PYSC 101 1st Edition Exam 2 Study Guide Lecture 6 8 Lecture 6 January 28 Module 8 Sensing the World Around Us Determine the difference between sensation perception and stimulus What is psychophysics Methods used to study sensory threshold Sensation the activation of the sense organs by a source of physical energy ex Light visual sensation Perception the sorting out interpretation analysis and integration of stimuli by the sense organs and brain ex Knowing what we saw Stimulus energy that produces a response in a sense organ Psychophysics the study of the relationship between the physical aspects of stimuli and out psychological experience of them Methods used to study sensory threshold Absolute threshold the smallest intensity of a stimulus that must be present for the stimulus to be detected o Stimulus intensity that is detected 50 of the time o Ex Experiment where light is turned off The light is turned on dimmed slowly and you have to tell when you can first read a textbook When you can first see enough to read the textbook this is your absolute threshold Difference Threshold the smallest level of added or reduced stimulation required to sense that a change in stimulation has occurred o Just noticeable difference the minimum change in stimulation required to detect the difference between two stimuli o Weber s Law a basic law of psychophysic s state that a just noticeable difference is a constant proportion to the intensity of an initial stimulus rather than a constant amount Difference Threshold increases magnitude increases Ex two room apartment in 1 room you are study in other room your roommate is listening to soothing music quickly while doing yoga If your roommate increased the volume you d be able to tell easily However if your roommate was having a party instead of doing yoga in her room if she increased the music that was already loud it d be harder to tell o Smallest Adaptation an adjustment in sensory capacity after prolonged exposure to unchanging stimuli Ex you don t register every stimuli like when teachers lecturing you listen to teacher and ignore the people sneezing the desks squeaking and people taking there pencils Module 9 Vision Describe the structural components of the eye What happens when light reaches the eye How do messages get from the eye to the brain What are the two theories of colored vision Structural Components of the Eye Cornea bends light as it passes through o Light first passes through Pupil black part of the eye opening in the middle of iris o Size increases in dark decreases in light Iris colored part of the eye Lens bends light rays so they can be focused to the retina Retina light converted to electrical impulses to go to the brain and contains rods and cones Order light passes through eye Cornea iris lens retina What happens when light reaches the eye Rods thin cylindrical receptor cells in the retina that are highly sensitive to light o Turn on in dark o Sensitive to light not color o Function well in low illumination o Have rhodopsin which undergo chemical changes when energized by light Cones cone shaped light sensitive receptor cells in the retina that are responsible for sharp focus and color perception particularly in bright light o Not light sensitive o Respond to color o Operate best in high illumination o Concentrated in fovea o Adapt quickly in dark room Fovea focuses in on a word picture something colorful How the message gets from the eye to the brain Rods cones bipolar cells ganglion cells optic nerve primary visual cortex Optic nerve a bundle of ganglion axons that carry visual information to the brain Blind spot where the optic nerve leaves the retina Optic chiasm separates left visual field to right hemisphere Feature Detection Perception that occurs in visual cortex and have detection cells that direct size shape color Theories of colored vision Trichromatic Theory theory that there are three kinds of cones in the retina each of which responds primarily to a specific range of wavelengths o Blue violet colors o Green colors o Yellowed red colors o DOES NOT explain after images o Proposed by Thomas Young Opponent process theory theory that receptor cells for color are linked in pairs working in opposition of each other o Blue yellow o Red green o Black white o EXPLAINS after images o Proposed by Ewald Herin Lecture 7 January 30 Module 10 Hearing and Other Senses What is sound Describe the structural parts of the ear Describe the basic physical properties of sound Distinguish between the place theory and frequency theory Explain how semicircular canals detect motion Describe the sensory mechanism of smell Describe the sensory mechanism of taste Describe the skins senses What is the gate control theory What are ways to manage pain Sound movement of air molecules brought about by a source of vibration Right ear responds to speech Left ear responds to music Structural parts of the Ear Outer ear detects direction of sound Eardrum vibrates in response to sound Middle ear amplifies sound o Parts include the hammer anvil and stirrup Inner Ear o Cochlea coiled tube in the ear filled with fluid that vibrates on responds to sound o Movement of fluid within cochlea deforms hair cells of basilar membrane which converts sound waves into neural activity o Basilar membrane vibrating structure that runs through the center of the cochlea dividing it into an upper chamber and lower chamber containing sense receptors for sound Covered with hair cells Basic physical properties of sound Frequency the number of wave cycles that occur in a second perceived as pitch o Low frequency low pitch has fewer peaks per second than high higher pitch frequency Amplitude loudness of sound o Measure in decibels Place Theory different areas of basilar membrane respond to different frequencies Frequency Theory entire basilar membrane acts like a microphone vibrating as a whole in response to a sound Semicircular membranes Definition when head twists fluid moves through canals touching motion sensors that signal rotational or angular movement Helps with balance Otoliths crystals that sense forward backward up down and pull of gravity o Responsible for space sickness Sensory Mechanism of Smell Olfaction only sense that goes to the brain and cerebral cortex without stopping at thalamus o Olfactory cells found throughout nasal cavity Directly connected to olfactory bulb right to amygdala o Pheromones chemicals that effect behavior Sensory Mechanism of Taste