Sensation- is the raw data/input/stimuli.
Perception- how you interpret/feel the data.
Sensation is the process by which we receive information from the environment. You have a specific organ of transduction. It is not the same as the organ of sensation. The organ of sensation in vision is the eye, which "pulls in" photons. Transduction is when those photons are converted into an impulse. The retina is the organ of transduction, it turns photons into a nerve impulse that gets sent to your brain. What's the organ of sensation --> the eye. The organ of transduction is the retina.
Receptors- take a stimulis and transform into a neural signal. Goes to the thalamus and then goes to the section of the brain used to process the right information. So, when we say "I feel cold," am I expressing sensation or perception? Perception. The thing about perception is that it is very/highly selective. You're getting so much information right now from your sense organs, they are giving you more information than you can manage, and so immediately information is labeled either important or unimportant and that stuff gets to your brain. Important information might be the light-waves off the board. Unimportant information might be the woman down the hall (and some of you don't even perceive this). You're only getting 30% of all information that you get, maybe. Once you get that information routed to the whatever processing point in the brain (sound -> temporal lobe), then the temporal lobe is routing the information, to Wernicke's area, then to higher order area- the prefrontal cortex, and then to the hippocampus if you want to do long-term thinking, in a matter of milliseconds.
Top-down v. bottom up. Bottom-up is what babies do. They take all the pieces, and build the piece to a conclusion, so for a little picture of a candy bar, they will start with the lines, the wrapper, the colors, and the word shapes, etc., and then that all gets processed upwards. Top-down is where you start with the candy-bar idea, and then show why you can figure that out, with some confirmation going on there. Bottom-up: you lead to the conclusion. Top-down: you start with the conclusion. In top-down processing, it usually includes what you like / dislike and lots of abstract concepts.
Bottom-up is more elementary. Top-down is more complex.
Transduction- the conversion from whatever energy/stimuli to a nerve impulse. That impulse is sent to the thalamus and routed out to the other brain structures.
Sensory adaptation - is when the stimuli are no longer consciously perceived. For example, you put your socks on in the morning and within minutes you don't consciously feel them. People do this all the time and don't even realize it. It's just getting used to something, like your underwear. You probably don't feel your underwear all day long, and if you do then you need new underwear, but if you don't, then you've "adapted" to it, and you don't consider the constant input to be important, so you set it aside. You just don't feel this stuff all the time, once you acknowledged that it's there. Cologne is an example, at first the person smells it, and then they stop smelling it. Sometimes people add more because they think the smell is no longer there. Adaptation is when you've decided that a particular set of input is no longer important to really focus on. That happens often. Puckett has a friend that lives near a railroad track, and they hear the trains all the time, and they don't hear it at all, but if you go over there, you hear it easily, but they've adapted.
My Eyes Are Deceiving Me
Optical illusions are when your brain fills in the gaps for you, whether or not it is supposed to. When we're reading a book, the ground is the white page, and the figure is the letters on the white page, and so what's black is the figure, and this particular picture, and the most important information is actually the white-space and not the black-space.
You do not see what you think you see. Your eye sees 60 frames per second (what happened to 30 fps??). You are not seeing a continuous stream of information without breaks. Your brain takes the still snapshots and reconstructs what must happen between the snapshots. You guess your gaps- that's what your vision is about. You don't see what's out there. You see what's probably out there. You also have a blind spot in your eye, a section of your retina that has nothing. This tells you some disturbing stuff about your eye. Your eye is always in constant motion, it's trying to make up for the blind spot. It's like trying to put a spot on the lense of the projector in the front of the room. You build the image based on moving your retina around and so on.
The anatomy of the eye
Sclera- outer layer, protection, gelatinous, tough.
Cornea- outer transparent coating in front of the eye. Lets the light into the eye. It's like the glass of a window. The point of having glass is to let light in, but not birds/cockroaches/june-bugs/etc. The cornea keeps the world out, but light in. This is also what we do with lasic surgery.
Lens- transparent tissue that focuses the image by changing shape. This is refractive.
Accomodation is where there is the thickening near, and the thinning distant.
Iris- it's a muscle. That blue or brown or green in your eye is actually a muscle. It is used to make sure that the amount of light going through the pupil (the hole) is the right amount. Your iris is going to relax in this class room because of the lack of light (due to the presentation). When it's dilated, more light can come in. The iris is the color. Just behind the iris is the plastic, flattened, spongy ball, and that's the lense, which is held in place. The muscles stretch or contract the lense, to cause the light going through to change direction, and this helps focusing. There's a space between the cornea and the lense. The iris is between the cornea and the lense, and this space is filled with aqueous humor- it's more liquid than gel. Behind the lense, to the lense to the retina, is a thick jelly called vitrious humor (hard jello, sort of ). The very back of the eye is the retina, which is the organ of transduction where photons are converted to impulse.
Accomodation- changing the shape of the lens to focus. When the lens is stretched, you see farther. You can feel the muscles making your lens change.
Dark absorbs, nondark reflects.
Rods- black&white, night vision, they are not found in the fovea.
Cones- color vision, located in the fovea.
Pupil- round opening in the center of the eye (light enters eye).
No rods and cones in the blind spot, which is where the optic nerve exits your eye. The retina is the organ of vision transduction. The retina is an organ.
Electromicrograph
Optic disc (blind spot)- entry point to the optic nerve.
Fovea - most cones and focal point
Macula- area surrounding fovea, good combination of rods & cones.
The peripheral, all out from the retina, is all rods.
The retina is built 'backwards'- photons go to the very back of the retina, and then bounce into the massive rods and cones in the front of the retina. The way that this is set up is that there is a system of neurons that hand off the information, via the ganglion and bipolar cells, and they all send information to the tangles of nerve fibers, which are all over the back of the retina, which are then bound into the optic nerve, and then it is sent out of the eye. It's very intricate. In the distance of this image you can see some of the cones sticking up ... they are like the topper of a christmas tree. The retina is very complex.
Your eye is not actually a perfect circle. It's wonky, a little bit off. It has a bit of a bump in the circle, at the front. This bump is your cornea.
Stigmatism- when the eye bends the light, there's two main beams of the light. Your eye shape is the same in this case. You can be near-sighted and have a stigmatism. Near-sighted is a bad eye shape, and then stigmatism is a bad diffused beam. Over time, the shape of your eye does change.
Prosbeoptia