Essentials of
Understanding Psychology
9th Edition
By Robert Feldman
PowerPoints by Kimberly Foreman
Revised for 9th Ed by Cathleen Hunt
Copyright McGraw-Hill, Inc. 2011
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Chapter 3:
Sensation and Perception
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MODULE 8:
Sensing the World Around Us
• What is sensation, and how do psychologists study it?
• What is the relationship between a physical stimulus and
the kinds of sensory responses that result from it?
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MODULE 8:
Sensing the World Around Us
• Sensation
– Activation of the sense organs by a source of physical energy
• Perception
– Sorting out, interpretation, analysis, and integration of stimuli
carried out by the sense organs and brain
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MODULE 8:
Sensing the World Around Us
• Stimulus
– Any passing source of physical energy that produces a response
in a sense organ
• Psychophysics
– Study of the relationship between the physical aspects of
stimuli and our psychological experience of them
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Absolute Thresholds:
Detecting What’s Out There
• Absolute Threshold
– Smallest intensity of a stimulus that must be present for it to be
detected
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Difference Thresholds:
Noticing Distinctions Between Stimuli
• Difference Threshold
– Smallest level of added (or reduced) stimulation required to
sense that a change in stimulation has occurred
• Just noticeable difference
• Weber’s law
– Just noticeable difference is a constant proportion of the intensity of
an initial stimulus
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Sensory Adaptation:
Turning Down Our Responses
• Adaptation
– An adjustment in sensory capacity after prolonged exposure to
unchanging stimuli
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MODULE 9: Vision:
Shedding Light on the Eye
• What basic processes underlie the sense of vision?
• How do we see colors?
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Basic Cells of the Eye
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Illuminating the Structure of the Eye
• Cornea
– Protects eye and refracts light
• Pupil
– Opening depends on amount of light in environment
• Iris
– Colored part of eye
• Lens
– Accommodation
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Illuminating the Structure of the Eye
• Reaching the Retina
– Light is converted to electrical impulses for transmission to the
brain
• Rods
– Receptor cells sensitive to light
• Cones
– Cone-shaped; responsible for sharp focus and color perception
– Concentrated in the fovea
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Illuminating the Structure of the Eye
• Sending the Message from the Eye to the Brain
– Optic nerve
• Ganglion cells
• Blind spot
• Optic chiasm
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Illuminating the Structure of the Eye
• Processing the Visual Message
– Takes place in the visual cortex of the brain
• Feature detection
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Color Vision and Color Blindness:
The Seven-Million-Color Spectrum
• Explaining Color Vision
– Trichromatic theory of color vision
• Suggests that there are three kinds of cones in the retina
– Blue-violet colors
– Green colors
– Yellow-red colors
» Not successful at explaining afterimages
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Color Vision and Color Blindness:
The Seven-Million-Color Spectrum
• Opponent-process theory of color vision
– Receptor cells are linked in pairs, working in opposition to each
other
• Blue-yellow
• Red-green
• Black-white
– Explains afterimages
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MODULE 10:
Hearing and the Other Senses
• What role does the ear play in the senses of sound,
motion, and balance?
• How do smell and taste function?
• What are the skin senses, and how do they relate to the
experience of pain?
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The Ear
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Sensing Sound
• Sound
– Movement of air molecules brought about by a source of
vibration
• Eardrum
– Vibrates when sound waves hit it
– Middle ear
• Hammer, anvil, stirrup
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Sensing Sound
• Inner Ear
– Changes sound vibrations into a form in which they can be
transmitted to the brain
• Cochlea
– Filled with fluid and vibrates in response to sound
• Basilar membrane
– Dividing cochlea into an upper chamber and lower chamber
– Covered with hair cells
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Sensing Sound
• The Physical Aspects of Sound
– Frequency
• Number of wave cycles that occur in a second
– Pitch
– Amplitude
• Spread between the up-and-down peaks and valleys of air pressure in a
sound wave as it travels through the air
– Decibels
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Sensing Sound
• Sorting Out Theories of Sound
– Place Theory of Hearing
• States that different areas of the basilar membrane respond to different
frequencies
– Frequency Theory of Hearing
• Suggests that the entire basilar membrane acts like a microphone,
vibrating as a whole in response to a sound
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Sensing Sound
Balance: The Ups and Downs of Life
• Vestibular System
– Semicircular canals
• Main structure of vestibular system
• Three tubes containing fluid that sloshes through them when the head
moves, signaling rotational or angular movement to the brain
– Otoliths
• Sense forward, backward, or up-and-down motion, as well as the pull of
gravity
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Smell
• Olfaction
– Sense of smell is sparked when the molecules of a substance
enter the nasal passages
• Olfactory cells
– Pheromones
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Taste
• Gustation
– Taste qualities
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•
•
•
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Sweet
Sour
Salty
Bitter
“Umami”
– Taste Buds
• Supertasters
• Nontasters
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The Skin Senses:
Touch, Pressure, Temperature, and Pain
• Substance P
• Gate-control Theory of Pain
– Particular nerve receptors in the spinal cord lead to specific
areas of the brain related to pain
• Acupuncture
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Managing Pain
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•
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•
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Medication
Nerve and brain stimulation
Light therapy
Hypnosis
Biofeedback and relaxation techniques
Surgery
Cognitive restructuring
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How Our Senses Interact
• Synesthesia
• Multimodal perception
– Brain collects the information from the individual sensory
systems and integrates and coordinates it
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MODULE 11: Perceptual Organization:
Constructing Our View of the World
• What principles underlie our organization of the visual
world and allow us to make sense of our environment?
• How are we able to perceive the world in three
dimensions when our retinas are capable of sensing only
two-dimensional images?
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MODULE 11: Perceptual Organization:
Constructing Our View of the World
• What clues do visual illusions give us about our
understanding of general perceptual mechanisms?
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The Gestalt Laws of Organization
• Series of principles that focus on the ways we organize bits
and pieces of information into meaningful wholes
– gestalts
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Top-Down and Bottom-Up Processing
• Top-Down Processing
– Perception is guided by higher-level knowledge, experience,
expectations, and motivations
• Bottom-Up Processing
– Consists of the progression of recognizing and processing
information from individual components of a stimulus and
moving to the perception of the whole
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Top-Down Processing
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Depth Perception
• Ability to view the world in three dimensions and to
perceive distance
– Largely due to the fact that we have two eyes
• Binocular disparity
• Monocular cues
– Motion parallax
– Relative size
– Texture gradient
– Linear perspective
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Perceptual Constancy
• Phenomenon in which physical objects are perceived as
unvarying and consistent despite changes in their
appearance or in the physical environment
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Motion Perception:
As the World Turns
• Cues about perception of motion
– The movement of an object across the retina is typically
perceived relative to some stable, unmoving background
– Movement of images across the retina
– We factor in information about our own head and eye
movements, along with information about changes in the retinal
image
– Apparent movement
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Perceptual Illusions:
The Deceptions of Perceptions
• Visual Illusions
– Physical stimuli that consistently produce errors in perception
• Muller-Lyer illusion
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Culture and Perception
• Cultural differences are reflected in depth perception
– Zulu vs. Westerner perspectives
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Subliminal Perception
• Perception of messages about which we have no
awareness
– Called priming
• Written word
• Sound
• Smell
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Extrasensory Perception (ESP)
• Perception that does not involve our known senses
– Most psychologists reject the existence of ESP, asserting that
there is no sound documentation of the phenomenon
– Psychological Bulletin
• “Anomalous process of information transfer” or psi
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