PSY1101_Lecture7_Jan30and31_COMPLETE - Chapter 6 Sensation...

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Unformatted text preview: Chapter 6: Sensation and Perception Chapter 6: Sensation and Perception Last Chapter 1) Information Transfer 2) Information Regions Neurons, action potential E.g., visual cortex, association cortex This Chapter 1) Information Detection Sense organs, feature detection Sensation 2) Information Processing Organization and interpretation Perception Video #1 Video #1 The Stimulus Input Vision Vision Light Electromagnetic radiation Packets of energy given off by all things, particularly things that are high in energy (e.g., the sun) Different kinds of electromagnetic radiation For example, X­rays, ultraviolet radiation, infrared radiation, microwaves, radio waves, light Electromagnetic Radiation Wavelength Electromagnetic Radiation Wavelength Packets of electromagnetic radiation oscillate Degree of oscillation determines the wavelength The more the oscillation, the shorter the wavelength The wavelength determines whether or not our eyes can detect it Wavelength and Amplitude Wavelength and Amplitude Wavelength of light determines the hue that we will experience Hue = colour Amplitude of the wavelength determines the brightness of the colour Higher amplitude, brighter colour Lower amplitude, duller colour The Eye The Eye Detect and transduce electromagnetic radiation (light) Transduction is conversion of one form of energy into another Cornea Pupil Iris Lens Retina The Retina The Retina Several layers of cells Photoreceptors Rods and cones Bipolar cells Ganglion cells Axons form the optic nerve Rods and Cones Rods and Cones 120 million rods and 6 million cones Cones mostly in centre of retina (fovea) Better ratio of connections to ganglion cells Only cones are sensitive to colour Rods mostly in periphery Cones more sensitive to detail Only one million ganglion cells Only absorb particular wavelengths of light Rods more sensitive overall Need less light to activate them Blind Spot Blind Spot Axons from the ganglion cells converge and leave the eye in the middle of the retina, near the fovea There is a hole in your retina where there are no receptor cells brain has no direct information about a small area of your visual field but it has indirect information The other eye Eye movements Your brain fills in the information by making its best guess based on the adjacent areas of the retina Feature Detection Feature Detection Optic nerve carries information to the visual cortex Feature detection cells for each area of visual field edges, lines, angles, movements, colors, depth Parallel processing Thalamus Areas of the visual field have corresponding areas of the visual cortex Features extracted simultaneously Supercell clusters in association cortex Respond to complex patterns constructed from individual features Video #2 Video #2 v=RuNDkcbq8PY&feature=related Visual Information Processing Visual Information Processing Colour Vision Colour Vision Young­Helmholtz Trichromatic Theory Any colour created by combining light waves of three primary colours Red, green, blue Theory was that brain worked the same way Hypothesized that retina will have three different types of colour sensitive cells With light waves, not paint Colour Vision Colour Vision Colour blindness Missing red, green, or both red & green cones Red and green look the same Problems with trichromatic theory 1) Missing cones but perceiving yellow 2) Yellow seems pure Colour Vision Colour Vision Afterimages­Lab/colourperceptionweb/theories­Lab/colourperceptionweb/theorie Red and green are opponent colours Blue and yellow are opponent colours (Black and white also) Opponent Process Theory Opposing retinal processes enable colour vision E.g., some cells stimulated by green, inhibited by red Others stimulated by red, inhibited by green ...
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This note was uploaded on 03/02/2012 for the course PSY 1101 taught by Professor Textbook during the Winter '08 term at University of Ottawa.

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