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Chapter 3

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Miami University
PSY 111

Sensation and Perception Sequence: sensation, transduction, perception Sensation—activation of the receptors by stimuli in the environment.  Mueller’s Law of Specific Nerve Energies—Each receptor is designed to receive certain types of stimuli. But, under certain circumstances, receptors can receive other types of stimuli (touch stimulates eyes). Perception—(based on learning and expectations) how we interpret information. Process of organizing and making sense of sensory information. Transduction—taking stimulus and putting it in a form that can travel to the brain. Adaptation—reduced sensitivity of the receptors. If the outside environment is not changing, sensory receptors don’t continue to send as much information. (ex. Perfume--You notice it; they don’t. Food—better at first. Living near a sewage treatment plant. Dive right in. Ring. Glasses) Habituation—similar to adaption. But, Habituation occurs in the brain, and adaption occurs in the receptors. (Elevated train doesn’t wake you, but baby’s cry does. Lack of elevated train noise could wake you) Psychophysicist—study the relationship between the mind and the body. Physicist Limen—threshold  Absolute threshold—smallest amount of stimulation that we can register 50% of the time. o Vision: a candle flame at 30 miles on a clear, dark night o Audition: tick of a watch at 20 feet in a quiet room o Olfaction: 1 drop of perfume diffused throughout a 3-room apartment o Gustation—One teaspoon of sugar in two gallons of water o Touch—the wing of a bee falling on your cheek from 1 cm.  Just notable difference—the amount you must add before a change can be detected o Psycophysics—sometimes, we can change the physics but the human brain can’t detect it (volume increase) o Weber's law: ΔI/I = K (where I is intensity and K is Weber’s K)  Ex. For brightness, if Weber’s K = 1/60, change from 120 to 121 is undetectable. Change from 120 to 122 is.  Ex. Buying a car, an armani suit, wedding chair covers. After a large cost, a little more cost doesn’t seem that bad.  Signal Detection Theory—Contention that the threshold varies with the nature of the stimulus (signal) and with background stimulation (noise).  Receiver Operating Characteristics—Likelihood of false negatives and false positives?  Supraliminal Vs. Sub ` liminal Stimuli o Supraliminal is above absolute threshold. Subliminal is below, so you don’t notice you are receiving the stimuli. o Subliminal messaging is attempted often.  James Vickary (1950s New Jersey) insert ―buy coke‖ ―eat popcorn‖ statements into film. Reported ―eat popcorn‖—popcorn sales increased 58%, coke sales increased 18%. However, he made this story up to draw attention to his theatre.  Satanic messages in music. Play song backwards. rd Jabberwocky and the 23 psalm.  Subliminal Self Help Tapes—change a bad behavior o Greenwald Research  Double blind (researchers who have contact with the subject don’t know what tape the subject is given and neither do subjects)  Motivated participants (paid)  Pre and Post measures  Two tapes: improving memory and increasing self esteem  Subject given memory and self-esteem pre-test.  Listen to tape once a day for a month (hear ocean and subliminal message. Some are given tape they want some are given opposite)  Post-test.  Tapes had no effect on memory or self-esteem; didn’t matter if they had correct tape or other tape  They believed that they had improved  Illusory Placebo—they believed that it worked even when there wasn’t even a real placebo effect. o Priming—might push you in a particular direction  Research  Subjects: Psychology graduate students  Task: Generate research ideas  IV: ―shown‖ a smiling face of a familiar colleague or scowling face of faculty supervisor  DV: Lower rating of own ideas if exposed to scowling face  Research—Verbal behavior  Task: Complete GUI_ _  Likely responses: guide or guile  Subliminal priming can affect outcomes  Subliminally shown ―Direct lead escort‖ Outcome is more likely ―Guide‖  Subliminally shown ―deceit treachery duplicity‖ Outcome is more likely ―Guile‖ The Senses  Most people would least like to lose vision. This is the brain’s answer. More of the brain is devoted to vision than any other sense Vision  The Adequate Stimulus (per Mueller’s law): Electromagnetic energy o Waves range from long (radio) to short (gamma). o Visible Spectrum (Roygbiv)–detectable by the human eye.  Length measured in nanometers. Between 380 and 760 nm. Determines Hue/color. Red=longest, Violet=shortest  Amplitude determines intensity/brightness  Saturation determines purity. o Radiant light—visible light is emitted directly by an object (few sources of radiant light. Includes sun and light bulbs) o Reflected light—light reflected by objects o If an object absorbs all light waves, it appears black. If it reflects all light waves, it appears white o If an object reflects only one wavelength, you perceive pure color. Degree of purity decreases as the number of wavelengths reflected increases. o Weber’s K (just noticeable difference) = 1/60 for brightness o Anatomy of the eye  Cornea  pupil  lens  retina  Iris—colored section. Basically a muscle. Can contract or dilate pupil to let in more/less light.  Pupil—opening in eye.  Primary Purpose: Lets light in/adjusts amount of light let in.  Secondary Purpose: Indicator of interest (Research by Hess showing male college students playboy centerfolds). Dilates to show interest.  Retina—light-sensitive tissue at the back of the eye. Contains rods and cones.  Rods—receptors for black and white. ~100 million. Lower threshold (so less light is required to activate them). Lower acuity (sharpness of perception)  Cones—receptors for color. ~5 million. Higher threshold. Higher acuity.  When light strikes rods or cones it causes a chemical reaction, hyperpolarizes rods and cones, and diminishes their inhibitory influence on the bipolar cells  Fovea—point in the middle of the retina that contains the greatest number of cones. (Look straight ahead to see color because center of eye (fovea) contains most cones. Peripheral vision is more black and white)  Color vision o Relatively rare in mammals. Some lower animals see color (Primates, fish, birds, reptiles) o Trichromatic theory—explains color processing in the cones.  Trichromats see all colors in visibile spectrum (because it takes 3 types of cones to se all colors).  There are 3 different cones that are each most sensitive to one of the primary colors. Primary colors or red, blue, green?  Dichromats have 2 working kinds of cones (has difficulty distinguishing between 2 colors). Color- deficient  Monochromats see no color. (either don’t have other types of cones or cones don’t work) Actually color blind. o Opponent-process theory—explains color processing in bipolar cells, thalamus, and cortex. Stresses that activation on one process inhibits another (like red and green). o Color afterimage—perception of color that is not really present. Occurs after viewing a complementary color. o Color Vision Deficiency vs. Color Blindness  Assessment: Ishihara Test for Color Blindness (misnomer, because it tests Color Vision Deficiency)  Color Blindness: Achromatopsia  Causes of Color Deficiency: Diabetes, Glaucoma, Alzheimer’s, Parkinson’s, Multiple Sclerosis, medications (high blood pressure, infections, psychological disorders), aging, chemical exposure (fertilizer, styrene)  May not know they are color deficient.  Color Deficiency: 8% in males, .5% in females (often females are carriers)  Most common form of CD is Red-Green (has trouble telling difference between Red and Green)  Less Common: Blue-Yellow  Difficulties: weather maps, traffic lights, clothing, cooking (raw vs. well done, green tomatoes vs. red tomatoes, ketchup vs. chocolate syrup) Audition (Hearing)  Adequate Stimulus: Vibrating molecule o Frequency measured in Hertz: pitch (inversely correlated to wavelength). o Timbre (purity) o Amplitude measured in decibels (50 is normal conversation) Every time db goes up by 10, it doubles. Measures intensity o Receptors: hair cells located in inner ear o We hear sounds between 20 and 20,000 Hz.  Hearing is most accurate ~1,000 Hz. Greater intensities are required to hear sounds on either end of the spectrum.  Absolute threshold: ticking of a watch at 20 feet  Weber’s K is 1/10 for loudness  Locating Sound: o time delay (occurs when
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