Lab #3 - Photopigments

Lab #3 - Photopigments

Our next task is to work out how you translate the image formed in the back of a pinhole camera into some kind of signal that your nervous system can work with. We'll start addressing this question by examining photopigments in Lab #3. To complete this lab, you'll need access to some sunprint paper, which is available from a variety of different sources. Here's where I bought mine: http://www.sunprints.org.

You can find the lab documents at the link below:

https://drive.google.com/file/d/17MVZqvyiCRdT_Qu5n_CtK3rVcUP0zoOG/view

When you're done, move on to the Lab #4 post to make a few more observations that will give us a little more information about the retina. Afterwards, we'll try to put all of this together into a more comprehensive description of what's happening at the back of the eye.

Comments

Monocular cues for depth perception

Monocular cues for depth perception In our last post, we discussed how you can use the information from your two eyes to estimate the relative depth of objects in the visual field. Both vergence and binocular disparity provided cues to where objects were situated in depth relative some fixation point, allowing us to obtain some information about the 3D arrangement of objects in space. Clearly, two eyes are helpful in resolving the ambiguity that follows from projecting the light coming from a three-dimensional scene onto a two-dimensional surface. We said that this projection of light onto the retina made it much harder to make good guesses about depth from one image, and that using two images was a necessary step towards making it possible for you to recover this information from the retinal data. However, consider the picture below: Figure 1 - A boid in some trees. Some things here look closer to you than others, but how do you tell that when you don't have bino...

What is Light?

What is light (and what does it do?) To begin talking about vision, we need to talk about light. What I mean is that we need to work out a way of thinking about what light is as a physical stimulus so that we can understand how it interacts with the physiology in our eye and brain. Our goal is to come up with a description of what light is that I’ll be calling a model . A good model allows us to account for some properties of a complex system and predict how it should behave under different circumstances. Good models also frequently leave out some aspects of a complex system in favor of being easier to work with, which means we have to remember that our descriptions of complex systems have limits. For now, we’ll have a limited set of phenomena that we’re trying to understand, but even so we’ll see that we’re leaving out some properties of light that are physically meaningful in some circumstances, but not terribly meaningful given our physiology. What is light?...

Introduction to high-level vision

Introduction to high-level vision With this blog post, we begin to talk about a new and challenging topic in human vision: high-level vision. Before, we go any further, we need to address an important question: How is this different than what we’ve been talking about before? To date, we’ve spent a lot of time talking about some of the basic principles regarding the way your visual system measures the light in your environment. For example, you have photoreceptors that transduce light and provide a signal that carries information about the wavelength of the light you saw. Further on in your visual system, cells in the LGN and V1 measure various patterns of light and send information on about the dots, edges, and lines you may have seen. These kinds of processes that are mostly concerned with making measurements that describe the incoming light are what I’d refer to as low-level vision . Figure 1 - Measuring the wavelength content of a light or the pattern of li...

Seeing and Perceiving

Search This Blog