Sensation and Perception Sensations: take it in Sensations: take it in Perception: what we do with it Perception: what we do with it

Vision The eye receives light waves and converts energy into neural impulses by a process called Transduction. The eye receives light waves and converts energy into neural impulses by a process called Transduction.

Wavelength = hue Wavelength = hue Amplitude = brightness Amplitude = brightness

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Rods and Cones are the visual receivers Rods: process black and white. Rods: process black and white. –denser on the outside, active in dim light, Cones: processes color Cones: processes color –clustered mainly in the center of the eye’s focus, the fovea –Needs bright light to function –turns off in dim light –processes with more sharpness than rods.

Color vision Young-Helmholtz Trichromatic Theory : there are three types of cones each sensitive to the primary colors (red, blue, green). Young-Helmholtz Trichromatic Theory : there are three types of cones each sensitive to the primary colors (red, blue, green). –The brain mixes the sensations from those to create all the perceived colors we see. Color blindness: people lack receptors for one of the three.

Two theories within a theory – do we add or subtract? Depends on the situation Coloring book – additive Coloring book – additive Theater lighting - subtractive Theater lighting - subtractive

Problems If the lens or cornea is distorted in relation to the eye then it effects the acuity or sharpness of the image seen. If the lens or cornea is distorted in relation to the eye then it effects the acuity or sharpness of the image seen. One is said to be either nearsighted or farsighted when this occurs. One is said to be either nearsighted or farsighted when this occurs.

The Process Light energy hits the rod or cone which creates a photochemical reaction Light energy hits the rod or cone which creates a photochemical reaction Photochemical reaction creates an electrical impulse sent to bipolar cells, which funnel the electricity to ganglion cells Photochemical reaction creates an electrical impulse sent to bipolar cells, which funnel the electricity to ganglion cells Ganglion cells, whose combined axons create the Optic Nerve, Ganglion cells, whose combined axons create the Optic Nerve, which leads to the brain. The spot where the Optic nerve leaves the eye is a blind spot. which leads to the brain. The spot where the Optic nerve leaves the eye is a blind spot.

Color Vision Opponent process theory : states that some neurons receive one color and are turned off by another. Opponent process theory : states that some neurons receive one color and are turned off by another. –For instance, a neuron can detect red, but another is turned off by it, so you can’t see shades of certain combinations reddish green. This theory is used to explain afterimages, where you wear out the response in one neuron for one color and then can only see the opposing color when staring at a white board, until the neuron replenishes.

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Visual Processing Feature detectors : Separate neurons and neural networks in the brain which are sensitive to specific stimuli, angles, lines, edges, shapes or movements Feature detectors : Separate neurons and neural networks in the brain which are sensitive to specific stimuli, angles, lines, edges, shapes or movements –allowing the brain to differentiate individual objects or movements to concentrate on.

Where feature detectors detect.