PYSC 101 1st EditionExam # 2 Study Guide Lecture 6-8Lecture 6 (January 28)Module 8: Sensing the World Around UsDetermine 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 sawStimulus – energy that produces a response in a sense organPsychophysics – 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 detectedo Stimulus intensity that is detected 50% of the timeo 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 canfirst 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 occurredo Just noticeable difference: the minimum change in stimulation required to detect the difference between two stimulio 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 yogain 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 andconesOrder 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 lighto Turn on in darko Sensitive to light, not coloro Function well in low illuminationo 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 sensitiveo Respond to coloro Operate best in high illuminationo Concentrated in fovea o Adapt quickly in dark room- Fovea: focuses in on a word/picture/something colorfulHow 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 hemisphereFeature Detection- Perception that occurs in visual cortex and have detection cells that direct size/shape/colorTheories 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 wavelengthso Blue-violet colorso Green colorso Yellowed-red colorso DOES NOT explain after-imageso Proposed by Thomas Young - Opponent-process theory: theory that receptor cells for color are linked in pairs, working in opposition of each othero Blue-yellowo Red-greeno Black-whiteo EXPLAINS after-imageso Proposed by Ewald HerinLecture 7 (January 30)Module 10: Hearing and Other SensesWhat 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 musicStructural parts of the Ear- Outer ear: detects direction of sound- Eardrum: vibrates in response to sound- Middle ear: amplifies soundo 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 cellsBasic physical properties of sound- Frequency: the number of wave cycles that occur in a second perceived as pitcho Low frequency (low pitch) has fewer peaks per second than high (higher pitch) frequency- Amplitude: loudness of soundo 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 soundSemicircular 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 sicknessSensory Mechanism of Smell- Olfaction: only sense that goes to the brain and cerebral cortex without stopping at thalamus o