Copyright © Houghton Mifflin Company. All rights reserved. 3–13–1 Chapter Three Sensation and Perception

Copyright © Houghton Mifflin Company. All rights reserved. 3–23–2 Did You Know That… Our sense of smell may not be as keen as that of dogs, but humans can detect the presence of even one drop of perfume dispersed through a small house? Roy G. Biv is one of the most famous names learned by psychology students, but he is not a real person? Listening to music on a “Walkman” or similar device can permanently damage your hearing?

Copyright © Houghton Mifflin Company. All rights reserved. 3–33–3 Did You Know That… (cont.) Salmon use the sense of smell to sniff out the streams of their birth when they return to spawn? Some people are born with a distaste for broccoli? We have a sense that enables us to locate the parts of our body in the dark?

Copyright © Houghton Mifflin Company. All rights reserved. 3–43–4 Did You Know That… (cont.) Newborn babies prefer the sounds of their mothers’ voices to the voices of other women? The mechanism that makes motion pictures possible lies in the viewer, not the projector?

Copyright © Houghton Mifflin Company. All rights reserved. 3–53–5 Module 3.1 Sensing Our World: Basic Concepts of Sensation

Copyright © Houghton Mifflin Company. All rights reserved. 3–63–6 Module 3.1 Preview Questions What is sensation? What is the difference between absolute thresholds and difference thresholds? What factors contribute to signal detection? What is sensory adaptation?

Copyright © Houghton Mifflin Company. All rights reserved. 3–73–7 What Is Sensation? The process by which we receive, transform, and process stimuli from the outside world to create sensory experiences of vision, touch, hearing, taste, smell, etc.

Copyright © Houghton Mifflin Company. All rights reserved. 3–83–8 Sensory Receptors Specialized cells that detect sensory stimuli and convert them into neural impulses. Locations of sensory receptors: –Eyes –Ears –Nose –Mouth –Joints, muscles –Skin

Copyright © Houghton Mifflin Company. All rights reserved. 3–93–9 Psychophysics The study of the relation between the features of physical stimuli and the sensations we experience in response to these stimuli. Gustav Theodor Fechner’ (1860) Elements of Psychophysics

Copyright © Houghton Mifflin Company. All rights reserved. 3–10

Copyright © Houghton Mifflin Company. All rights reserved. 3–11 Absolute and Difference Thresholds Absolute Threshold: Smallest amount of a stimulus that a person can reliably detect. Difference Threshold: Minimal differences between two stimuli that people can reliably detect. –Also called “just-noticeable difference” –Weber’s law

Copyright © Houghton Mifflin Company. All rights reserved. 3–12

Copyright © Houghton Mifflin Company. All rights reserved. 3–13 Signal Detection The theory that the threshold for detecting a signal depends on factors involving: –The intensity of the stimulus, –The level of background stimulation, –The biological and psychological characteristics of the perceiver.

Copyright © Houghton Mifflin Company. All rights reserved. 3–14 Sensory Adaptation The process by which sensory receptors adapt to constant stimuli by becoming less sensitive to them. Adaptation may not occur when repeatedly exposed to certain strong stimuli.

Copyright © Houghton Mifflin Company. All rights reserved. 3–15 Module 3.2 Vision: Seeing the Light

Copyright © Houghton Mifflin Company. All rights reserved. 3–16 Module 3.2 Preview Questions How do the eyes process light? What are feature detectors, and what role do they play in visual processing? What are the two major theories of color vision? What are the two major forms of color blindness?

Copyright © Houghton Mifflin Company. All rights reserved. 3–17 Figure 3.1: The Electromagnetic Spectrum

Copyright © Houghton Mifflin Company. All rights reserved. 3–18 Figure 3.2: The Color Spectrum

Copyright © Houghton Mifflin Company. All rights reserved. 3–19 Figure 3.3: Parts of the Eye

Figure 3.5: Light to Neural Impulses

Copyright © Houghton Mifflin Company. All rights reserved. 3–21 Feature Detectors Neurons that respond to specific features of the visual stimulus. Visual cortex compiles information from various cells to form meaningful patterns.

Copyright © Houghton Mifflin Company. All rights reserved. 3–22 Trichromatic Theory of Color Vision Thomas Young ( ) Hermann von Helmholtz ( ) Eyes have 3 types of color receptors or “cones.” –Red, green, blue-violet

Copyright © Houghton Mifflin Company. All rights reserved. 3–23

Copyright © Houghton Mifflin Company. All rights reserved. 3–24

Copyright © Houghton Mifflin Company. All rights reserved. 3–25 Opponent-Process Theory Ewald Hering ( ) Three pairs of opposing color receptors –Red-Green –Blue-Yellow –Black-White When one color is activated, other is inhibited.

Copyright © Houghton Mifflin Company. All rights reserved. 3–26 Which Theory of Color Vision Is Right? Both theories to a certain extent. Trichromatic theory is correct at receptor level. Opponent-process is correct with respect to behavior of cells that lie between the cones and the occipital lobe.

Copyright © Houghton Mifflin Company. All rights reserved. 3–27 Color Blindness Trichromats: Normal color vision Monochromats: No color vision Dichromats: Can see some colors but not others

Copyright © Houghton Mifflin Company. All rights reserved. 3–28 Module 3.3 Hearing: The Music of Sound

Copyright © Houghton Mifflin Company. All rights reserved. 3–29 Module 3.3 Preview Questions How does the ear enable us to hear sound? What determines our perception of pitch? What are the main types and causes of deafness?

Copyright © Houghton Mifflin Company. All rights reserved. 3–30 Figure 3.10: Sound Waves

Copyright © Houghton Mifflin Company. All rights reserved. 3–31 Characteristics of Sound Amplitude determines perceived loudness. Frequency determines perceived pitch.

Copyright © Houghton Mifflin Company. All rights reserved. 3–32 Figure 3.11: Conversion of Sound Waves into Neural Impulses

Copyright © Houghton Mifflin Company. All rights reserved. 3–33 Perception of Pitch Place Theory: Location of vibration along basilar membrane determines pitch. Frequency Theory: Basilar membrane vibrates at same frequency as sound wave. Volley Principle: Groups of neurons along basilar membrane fire in rotation.

Copyright © Houghton Mifflin Company. All rights reserved. 3–34 Figure 3.12: Sounds and Decibels

Copyright © Houghton Mifflin Company. All rights reserved. 3–35 Hearing Loss Conduction Deafness: Damage to middle ear. –May benefit from hearing aids. Nerve Deafness: Damage to hair cells of the inner ear or auditory nerve. –Use of cochlear implants sometimes successful. Hearing loss largely due to years of abuse from loud music and noise.

Copyright © Houghton Mifflin Company. All rights reserved. 3–36 Module 3.4 Our Other Senses: Chemical, Skin, and Body Senses

Copyright © Houghton Mifflin Company. All rights reserved. 3–37 Module 3.4 Preview Questions How do we sense odors and tastes? What are the skin senses? What are the kinesthetic and vestibular senses?

Copyright © Houghton Mifflin Company. All rights reserved. 3–38 Figure 3.13: Olfaction

Copyright © Houghton Mifflin Company. All rights reserved. 3–39 Olfaction Smell is only sense not to pass through the thalamus. Odor preferences seem to be inborn. Key factor in the flavor of food. Serves many other functions in various animal species.

Copyright © Houghton Mifflin Company. All rights reserved. 3–40 Pheromones Chemical substances emitted by many species. Pheromones play important roles in many behaviors, including sexual attraction. Do pheromones influence human behaviors?

Copyright © Houghton Mifflin Company. All rights reserved. 3–41 Taste Four basic tastes: sweet, sour, salty, bitter Flavor derives from: taste, aroma, texture, temperature

Copyright © Houghton Mifflin Company. All rights reserved. 3–42 Factors Influencing Food Preference Cultural background Genetic factors Taste sensitivity –One in 4 are “supertasters”

Copyright © Houghton Mifflin Company. All rights reserved. 3–43 The Skin Senses Largest sensory organ Codes for sensations of touch, pressure, warmth, cold, and pain

Copyright © Houghton Mifflin Company. All rights reserved. 3–44 Gate-Control Theory Of Pain Mechanism in spinal cord controls pain messages. Bottleneck at the “gate” may block pain. Role of endorphins in controlling pain –May explain benefits of acupuncture.

Copyright © Houghton Mifflin Company. All rights reserved. 3–45 Kinesthesis Body sense that provides information about: –Movement of body parts –Relative position of body parts Receptors in joints, ligaments, muscles

Copyright © Houghton Mifflin Company. All rights reserved. 3–46 Vestibular Sense Functions: –Monitors position of body in space –Helps maintain balance Conflict with vision = motion sickness

Copyright © Houghton Mifflin Company. All rights reserved. 3–47 Figure 3.16: Vestibular Sense (Larger View)

Copyright © Houghton Mifflin Company. All rights reserved. 3–48 Module 3.5 Perceiving Our World: Principles of Perception

Copyright © Houghton Mifflin Company. All rights reserved. 3–49 Module 3.5 Preview Questions What is perception? How is perception influenced by attention and perceptual set? What are the two general modes of processing visual stimuli? What are the Gestalt principles of perceptual organization?

Copyright © Houghton Mifflin Company. All rights reserved. 3–50 Module 3.5 Preview Questions (cont.) What is perceptual constancy, and what cues do we use to perceive depth and movement? What are visual illusions? Does subliminal perception exist? Does evidence support the existence of ESP?

Copyright © Houghton Mifflin Company. All rights reserved. 3–51 Perception Process by which the brain interprets sensations, turning them into meaningful representations of the world It is an active process. Perceptions may not accurately reflect external reality.

Copyright © Houghton Mifflin Company. All rights reserved. 3–52 Figure 3.17: Perception vs. Reality?

Copyright © Houghton Mifflin Company. All rights reserved. 3–53 Attention Selective Attention: Attention is limited to certain stimuli while other stimuli are filtered out. Influenced by: –Motivational states –Repeated exposure Constant exposure can lead to habituation.

Copyright © Houghton Mifflin Company. All rights reserved. 3–54 Perceptual Set Perceptions are influenced by expectations, preconceptions. Is this the Letter B or the Number 13?

Copyright © Houghton Mifflin Company. All rights reserved. 3–55 Figure 3.19: A Duck or a Rabbit? Source: © Figure from H.R.Schiffman, Sensation and Perception: An Integrated Approach, pp.190 & 220. Copyright © John Wiley & Sons Inc. Reprinted with permission.

Copyright © Houghton Mifflin Company. All rights reserved. 3–56 Visual Processing Bottom-Up Processing: Focus on specific shapes, individual features Top-Down Processing: Experience and knowledge shape perception

Copyright © Houghton Mifflin Company. All rights reserved. 3–57 Figure and Ground Perception Reversible FigureAmbiguous Figure

Copyright © Houghton Mifflin Company. All rights reserved. 3–58 Figure 3.23: Old/Young Woman

Copyright © Houghton Mifflin Company. All rights reserved. 3–59 Figure 3.24: Gestalt Laws of Grouping

Copyright © Houghton Mifflin Company. All rights reserved. 3–60 Perceptual Constancies The tendency to perceive an object as remaining the same even when retinal image changes. Examples –Size constancy –Color constancy –Brightness constancy –Shape constancy

Copyright © Houghton Mifflin Company. All rights reserved. 3–61 Figure 3.25: Shape Constancy

Copyright © Houghton Mifflin Company. All rights reserved. 3–62 Binocular Cues for Depth Cues for depth that involve both eyes. Retinal Disparity: Cue for distance based on the slight differences in the visual impressions formed in both eyes. Convergence: Cue for distance based on the degree of tension required to focus two eyes on the same object.

Copyright © Houghton Mifflin Company. All rights reserved. 3–63 Cues for Motion Perception Path of image as it crosses the retina The changing size of the object

Copyright © Houghton Mifflin Company. All rights reserved. 3–64 Figure 3.28: Müller-Lyer Illusion and Ponzo Illusion

Copyright © Houghton Mifflin Company. All rights reserved. 3–65 Figure 3.29: Impossible Figure

Copyright © Houghton Mifflin Company. All rights reserved. 3–66 Figure 3.30: Moon Illusion

Copyright © Houghton Mifflin Company. All rights reserved. 3–67 Figure 3.31: Stroboscopic Movement

Copyright © Houghton Mifflin Company. All rights reserved. 3–68 Phi Phenomenon Illusion of movement created by the rapid switching on and off of columns of lights.

Copyright © Houghton Mifflin Company. All rights reserved. 3–69 Cultural Differences Perception influenced by both our sensory systems as well as our cultural experiences. Müller-Lyer illusion and the carpentered-world hypothesis Ponzo illusion less prominent among people of Guam.

Copyright © Houghton Mifflin Company. All rights reserved. 3–70 Subliminal Perception Stimuli presented below level of conscious awareness. Can it influence attitudes or behavior?

Copyright © Houghton Mifflin Company. All rights reserved. 3–71 Extrasensory Perception Perception that occurs without benefit of the known senses. Common forms of paranormal phenomena: –Telepathy –Clairvoyance –Precognition –Psychokinesis Has not been demonstrated scientifically.

Copyright © Houghton Mifflin Company. All rights reserved. 3–72 Module 3.6 Application: Psychology and Pain Management

Copyright © Houghton Mifflin Company. All rights reserved. 3–73 Module 3.6 Preview Question What have psychologists learned about controlling pain?

Copyright © Houghton Mifflin Company. All rights reserved. 3–74 Pain Management Distraction Creating a bottleneck at the “gate” Changing thoughts and attitudes Obtaining accurate information Meditation Biofeedback