Copyright © Allyn and Bacon 2007 Chapter 4 Sensation & Perception This multimedia product and its contents are protected under copyright law. The following.

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<ul><li>Slide 1</li></ul> <p>Copyright Allyn and Bacon 2007 Chapter 4 Sensation &amp; Perception This multimedia product and its contents are protected under copyright law. The following are prohibited by law: Any public performance or display, including transmission of any image over a network; Preparation of any derivative work, including the extraction, in whole or in part, of any images Any rental, lease or lending of the program. ISBN: 0-131-73180-7 Slide 2 Copyright Allyn and Bacon 2006 Sensation and Perception Sensation An early stage of perception in which neurons in a receptor create an internal pattern of nerve impulses that represent the conditions that stimulated it either inside or outside the body Perception A process that makes sensory patterns meaningful and more elaborate Slide 3 Copyright Allyn and Bacon 2006 The brain senses the world indirectly because the sense organs convert stimulation into the language of the nervous system: neural impulses How Does Stimulation Become Sensation? Slide 4 Copyright Allyn and Bacon 2006 Transduction Transduction Transformation of one form of energy into another especially the transformation of stimulus information into nerve impulses Receptors Specialized neurons that are activated by stimulation and transduce (convert) it into a nerve impulse Slide 5 Copyright Allyn and Bacon 2006 Transduction Sensory pathway Bundles of neurons that carry information from the sense organs to the brain Slide 6 Copyright Allyn and Bacon 2006 Sensory Adaptation Sensory adaptation Loss of responsiveness in receptor cells after stimulation has remained unchanged for a while Slide 7 Copyright Allyn and Bacon 2006 Thresholds Absolute threshold Amount of stimulation necessary for a stimulus to be detected Difference threshold Smallest amount by which a stimulus can be changed and the difference be detected (also called just noticeable difference JND) Slide 8 Copyright Allyn and Bacon 2006 Thresholds Webers law The JND is always large when the stimulus intensity is high, and small when the stimulus intensity is low Fechners law S = k log R S = sensation R = stimulus k = constant that differs for each sensory modality Slide 9 Copyright Allyn and Bacon 2006 Thresholds Stevens power law S = kl a S = sensation k = constant l = stimulus intensity a = a power exponent that depends on the sense being measured Slide 10 Copyright Allyn and Bacon 2006 Signal Detection Theory Signal detection theory Perceptual judgment as combination of sensation and decision-making processes Stimulus event Neural activity Comparison with personal standard Action (or no action) Slide 11 Copyright Allyn and Bacon 2006 Subliminal Persuasion Studies have found that subliminal words flashed briefly on a screen can prime a persons later responses No controlled research has ever shown that subliminal messages delivered to a mass audience can influence peoples buying habits Slide 12 Copyright Allyn and Bacon 2006 The senses all operate in much the same way, but each extracts different information and sends it to its own specialized processing region in the brain How Are the Senses Alike? How Are They Different? Slide 13 Copyright Allyn and Bacon 2006 The Anatomy of Visual Sensation Fovea Area of sharpest vision in the retina Retina Light-sensitive layer at the back of the eyeball Photoreceptors Light-sensitive cells in the retina that convert light energy to neural impulses Rods Sensitive to dim light but not colors Cones Sensitive to colors but not dim light Slide 14 Copyright Allyn and Bacon 2006 The Anatomy of Visual Sensation Optic nerve Bundle of neurons that carries visual information from the retina to the brain Blind spot Point where the optic nerve exits the eye and where there are no photoreceptors Slide 15 Copyright Allyn and Bacon 2006 Color Psychological sensation derived from the wavelength of visible light color, itself, is not a property of the external world The Anatomy of Visual Sensation Visual cortex Part of the brain the occipital cortex where visual sensations are processed Slide 16 Copyright Allyn and Bacon 2006 Transduction of Light in the Retina Slide 17 Copyright Allyn and Bacon 2006 Afterimages Afterimages Sensations that linger after the stimulus is removed In the following slide, fix your eyes on the dot in the center of the flag Slide 18 Copyright Allyn and Bacon 2006 Slide 19 Slide 20 Neural Pathways in the Human Visual System Slide 21 Copyright Allyn and Bacon 2006 How the Visual System Creates Color Electromagnetic spectrum Entire range of electromagnetic energy, including radio waves, X-rays, microwaves, and visible light Visible spectrum Tiny part of the electromagnetic spectrum to which our eyes are sensitive Slide 22 Copyright Allyn and Bacon 2006 Brightness Sensation caused by the intensity of light waves How the Visual System Creates Color Color blindness Vision disorder that prevents an individual from discriminating certain colors Slide 23 Copyright Allyn and Bacon 2006 Color Blindness Slide 24 Copyright Allyn and Bacon 2006 How the Visual System Creates Brightness Wavelength Color Intensity (amplitude) Brightness Slide 25 Copyright Allyn and Bacon 2006 Hearing: If a Tree Falls in the Forest... The Physics of Sound Frequency Number of cycles completed by a wave in a given amount of time Low Frequency High Frequency Slide 26 Copyright Allyn and Bacon 2006 Hearing: If a Tree Falls in the Forest... The Physics of Sound High Amplitude Low Amplitude Amplitude Physical strength of a wave Slide 27 Copyright Allyn and Bacon 2006 How Sound Waves Become Auditory Sensations Tympanic membrane The eardrum Slide 28 Copyright Allyn and Bacon 2006 How Sound Waves Become Auditory Sensations Cochlea Where sound waves are transduced Slide 29 Copyright Allyn and Bacon 2006 How Sound Waves Become Auditory Sensations Basilar membrane Thin strip of tissue sensitive to vibrations Cochlea Slide 30 Copyright Allyn and Bacon 2006 How Sound Waves Become Auditory Sensations Auditory nerve Neural pathway connecting the ear and the brain Slide 31 Copyright Allyn and Bacon 2006 How Sound Waves Become Auditory Sensations Auditory cortex Portion of the temporal lobe that processes sounds Slide 32 Copyright Allyn and Bacon 2006 The Psychology of Pitch, Loudness, and Timbre Pitch Sensory characteristic of sound produced by the frequency of the sound wave Loudness Sensory characteristic of sound produced by the amplitude (intensity) of the sound wave Timbre Quality of a sound wave that derives from the waves complexity Slide 33 Copyright Allyn and Bacon 2006 Deafness Conduction deafness An inability to hear resulting from damage to structures of the middle or inner ear Nerve deafness An inability to hear, linked to a deficit in the bodys ability to transmit impulses from the cochlea to the brain, usually involving the auditory nerve or higher auditory processing centers Slide 34 Copyright Allyn and Bacon 2006 Position and Movement Vestibular sense Sense of body orientation with respect to gravity Kinesthetic sense Sense of body position and movement of body parts relative to each other Slide 35 Copyright Allyn and Bacon 2006 Smell Olfaction Sense of smell Olfactory bulbs Brain sites of olfactory processing Pheromones Chemical signals released by organisms to communicate with other members of the species Slide 36 Copyright Allyn and Bacon 2006 Smell Slide 37 Taste buds Receptors for taste (primarily on the upper side of the tongue) Taste Gustation The sense of taste Slide 38 Copyright Allyn and Bacon 2006 The Skin Senses Touch Warmth Cold Slide 39 Copyright Allyn and Bacon 2006 Pain Placebos Substances that appear to be drugs but are not Placebo effect A response to a placebo caused by subjects belief that they are taking real drugs Slide 40 Copyright Allyn and Bacon 2006 Perception brings meaning to sensation, so perception produces an interpretation of the external world, not a perfect representation of it What is the Relationship Between Perception and Sensation? Slide 41 Copyright Allyn and Bacon 2006 What is the Relationship Between Perception and Sensation? Percept Meaningful product of a perception Slide 42 Copyright Allyn and Bacon 2006 The Machinery of Perceptual Processing Feature detectors Cells in the cortex that specialize in extracting certain features of a stimulus Binding problem A major unsolved mystery in cognitive psychology, concerning the physical processes used by the brain to combine many aspects of sensation to a single percept Slide 43 Copyright Allyn and Bacon 2006 Bottom-Up and Top-Down Processing Bottom-up processing Analysis that emphasizes characteristics of the stimulus, rather than internal concepts Top-down processing Emphasizes perceiver's expectations, memories, and other cognitive factors Slide 44 Copyright Allyn and Bacon 2006 Perceptual Constancies Perceptual constancy Ability to recognize the same object under different conditions, such as changes in illumination, distance, or location Slide 45 Copyright Allyn and Bacon 2006 Perceptual Ambiguity and Distortion Illusions Demonstrably incorrect experience of a stimulus pattern, shared by others in the same perceptual environment Ambiguous figures Images that are capable of more than one interpretation Slide 46 Copyright Allyn and Bacon 2006 Perceptual Illusions Do you see or ? Slide 47 Copyright Allyn and Bacon 2006 Perceptual Illusions The Herman Grid Do you see small gray squares between the black squares? Slide 48 Copyright Allyn and Bacon 2006 Theoretical Explanations for Perception Learning-based inference View that perception is primarily shaped by learning, rather than innate factors Perceptual set Readiness to detect a particular stimulus in a given context Slide 49 Copyright Allyn and Bacon 2006 Cultural Influences on Perception B A Which box is bigger, A or B? Slide 50 Copyright Allyn and Bacon 2006 The Gestalt Approach Gestalt psychology View that much of perception is shaped by innate factors built into the brain Figure Part of a pattern that commands attention Ground Part of a pattern that does not command attention; the background Slide 51 Copyright Allyn and Bacon 2006 Closure Tendency to fill in gaps in figures and see incomplete figures as complete The Gestalt Approach Subjective contours Boundaries that are perceived but do not appear in the stimulus pattern Slide 52 Copyright Allyn and Bacon 2006 The Gestalt Laws of Perceptual Grouping Similarity Proximity Continuity Common fate Prgnanz Slide 53 Copyright Allyn and Bacon 2006 Law of Prgnanz A BIRD IN THE THE HAND Slide 54 Copyright Allyn and Bacon 2007 End of Chapter 4 </p>

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