2. Learning Outcomes
• Define and differentiate between sensation and
perception.
• Identify the parts of the eye, describe the
properties of light and the theories of color
vision.
Learning Outcomes
3. Learning Outcomes
• Describe how visual perception is organized.
• Identify the parts of the ear; explain the sense of
hearing.
Learning Outcomes
4. Learning Outcomes
• Describe the chemical senses.
• Identify the skin senses and theoretical
explanations for pain.
Learning Outcomes
5. Learning Outcomes
• Describe the kinesthetic and vestibular senses.
• Explain why psychologists are skeptical about
extrasensory perception.
Learning Outcomes
7. What are Sensation and Perception?
• Sensation is the stimulation of sensory receptors
and transmission of sensory information to the
central nervous system.
• Perception is process by which sensations are
organized and interpreted to form an inner
representation of the world.
8. Absolute Threshold
• Weakest amount of a stimulus that can be
distinguished from no stimulus at all
– Detected 50% of the time
9. Subliminal Stimulation
• Sensory stimulation below a person’s absolute
threshold for conscious perception (subliminal
perception)
– Lipton Ice (Experiment)
10. Difference Threshold
• Minimum difference in magnitude of two stimuli
required to tell them apart
– Detected 50% of the time
• Weber’s constant
– Fraction of the intensity by which a source of
physical energy must be increased or
decreased so that a difference in intensity will
be perceived.
• Just noticeable difference (jnd)
– Minimum difference a person can detect
11. Weber’s Constant
• Weber’s constant
– Light – 2% of intensity
– Weight – 2% of weight
– Sound – one-third of 1% change in pitch
(frequency)
– Taste – 20% difference in saltiness
12. Signal-Detection Theory
• Stimulus characteristics and psychological factors
interact to influence whether a stimulus is
detected.
– Psychological factors such as learning,
motivation, and psychological states
13. Feature Detectors
• Neurons in the sensory cortex that first in
response to specific features of sensory
information such as lines or edges of objects
– visual – respond to lines, color, textures,
movement
– auditory – respond to pitch, loudness, etc.
14. Sensory Adaptation
The processes by which organisms become
more sensitive to stimuli that are low in
magnitude and less sensitive to stimuli that are
constant or ongoing in magnitude
15. Sensory Adaptation
• Sensitization
– Positive adaptation – the type of sensory
adaptation in which we become more sensitive
to stimuli that are low in magnitude
• Desensitization
– Negative adaptation – the type of sensory
adaptation in which we become less sensitive
to constant stimuli
17. Light
• Spectrum of electromagnetic energy
– Vary in wavelength
• Within visible light, color is determined by
wavelength
• Prism separates wavelengths
19. The Eye
• Light enters through a narrow opening
– Cornea – transparent eye cover
– Iris – muscle; colored part of the eye
– Pupil – opening in the iris
• Sensitive to light and emotion
20. The Eye
• Lens
– Changes in thickness for focusing
– Image is projected onto retina
• Light Sensitive Surface
– Retina
• Photoreceptors
–Rods, Cones, Bipolar and ganglion cells
21. The Eye
• Optic Nerve
– Axons of ganglion neurons form optic nerve
– Conducts sensory input to brain (occipital lobe)
23. Rods and Cones
• Cones
– Most densely packed in center of retina (fovea)
– Provide color vision
• Rods
– Provide vision in black and white
– More sensitive to dim light than cones
24. Visual Acuity
• Sharpness of vision; greatest in the fovea
• Blind spot
– Point in retina where ganglion cells converge
• Nearsightedness
– See close objects most clearly – Elongated eyeball – Distant
objects focus in front of retina
• Farsightedness
– See distant objects most clearly – Eyeball is too short – Images of
nearby objects are focused behind the retina
• Presbyopia
– A condition characterized by brittleness of the lens
25. Light Adaptation
• Dark adaptation
– Process of adjusting to lower lighting
• Cones reach maximum adaptation in about
10 minutes
• Rods continue to adapt up to 45 minutes
• Adaptation to bright light occurs within a minute
or so
26. Perceptual Dimensions of Color
• Hue (color)
– Wavelength of light
• Value
– Degree of brightness or darkness
• Saturation
– Intensity of color
28. Perceptual Dimensions of Color
• Color Wheel
– Bend the colors of the spectrum into a circle
• Warm and Cool Colors
– Green-blue side of color wheel – cool
– Yellow-orange-red side of color wheel – warm
29. Perceptual Dimensions of Color
• Complementary Colors
– Colors across from one another on color wheel
– Mix complementary colors = gray
• Refers to light not pigments
• Light is the source of all colors
– Pigments reflect and absorb light selectively
30.
31. Perceptual Dimensions of Color
• Afterimage
– Persistent sensations of color are followed by
perception of the complementary color when
the first color is removed
32. Theories of Color
• Trichromatic Theory
– the theory that color vision is made possible by
three types of cones, some of which respond
to red light, some to green, and some to blue
• Opponent-Process Theory
– the theory that color vision is made possible by
three types of cones, some of which respond
to red or green light, some to blue or yellow,
and some to the intensity of light
• Cannot respond to both at simultaneously
33. Color Blindness
• Trichromat
– Normal color vision
• Monochromat
– Totally color blind
• Dichromat
– Partial color blindness
– Discriminate between two colors
– More common in males (sex linked trait)
36. Visual Perception
• Process used to organize sensory impressions
caused by the light that strikes our eyes
• Sensation is a mechanical process
• Perception is an active process
– Involves experience, expectations and
motivations
39. Gestalt Rules for Perceptual Organization
• Proximity
– the perceptual tendency to group together
objects that are near one another
• Similarity
– the perceptual tendency to group together
objects that are similar in appearance
• Continuity
– the tendency to perceive a series of points or
lines as having unity
41. Gestalt Rules for Perceptual Organization
• Common Fate
– Elements moving together are grouped
together
• Closure
– Perception of a complete figure, even when
there are gaps in sensory information
42. Top-Down Versus Bottom-Up Processing
• Top-Down Processing
– Perception of the whole followed by perception
of the parts
• Bottom-Up Processing
– Perception of the parts leads to perception of
the whole
43. Perceptual Constancies
• Acquired through experience; creates stability
– Size Constancy
• the tendency to perceive an object as being the
same size even as the size of its retinal image
changes according to the object’s distance
– Color Constancy
• the tendency to perceive an object as being the
same color even though lighting conditions change
its appearance
44. Perceptual Constancies
• Acquired through experience; creates stability
– Brightness Constancy
• the tendency to perceive an object as being just as
bright even though lighting conditions change its
appearance
– Shape Constancy
• the tendency to perceive an object as being the
same shape although the retinal image varies in
shape as it rotates
45. Visual Illusions
• Hering-Helmholtz Illusion
– Perceive drawing as three-dimensional
• Müller-Lyer Illusion
– Interpret length of lines based on experience
48. Sound
• Sound waves require a medium; air or water
• Sound waves compress and expand molecules of
the medium, creating vibrations
– A single cycle of compression and expansion
is one wave of sound
• Human ear is sensitive to sound waves with
frequencies of 20 to 20,000 cycles per second
49. Pitch and Loudness
• Pitch
– Frequency (# of cycles per second)
– Expressed in hertz (Hz)
– Pitch of women’s voice is higher than men’s
• Loudness
– Height (amplitude) of sound waves
– Expressed in decibels (dB)
54. Directional Stereophonic Hearing
• 3D Type of Hearing that we cannot experience if
we only had one ear.
• In locating sound, Loudness and sequence in
which sounds reach the ear provide cues; may
turn head to clarify information
56. Parts of the Ear
• Outer Ear
– Funnels sound waves to the eardrum
• Middle Ear
– Eardrum, hammer, anvil and stirrup
– Acts as an amplifier
– Oval window – Round window
57. Parts of the Ear
• Inner Ear
– Cochlea
• Basilar membrane
• Organ of Corti
• Auditory nerve - the axon bundle that transmits
neural impulses from the organ of Corti to the
brain
58. Locating Sounds
• Loudness and sequence in which sounds reach
the ear provide cues
– May turn head to clarify information
59. Perception of Loudness and Pitch
• Related to number of receptor neurons on the
organ of Corti
– Sounds are perceived as louder when more
sensory neurons fire
60. Perception of Loudness and Pitch
• Place theory
– The theory that the pitch of a sound is
determined by the section of the basilar
membrane that vibrates in response to the
sound (Applies only to pitches at least 5,000 Hz)
• Frequency theory
– the theory that the pitch of a sound is reflected
in the frequency of the neural impulses that are
generated in response to the sound (20 to 1,000 Hz)
• Both theories work together
61. Deafness
• Conductive deafness
– Damage to middle ear
– Hearing aids can help
• Sensorineural deafness
– Damage to inner ear or auditory nerve
– Cochlear implants may help with damage to
inner ear, but not auditory nerve
63. Smell
• Odors trigger receptor neurons in olfactory
membrane (the nerve that transmits information
concerning odors from olfactory receptors to the
brain)
– Odors are sample molecules of substances in
the air
• Sensory information about odors is sent to the
brain through the olfactory nerve
• Odor contributes to flavor of foods
64. Taste
• Taste is sensed through taste cells
– Receptor neurons on taste buds
• Four primary taste qualities
– Sweet, sour, salty and bitter
– Umami (fifth basic taste) – savory
• Flavor of food depends on odor, texture,
temperature and taste
• Individuals have taste sensitivities
66. Touch and Pressure
• Skin sensory receptors fire when skin surface is
touched
– Active touching
• Some areas of the body are more sensitive
– Nerve endings are more densely packed
– More sensory cortex is devoted to perception
of sensations in those areas
67. Temperature
• Receptors are located just beneath the skin
– Skin temperature increases – receptors for
warmth fire
– Skin temperature decreases – receptors for
cold fire
• Sensations for temperature are relative
68. Pain
• Nociceptors in skin are stimulated
– Pain is usually sharpest where nerve endings
are densely packed
– Pain can be felt deep within body
– No nerve endings for pain in the brain
69. Pain
• Prostaglandins
– Facilitate transmission of pain message
– Heighten circulation to injured area
(inflammation)
– Pain-relieving drugs inhibit production of
prostaglandins
– Emotional response and response to stress
affect degree of pain
70. Phantom Limb Pain
• 2 out of 3 combat veterans with amputated limbs
report phantom limb pain
– May involve activation of nerves in the stump
of missing limb
– May also involve reorganization of motor and
somatosensory cortex
71. Gate Theory of Pain
• Nervous system can only process a limited
amount of stimulation
– Rubbing the pained area competes for neural
attention
– Closes the “gate” on pain messages to the
brain
72. Acupuncture
• Ancient Chinese method of pain control
– Research shows it stimulates nerves to the
hypothalamus releasing endorphins
– Endorphins are similar in structure and effect
to morphine
74. Kinesthesis
• Sense that informs you about the position and
motion of your body
– Sensory information is sent to the brain from
sensory organs in joints, tendons and muscles
75. Vestibular System
• Housed mainly in semicircular canals in your ears
• Monitor your body’s motion and position in
relation to gravity
76. ESP: Is There Perception WithoutESP: Is There Perception Without
Sensation?Sensation?
77. Extrasensory Perception - ESP
• Perception through means other than sensory
organs
– Precognition – Able to perceive future events
in advance
– Psychokinesis – Mentally manipulating or
moving objects
– Telepathy – Direct transmission of thought or
ideas from one person to another
– Clairvoyance – Perception of objects that do
not stimulate sensory organs
78. Existence of ESP
• Ganzfeld Procedure
– Method for studying the existence of ESP
• No reliable evidence for existence of ESP
Editor's Notes
LO1 Define and differentiate between sensation and perception.
Truth or Fiction? People have five senses. FALSE People have many more than five senses. Touch is just one of your “skin senses” which also include pressure, warmth, cold, and pain. There are also senses that alert you to your own body position without your having to watch every step you take.
sensation – the stimulation of sensory receptors and the transmission of sensory information to the central nervous system
perception – the process by which sensations are organized into an inner representation of the world
Truth or Fiction? If we could see waves of light with slightly longer wavelengths, warm-blooded animals would glow in the dark. TRUE If you could see light with slightly longer wavelengths, you would see infrared light waves. Since heat generates infrared light, warm-blooded people, including other people would glow in the dark.
absolute threshold – the minimal amount of energy that can produce a sensation
Vision – a candle flame viewed from about 30 miles on a clear night
Hearing – a watch ticking from about 20 feet away in a quiet room
Taste – 1 teaspoon of sugar dissolved in 2 gallons of water
Smell – about one drop of perfume diffused though a small house
Touch – the pressure of the wing of a fly falling on a check about a distance of about .4 inch
Truth or Fiction? If we could see waves of light with slightly longer wavelengths, warm-blooded animals would glow in the dark. TRUE If you could see light with slightly longer wavelengths, you would see infrared light waves. Since heat generates infrared light, warm-blooded people, including other people would glow in the dark.
absolute threshold – the minimal amount of energy that can produce a sensation
Vision – a candle flame viewed from about 30 miles on a clear night
Hearing – a watch ticking from about 20 feet away in a quiet room
Taste – 1 teaspoon of sugar dissolved in 2 gallons of water
Smell – about one drop of perfume diffused though a small house
Touch – the pressure of the wing of a fly falling on a check about a distance of about .4 inch
difference threshold – the minimal difference in intensity required between two sources of energy so that they will be perceived as being different
Weber’s constant – the fraction of the intensity by which a source of physical energy must be increased or decreased so that a difference in intensity will be perceived.
Light – 2% of intensity
Weight – 2% of weight
Sound – one-third of 1% change in pitch (frequency)
Taste – 20% difference in saltiness
just noticeable difference (jnd) – the minimal amount by which a source of energy must be increased or decreased so that a difference in intensity will be perceived
difference threshold – the minimal difference in intensity required between two sources of energy so that they will be perceived as being different
Weber’s constant – the fraction of the intensity by which a source of physical energy must be increased or decreased so that a difference in intensity will be perceived.
Light – 2% of intensity
Weight – 2% of weight
Sound – one-third of 1% change in pitch (frequency)
Taste – 20% difference in saltiness
just noticeable difference (jnd) – the minimal amount by which a source of energy must be increased or decreased so that a difference in intensity will be perceived
Truth or Fiction? People sometimes hear what they want to hear. TRUE Sometimes we detect stimuli we are searching for.
signal-detection theory – the view that the perception of sensory stimuli involves the interaction of physical, biological, and psychological factors
Stimulus characteristics – intensity of signal, degree to which signal can be distinguished from background, individual’s sensory system
Psychological factors – learning, motivation, psychological states (fatigue, alertness)
feature detectors – neurons in the sensory cortex that first in response to specific features of sensory information such as lines or edges of objects
sensory adaptation – the processes by which organisms become more sensitive to stimuli that are low in magnitude and less sensitive to stimuli that are constant or ongoing in magnitude
sensitization – the type of sensory adaptation in which we become more sensitive to stimuli that are low in magnitude. Also called positive adaptation
desensitization – the type of sensory adaptation in which we become less sensitive to constant stimuli. Also called negative adaptation
sensory adaptation – the processes by which organisms become more sensitive to stimuli that are low in magnitude and less sensitive to stimuli that are constant or ongoing in magnitude
sensitization – the type of sensory adaptation in which we become more sensitive to stimuli that are low in magnitude. Also called positive adaptation
desensitization – the type of sensory adaptation in which we become less sensitive to constant stimuli. Also called negative adaptation
LO2 Identify the parts of the eye, describe the properties of light and the theories of color vision.
Figure 4.1 The Visible Spectrum. By passing a source of white light, such as sunlight, through a prism, we break it down into the colors of the visible spectrum. The visible spectrum is just a narrow segment of the electromagnetic spectrum. The electromagnetic spectrum also includes radio waves, microwaves, X-rays, cosmic rays, and many others. Different forms of electromagnetic energy have wave-lengths that vary from a few trillonths of a meter to thousands of miles. Visible light varies in wave-length from about 400- to 700- billionths of a meter. (One meter = 39.37 inches.)
cornea – transparent tissue forming the outer surface of the eyeball
iris – a muscular membrane whose dilation regulates the amount of light that enters the eye
pupil – the black-looking opening in the center of the iris, through which light enters the eye
lens – a transparent body behind the iris that focuses an image on the retina
retina – the area of the inner surface of the eye that contains rods and cones
photoreceptors – cells that respond to light
bipolar cells – neurons that conduct neural impulses from rods and cones to ganglion cells
ganglion cells – neurons whose axons form the optic nerve
optic nerve – the nerve that transmits sensory information from the eye to the brain
Figure 4.2 The Human Eye In both the eye and a camera, light enters through a narrow opening and is projected onto a sensitive surface. In the eye, the photosensitive surface is called the retina, and information concerning the changing images on the retina is transmitted to the brain. The retina contains photoreceptors called rods and cones. Rods and cones transmit sensory input back through the bipolar neurons to the ganglion neurons. The axons of the ganglion neurons form the optic nerve, which transmits sensory stimulation through the rain to the visual cortex of the occipital lobe.
Go to 4ltrpress.cengage.com/psych to access an interactive version of this figure.
rods – rod shaped photoreceptors that are sensitive only to the intensity of light
cones – cone-shaped photoreceptors that transmit sensations of color
See Figure 4.3 in textbook for active illustration of the blind spot.
fovea – an area near the center of the retina that is dense with cones and where vision is consequently most acute
blind spot – the area of the retina where axons from ganglion cells meet to form the optic nerve
visual acuity – sharpness of vision
presbyopia – a condition characterized by brittleness of the lens
Nearsightedness – See close objects most clearly – Elongated eyeball – Distant objects focus in front of retina
Farsightedness – See distant objects most clearly – Eyeball is too short – Images of nearby objects are focused behind the retina
dark adaptation – the process of adjusting to conditions of lower lighting by increasing the sensitivity of rods and cones
Figure 4.4 The Color Wheel.
Truth or Fiction? When we mix blue and yellow light, we obtain green light. FALSE If we mix blue and yellow light (complementary colors) we obtain gray.
complementary – descriptive of colors of the spectrum that when combined produce white or nearly white light
Light is the source of all colors – Mixture of light is additive
Pigments reflect and absorb light selectively – Mixture of pigments is subtractive
Figure 4.6 Place a sheet of white paper beneath the book, and star at the black dot in the center of the flag for at least 30 seconds. Then remove the book. The afterimage on the paper beneath will look familiar.
In the classroom, have students stare at the black dot in the center of the flag for at least 30 seconds. Then look at a white wall and the afterimage will appear.
afterimage – the lingering visual impression made by a stimulus that has been removed
trichromatic theory – the theory that color vision is made possible by three types of cones, some of which respond to red light, some to green, and some to blue
opponent-process theory – the theory that color vision is made possible by three types of cones, some of which respond to red or green light, some to blue or yellow, and some to the intensity of light
trichromat – a person with normal color vision
monochromat – a person who is sensitive to black and white only and hence color-blind
dichromat – a person who is sensitive to black-white and either red-green or blue-yellow and hence partially color-blind
Figure 4.7 Plates from a Test for Color Blindness. Can you see the numbers in these plates from a test for color blindness? A person with red-green color blindness would not be able to see the 6, and a person with blue-yellow color blindness would probably not discern the 12. (Caution. These reproductions cannot be used for actual testing of color blindness.)
LO3 Describe how visual perception is organized.
Example of Figure and Ground are available in the textbook, Figure 4.9.
Go to 4ltrpress.cengage.com/psych to access an interactive version of this figure.
Figure 4.9 The Rubin Vase
Go to 4ltrpress.cengage.com/psych to access an interactive version of this figure.
proximity – nearness; the perceptual tendency to group together objects that are near one another
similarity – the perceptual tendency to group together objects that are similar in appearance
continuity – the tendency to perceive a series of points or lines as having unity
Figure 4.10 Some Gestalt Laws of Perceptual Organization. These drawings illustrate the Gestalt laws of proximity, similarity, continuity, and closure.
common fate – the tendency to perceive elements that move together as belonging together
closure – the tendency to perceive a broken figure as being complete or whole
top-down processing – the use of contextual information or knowledge of a pattern in order to organize parts of the pattern
bottom-up processing – the organization of the parts of a pattern to recognize, or form an image of, the pattern they compose
size constancy – the tendency to perceive an object as being the same size even as the size of its retinal image changes according to the object’s distance
color constancy – the tendency to perceive an object as being the same color even though lighting conditions change its appearance
brightness constancy – the tendency to perceive an object as being just as bright even though lighting conditions change its appearance
shape constancy – the tendency to perceive an object as being the same shape although the retinal image varies in shape as it rotates
size constancy – the tendency to perceive an object as being the same size even as the size of its retinal image changes according to the object’s distance
color constancy – the tendency to perceive an object as being the same color even though lighting conditions change its appearance
brightness constancy – the tendency to perceive an object as being just as bright even though lighting conditions change its appearance
shape constancy – the tendency to perceive an object as being the same shape although the retinal image varies in shape as it rotates
For some on-line examples of many of the visual phenomena, see Project Lite, an atlas of visual phenomena, created by Kenneth Brecher and Scott Gorlin and funded by an NSF Grant at http://lite.bu.edu/vision/applets/lite/lite/lite.html
Figure 4.13 The Hering-Helmholtz Illusion and Müller-Lyler Illusions In the Hering-Helmholtz illusion, are the horizontal lines straight or curved? In the Müller-Lyler illusion, are the vertical lines equal in length?
Go to 4ltrpress.cengage.com/psych to access an interactive version of this figure.
LO4 Identify the parts of the ear; explain the sense of hearing.
hertz (Hz) – a unit expressing the frequency of sound waves. One hertz equals one cycle per second
decibel (dB) – a unit expressing the loudness of a sound
Pitch of women’s voice is higher than men’s
Women’s vocal cords are usually shorter
Vocal cords vibrate at a greater frequency
Figure 4.14 Sound Waves of Various Frequencies and Amplitudes. Which sounds have the highest pitch? Which are loudest?
Figure 4.15 Decibel Ratings of Familiar Sounds. Zero dB is the threshold of hearing. You may suffer hearing loss if you incur prolonged exposure to sounds of 85 to 90 dB.
Directional s
Figure 4.16 The Human Ear.
Go to 4ltrpress.cengage.com/psych to access an interactive version of this figure.
cochlea – the inner ear; the bony tube that contains the basilar membrane and the organ of Corti
basilar membrane – a membrane that lies coiled within the cochlea
organ of Corti – the receptor for hearing that lies on the basilar membrane in the cochlea
auditory nerve – the axon bundle that transmits neural impulses from the organ of Corti to the brain
You can have students try the “Virtual Barber Shop” at home (requires headphones to be appreciated fully). Check it out at http://youtube.com/watch?v=IUDTlvagjJA
place theory – the theory that the pitch of a sound is determined by the section of the basilar membrane that vibrates in response to the sound
Applies only to pitches at least 5,000 Hz
frequency theory – the theory that the pitch of a sound is reflected in the frequency of the neural impulses that are generated in response to the sound
Best explains pitches between 20 and 1,000 Hz
Both theories work together - Explain perception of pitches between 1,000 and 5,000
LO5 Describe the chemical senses.
flavor – a complex quality of food and other substances that is based on their odor, texture, and temperature as well their taste
olfactory nerve – the nerve that transmits information concerning odors from olfactory receptors to the brain
taste cells – receptor cells that are sensitive to taste
taste buds – the sensory organs for taste. They contain taste cells and are located mostly on the tongue
LO6 Identify the skin senses and theoretical explanations for pain.
Truth or Fiction? Many people experience pain “in” limbs that have been amputated. True About 2 out of 3 combat veterans with amputated limbs report feeling pain in missing, or “phantom,” limbs.
LO7 Describe the kinesthetic and vestibular senses.
kinesthesis – the sense that informs us about the positions and motion of parts of our bodies
LO8 Explain why psychologists are skeptical about extrasensory perception.
Precognition – Able to perceive future events in advance
Psychokinesis – Mentally manipulating or moving objects
Telepathy – Direct transmission of thought or ideas from one person to another
Clairvoyance – Perception of objects that do not stimulate sensory organs
Truth or Fiction? Some people can read other people’s minds. FALSE There is no adequate scientific evidence that people can read other people’s minds.
