Hi everybody. Today we're going to talk about how colors would affects the perception of. The quality of a dish, the taste. Now before we go into it let's look at what we are going to talk about in this section. We're going to understand a little bit about the background about our sensory organ, our eyes. How we will be able to perceive light and color. And we want to understand how this color is being generated. So we're talking about how to light and paint and all of this color fold substance they are going to generate an effect in a lie. And finally we want to understand how this color is going to change the flavor of a popular dish. Now we want to understand how we perceive light. Why, because when we see food usually that's the first contact we have with a particular substance. We see them from afar before they are close enough that we can smell them and before they are close enough that we can put them in our mouth so that we can taste them. So seeing them is very important. And it's comes so fast that usually, it gives us the first perception about the quality. Now, how would we be able to see food? Usually, we use our eyes, and with our eyes, light would come into our eyeball through the lens. Now this important thing that we need to understand is that in fact in our eye there are different layers of tissue and on them in fact we have something called photo receptor. I want to focus on two area, one is that in our eye in fact we do have. An area which we call fovea, which is right at the center of our retina. And on the other position, actually, there's something called a blind spot. In fact, there's no photoreceptor whatsoever. Now, what I want to show you is the following. In fact, on our retina, there are a whole bunch of photoreceptor cell. There are two type. One is more like a rod shape, a rod, and the other one is the cone shape. Very simple terms. For the rod-shaped photoreceptor, they allowed us to detect the intensity of light. So basically, what it allowed us to do is to monitor whether the light is very bright or very dark, and they give you that contrast. The second drop of the photoreceptors is called, cone, and for the cone, in fact, they have pigmented molecule that allows us to visualize color because they would be excited by different kind of wave length, and as a result, we will be able to. Monitor whether some light when they come into our eyes. Whether it's of one particular wavelength or the other. That means they give us the perception of color. Now how are they going to be organized? In fact, on the retina we have multiple layer of cells. So these are the photo receptor cells, the rods and the cones. And in front of them, we have a whole bunch of neurons that helped us to integrate the information. Now, this group of neurons, they're very important and I'm going to cover that a little bit later. But the lights come in from your left into it and they will hit onto these receptor cells. When they were excited what they are going to do? They are going to send out signal. So how are they distributed on the retina? In fact, we find that if you now, you look into your eyeball from the front, and you look onto the retina you will find that this is the position where the fovea is located. In fact, they are very densely populated by all this pigmented cone cells that allows us to perceive color. On the other hand, on the peripheral you see that mostly they are dominated by this cell which is only sensitive to the light intensity. So, this is a distribution of how they are located on both side peripheral port you have a lot of this rods out. But in the center you have a very densely populated cone style. Important part is well, there is a spot, basically they are totally absent. We call them the blind spot, in fact that's the place where our optic nerve go into our eyeball. And if the light fall into that particular area, basically you can perceive light or color. Now so what happened? Is that, when these receptor cells, when they receive the light, the, I think they trigger a whole sequence of response, cellular response. That eventually, like what happened in the smell, like what happened in the taste. These neurons they're going to send out signals, which is electrical signal, which will be processed by this group of inter neurons behind all the sensory cells, and then they would be sent to your brain, and then your brain would be able to tell whether that is a pliga color, or what intensity it is. Now, the interesting thing is that when our eyes photo receptor cell perceive all these signals and they send a signal out, they do not simply send it to one particular spot in a brain. for example, let me look at the right eye in this case. You may find that in fact all this photo receptor cell they would have all this nerve fiber coming out of it. And those on the right side of this eyeball. In facts, they would have their nerves going out and be connected to the right brain. But all the nerves that was coming out from the left side of this eyeball, they would go to the left brain. They cross the mid line. The same thing happens for the left eye too. The one on the left go to the left brain, and the one on the right go to the right brain. And through this information coming from both the left and the right eye, it allows us to perceive the outside world with a stereo vision. Now, so that is basically the organization of our visual system that allows us to perceive what outside world is, color, light intensity, and what exactly they are.
