PSY 12000 1st Edition Lecture 6Outline of Last LectureI. Sensation a. Bottom-up Processing b. Top-down Processing c. Examples II. Purpose of Sensing Things a. Adaptation III. Perception of Sensory Stimuli a. Attention IV. Perceptiona. Sensory Adaptation b. Myths of Perception c. Visual Illusions Outline of Current LectureI. Vision a. Theory b. Principles c. Perceiving Motion d. Perceiving Constancy II. Hearing a. Perception of Sound b. Anatomy of the Ear c. Theory d. Auditory Processing e. Vocalizing Sound III. Other Senses a. Skin b. Chemical c. OthersCurrent LectureI. Vision d. Theory -Trichromatic Theory- Three types of cones sensitive to different but notoverlapping ranges of length -Hering’s opponent process theory (red-green and blue-yellow cones) i. After images- sensations that remain after stimulus at one stage of processing the trichromatic theory works then atanother the opponent process takes over ii. Color Blindness 1. Trichromats- people with normal color vision 2. Dichromats- people deficient in the blue-yellow system theredgreen system or both 3. Monochromats- only see black and white and gray iii. Contour-location at which sudden change of brightness occurs iv. Figure-ground- tendency to organize stimuli into a central or foregroundfigure and a background v. Gestalt psychology 1. school of thought interested in how people naturally organizeperception 2. Gestalt principles of perceptual organization-organizingseparate parts of our perceptual field into a unified andmeaningful whole c. Principles 1. Similarity 2. proximity 3. closure 4. continuity a. Shape constancy-recognize things from different angles b. brightness constancy- recognize things in different lights c. size constancy- recognize things are the same even though theyappear to change size at different distances d. Perceiving depth-ability to perceive objects 3 dimensionally e. Binocular cues- combined images from two eyes i. Disparity each eye sees a different image ii. convergence produced by feedback from the muscles thatturn your eyes inward to see a close object iii. Monocular cues available from image in one eye5. Patterns of light and shadow- used by artists to create depth on 2dimages 6. Linear perspective- perception that parallel lines converge 7. Interposition-objects close to us cut off 8. Texture- is finer at far distances 9. Clarity- we see things closer more clearly 10. Relative size- depending on their distance objects are different sizes 11. Motion parallax- nearby objects move faster than faraway ones d. Perceiving motion 1. Retinas cannot detect movement so there are neurons specialized to detect movement which collect feedback from body. The environment provides cues for the neurons. 2. real movement- when an object actually moves 3. apparent movement- • perception of stationary object as moving • makes you feel like you are moving e. Perceiving constancy 1. recognition that objects are constant even though sensory input ischanging 2. constancy-same size despite retinal image changes 3. shape constancy – object is the same shape despite orientation 4. color constancy- object is the same color despite lightdifferences II. Hearing a. Perception of Sound Vibrations in air processed are by auditory systemo Wavelength-frequency-pitch(note)o Amplitude-pressure-loudness(volume)o Complexity-saturation-timbre(quality of the sound)b. Anatomy of the Ear i. Outer Ear 1. Collecting and channeling sound 2. Contains • Pinna • External auditory canal ii. Middle Ear 1. Channels to inner ear through vibrations2. Contains a. Eardrum b. Hammer, anvil, stirrup iii. Inner Ear 1. Converts sound into neural impulses then sent to brain forinterpretation 2. Contains a. Oval window b. cochlea o hair cells (damaged hair cells causes impairedhearing o Auditory nerve (sends info to brain) o basilar membrane (made of hair cells) lines inner wall ofcochlea c. Theory • Place theory- Each frequency produces vibrations along thebasilar membrane • Frequency theory- Perception of frequency depends on howoften auditory nerves fire • Both theories work in their own way and are accurate to adegree • Volley principle- o modification of frequency theory o cluster of nerve cells can fire neural impulses in rapid successiond. Auditory processing- Vibrations go to the Inner ear to the auditory nerve to the Temporal lobe i. Most fibers cross over midline between hemispheres but there aresome fibers that go directly to the same side of hemispheres e. Vocalizing sound i. Each ear receives somewhat different stimuli 1. Distance affects the timing of the sound 2. Sound shadow affects the intensity III. Other Senses a. Skin o touch -mechanical energy or pressure against skin -temperature warm and cold sensory nerve endings orthermoreceptors o pain-Widely dispersed receptors with much higher threshold fordifferent types of physical stimuli(e.g. pressure and heat)
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