Sensation and Perception

Sensation and Perception
Sensation & Perception 11/17/2018 Sensation and Perception Chapter 6 Prepared by Krista D. Forrest, Ph.D. These slides © 2006 Prentice Hall Psychology Publishing. Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Pearson Education Canada
Chapter Outline Our Sensational Senses Vision Hearing Other Senses Perceptual Powers: origins and influences Puzzles of perception Copyright © 2007 Pearson Education Canada

Defining Sensation and Perception
Sensation & Perception 11/17/2018 Defining Sensation and Perception Sensation The detection of physical energy emitted or reflected by physical objects It occurs when energy in the external environment or the body stimulates receptors in the sense organs Perception The process by which the brain organizes and interprets sensory information Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Sensation & Perception
11/17/2018 Ambiguous Figure Coloured surface can be either the outside front surface or the inside back surface Cannot simultaneously be both Brain can interpret the ambiguous cues two different ways Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

The Riddle of Separate Sensations
Sensation & Perception 11/17/2018 The Riddle of Separate Sensations Sense receptors Specialized cells that convert physical energy in the environment or the body to electrical energy that can be transmitted as nerve impulses to the brain Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Sensation & Perception Processes
11/17/2018 Sensation & Perception Processes Figure 3.Davis 2 from: Kassin, S. (1998). Psychology, second edition. Upper Saddle River, NJ: Prentice Hall. Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Doctrine of Specific Nerve Energies
Sensation & Perception 11/17/2018 Doctrine of Specific Nerve Energies Different sensory modalities exist because signals received by the sense organs stimulate different nerve pathways leading to different areas of the brain Synthesia A condition in which stimulation of one sense also evokes another Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Absolute Sensory Thresholds
Sensation & Perception 11/17/2018 Absolute Sensory Thresholds Vision: A single candle flame from 30 miles on a dark, clear night Hearing: The tick of a watch from 20 feet in total quiet Smell: 1 drop of perfume in a 6-room apartment Touch: The wing of a bee on your cheek, dropped from 1 cm Taste: 1 tsp. Sugar in 2 gal. water Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

11/17/2018 Difference Threshold The smallest difference in stimulation that can be reliably detected by an observer when two stimuli are compared Also called Just Noticeable Difference (JND) Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Signal-Detection Theory
Sensation & Perception 11/17/2018 Signal-Detection Theory A psychophysical theory that divides the detection of a sensory signal into a sensory process and a decision process Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Sensory Adaptation and Deprivation
Sensation & Perception 11/17/2018 Sensory Adaptation and Deprivation Adaptation The reduction or disappearance of sensory responsiveness when stimulation is unchanging or repetitious Prevents us from having to continuously respond to unimportant information Deprivation The absence of normal levels of sensory stimulation Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Sensing without perceiving
Selective attention: The focusing of attention on selected aspects of the environment and the blocking out of others Inattentional blindness: Failure to consciously perceive something you are looking at because you are not attending to it Copyright © 2007 Pearson Education Canada

11/17/2018 What We See Hue Visual experience specified by colour names and related to the wavelength of light Brightness Lightness and luminance; the visual experience related to the amount of light emitted from or reflected by an object Saturation Vividness or purity of colour; the visual experience related to the complexity of light waves Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

11/17/2018 An Eye on the World Cornea Protects eye and bends light toward lens Lens Focuses on objects by changing shape Iris Controls amount of light that gets into eye Pupil Widens or dilates to let in more light Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

An Eye on the World 11/17/2018 Retina: Neural tissue lining the back of the eyeball’s interior containing the receptors for vision Rods: Visual receptors that respond to dim light Cones: Visual receptors involved in colour vision Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

The Structures of the Retina
Sensation & Perception 11/17/2018 The Structures of the Retina Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

The Visual System is not a Camera
Sensation & Perception 11/17/2018 The Visual System is not a Camera Much visual processing is done in the brain Some cortical cells respond to lines in specific orientations (e.g. horizontal) Other cells in the cortex respond to other shapes (e.g., bulls-eyes, spirals, faces) Feature-detectors Cells in the visual cortex that are sensitive to specific features of the environment Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Hubel & Wiesel’s Experiment
Sensation & Perception 11/17/2018 Hubel & Wiesel’s Experiment Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

11/17/2018 How We See Colours Trichromatic theory Opponent process theory Figure 5.04 from Wade, C., & Tavris, C. (2002). Invitation to Psychology, 2nd Ed. Upper Saddle River, NJ: Prentice Hall. Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

11/17/2018 Trichromatic Theory Young (1802) & von Helmholtz (1852) both proposed that the eye detects 3 primary colours red, blue, & green All other colours can be derived by combining these three Figure 3.9 from: Kassin, S. (2001). Psychology, third edition. Upper Saddle River, NJ: Prentice Hall. Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Opponent-Process Theory
Sensation & Perception 11/17/2018 Opponent-Process Theory A competing theory of colour vision, which assumes that the visual system treats pairs of colours as opposing or antagonistic Opponent-Process cells are inhibited by a colour, and have a burst of activity when it is removed Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Test of Colour Deficiency
Sensation & Perception 11/17/2018 Test of Colour Deficiency Figure 3.12 from: Kassin, S. (1998). Psychology, second edition. Upper Saddle River, NJ: Prentice Hall. Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Constructing the Visual World
Sensation & Perception 11/17/2018 Constructing the Visual World Form perception Depth and distance perception Visual constancies: When seeing is believing Visual illusions: When seeing is misleading Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

11/17/2018 Form Perception Gestalt principles describe the brain’s organization of sensory building blocks into meaningful units and patterns Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Examples of Gestalt Principles
Sensation & Perception 11/17/2018 Examples of Gestalt Principles Proximity: Things close to one another are grouped together Closure: The brain tends to fill in gaps to perceive complete forms Figure 3.23 from: Kassin, S. (1998). Psychology, second edition. Upper Saddle River, NJ: Prentice Hall. Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Examples of Gestalt Principles
Sensation & Perception 11/17/2018 Examples of Gestalt Principles Similarity Things that are alike are perceived together Continuity Seeing lines that connect 1 to 2 and 3 to 4 in C Figure 3.23 from: Kassin, S. (1998). Psychology, second edition. Upper Saddle River, NJ: Prentice Hall. Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Depth and Distance Perception
Sensation & Perception 11/17/2018 Depth and Distance Perception Binocular Cues: Visual cues to depth or distance that require the use of both eyes Convergence: Turning inward of the eyes, which occurs when they focus on a nearby object Retinal Disparity: The slight difference in lateral separation between two objects as seen by the left eye and the right eye Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Depth and Distance Perception
Sensation & Perception 11/17/2018 Depth and Distance Perception Monocular Cues: Visual cues to depth or distance that can be used by one eye alone Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Monocular Cues to Depth
Copyright © 2007 Pearson Education Canada

11/17/2018 The Ames Room A specially built room that makes people seem to change size as they move around in it The room is not a rectangle, as viewers assume it is A single peephole prevents using binocular depth cues Figure 3.24 from: Kassin, S. (1998). Psychology, second edition. Upper Saddle River, NJ: Prentice Hall. Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

11/17/2018 Visual Constancies The accurate perception of objects as stable or unchanged despite changes in the sensory patterns they produce Shape constancy Location constancy Size constancy Brightness constancy Colour constancy Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Visual Illusions: Fooling the Eye
Sensation & Perception 11/17/2018 Visual Illusions: Fooling the Eye The cats in (a) are the same size The diagonal lines in (b) are parallel You can create a “floating fingertip frankfurter” by holding hands as shown, 5-10” in front of face Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

The Müller-Lyer Illusion
Sensation & Perception 11/17/2018 The Müller-Lyer Illusion Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

11/17/2018 The Ponzo Illusion Linear perspective provides context Side lines seem to converge Top line seems farther away But the retinal images of the red lines are equal! Figure 3.3Davis 2 from: Kassin, S. (1998). Psychology, second edition. Upper Saddle River, NJ: Prentice Hall. Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

11/17/2018 What We Hear Loudness The dimension of auditory experience related to the intensity of a pressure wave Pitch The dimension of auditory experience related to the frequency of a pressure wave Timbre (pronounced “TAM-bur”) The distinguishing quality of sound; the dimension of auditory experience related to the complexity of the pressure wave Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Auditory Localization
Sensation & Perception 11/17/2018 Auditory Localization Sounds from different directions are not identical as they arrive at left and right ears Loudness Timing Phase The brain calculates a sound’s location by using these differences Figure 3.14 from: Kassin, S. (1998). Psychology, second edition. Upper Saddle River, NJ: Prentice Hall. Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Taste: Savoury Sensations
Sensation & Perception 11/17/2018 Taste: Savoury Sensations Papillae Knoblike elevations on the tongue, containing the taste buds (Singular: papilla) Taste buds Nests of taste-receptor cells Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

11/17/2018 Taste Buds Photograph of tongue surface (top), magnified 75 times 10,000 taste buds line the tongue and mouth Taste receptors are down inside the “bud” Children have more taste buds than adults Figure 3.17 from: Kassin, S. (1998). Psychology, second edition. Upper Saddle River, NJ: Prentice Hall. Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

11/17/2018 Four Tastes Four basic tastes Salty, sour, bitter and sweet Different people have different tastes based on: Genetics Culture Learning Food attractiveness Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Smell: The Sense of Scents
Sensation & Perception 11/17/2018 Smell: The Sense of Scents Airborne chemical molecules enter the nose and circulate through the nasal cavity Vapours can also enter through the mouth and pass into nasal cavity Receptors on the roof of the nasal cavity detect these molecules Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Gate-Control Theory of Pain
Sensation & Perception 11/17/2018 Gate-Control Theory of Pain Experience of pain depends (in part) on whether the pain impulse gets past neurological “gate” in the spinal cord and thus reaches the brain Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Neuromatrix Theory of Pain
Sensation & Perception 11/17/2018 Neuromatrix Theory of Pain Theory that the matrix of neurons in the brain is capable of generating pain (and other sensations) in the absence of signals from sensory nerves Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

The Environment Within
Sensation & Perception 11/17/2018 The Environment Within Kinesthesis The sense of body position and movement of body parts; also called kinesthesia Equilibrium The sense of balance Semicircular Canals Sense organs in the inner ear, which contribute to equilibrium by responding to rotation of the head Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Perceptual Powers: Origins and Influences
Sensation & Perception 11/17/2018 Perceptual Powers: Origins and Influences Inborn abilities and the visual cliff Critical periods Psychological and cultural Influences on perception Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

11/17/2018 The Visual Cliff Glass surface, with checkerboard underneath at different heights Visual illusion of a cliff Baby can’t fall Mom stands across the gap Babies show increased attention over deep side at age 2 months, but aren’t afraid until about the age they can crawl (Gibson & Walk, 1960) Figure 3.27 from: Kassin, S. (2001). Psychology, third edition. Upper Saddle River, NJ: Prentice Hall. Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

11/17/2018 Critical Period If infants miss out on experiences during a crucial period of time, perception will be impaired When adults who have been blind since birth have vision restored, they may not see well Other senses such has hearing may be influenced similarly Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Psychological and Cultural Influences on Perception
Sensation & Perception 11/17/2018 Psychological and Cultural Influences on Perception We are more likely to perceive something when we need it What we believe can affect what we perceive Emotions, such as fear, can influence perceptions of sensory information Expectations based on our previous experiences influence how we perceive the world Perceptual Set A habitual way of perceiving, based on expectations All are influenced by our culture Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

11/17/2018 Perceptual Set What you see in the center figures depends on the order in which you look at the figures: If you scan from the left, see an old woman If you scan from the right, see a woman’s figure Figure 3.28 from: Kassin, S. (1998). Psychology, second edition. Upper Saddle River, NJ: Prentice Hall. Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

11/17/2018 Context Effects The same physical stimulus can be interpreted differently We use other cues in the situation to resolve ambiguities Is this the letter B or the number 13? Figure 3.Davis 29 from: Kassin, S. (1998). Psychology, second edition. Upper Saddle River, NJ: Prentice Hall. Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Subliminal Perception
Sensation & Perception 11/17/2018 Subliminal Perception Perceiving without awareness visual stimuli can affect your behaviour even when you are unaware that you saw it nonconscious processing also occurs in memory, thinking, and decision making these effects are often small, however, and difficult to demonstrate and work best with simple stimuli Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Perception versus Persuasion
Although subliminal priming can influence judgments and preferences, research doesn’t support its success in major levels of persuasion Copyright © 2007 Pearson Education Canada

Extrasensory Perception
Sensation & Perception 11/17/2018 Extrasensory Perception Extrasensory Perception (ESP): The ability to perceive something without ordinary sensory information This has not been scientifically demonstrated Three types of ESP: Telepathy – Mind-to-mind communication Clairvoyance – Perception of remote events Precognition – Ability to see future events Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

11/17/2018 Parapsychology J. B. Rhine conducted many experiments on ESP using stimuli such as these Rhine believed that his evidence supported the existence of ESP, but his findings were flawed Figure 3.33 from: Kassin, S. (1998). Psychology, second edition. Upper Saddle River, NJ: Prentice Hall. Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

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