of like a giant hard drive in the back of your brain, the hippocampus can send signals forward to the part of your brain that looks at vision and give it hallucinations and dreams that look like you’re seeing something but your eyes aren’t involved.

Q: How does a brain make a picture from all the broken up signals?

A: To be honest with you, we don’t know that yet. We have some guesses. The current guess is that the signals go in and at every level of the brain they get more and more compact and we’re making some order – these two pictures look like they go together so let’s examine them as a single picture and then at the next level down you go down to another picture and so on and so on until we get to the organization of the brain and that’s exactly what we’re trying to figure out right now – how do we get from all those pictures to the idea in the brain.

Q: How do you know that the eye is made up of different parts?

A: Because people have taken them apart.

Q: How we actually know that we’re seeing what we’re seeing?

A: We absolutely don’t.  All we have to work on is that we have some idea that the light is coming into our brain and since we were little babies we’ve been touching things and licking things and smelling things and trying to put all of these senses together  and for all we know it could be completely different in real life but you’re getting into some pretty deep metaphysical questions here because what’s real may not be what we see it as.

Q: Why can some people identify shapes and faces better than others?

A: Remember when we were talking about those cells in your brain that look at the light and see the pictures? Some people don’t end up with these cells that fire on faces, in most people a large portion of our brain, the visual part of our brain is actually keyed specifically on faces, faces are very important. That’s why for example sometimes you might look at a school bell and sort of see two eyes on it, because your brain is trying to find a face anywhere it can. But for some people that never goes on so it’s really hard for them.

Q: Why are some people colorblind?

A: So inside your eye on the back part here you have these things called rods and cones that grab the light that goes on the back of your eye and they turn into signals for your brain. So people who are colorblind are missing some of these cones and so they don’t get all of the wavelengths of light. So color comes from light that is smushed together differently so it makes a wave and red is kind of big and purple is kind of squishy and they don’t have receptors for all these colors.

Q: Why can’t dogs see colors?

A: I don’t think they have these cones, I’m not sure but that would be my guess.