3. CHAPTER 5

4. CHAPTER 5
Sensation & Perception

6. WHAT IS A SENSE?

7. WHAT IS A SENSE?
A system that transmits information to the brain, e.g. sight,
touch, taste, sound, and smell

8. WHAT IS A SENSE?
A system that transmits information to the brain, e.g. sight,
touch, taste, sound, and smell
The senses convert characteristics of the physical world into
nervous system activity, thereby allowing us to “sense” the
world around us

9. WHAT IS A SENSE?
A system that transmits information to the brain, e.g. sight,
touch, taste, sound, and smell
The senses convert characteristics of the physical world into
nervous system activity, thereby allowing us to “sense” the
world around us
Sensation IS NOT the same as perception (subjective
experience of sensations)

11. SENSATION IS THE PROCESS BY WHICH WE
RECEIVE INFORMATION FROM THE
ENVIRONMENT.

12. SENSATION IS THE PROCESS BY WHICH WE
RECEIVE INFORMATION FROM THE
ENVIRONMENT.
What kind of information?

13. SENSATION IS THE PROCESS BY WHICH WE
RECEIVE INFORMATION FROM THE
ENVIRONMENT.
What kind of information?
A stimulus is a detectable input from the environment:

14. SENSATION IS THE PROCESS BY WHICH WE
RECEIVE INFORMATION FROM THE
ENVIRONMENT.
What kind of information?
A stimulus is a detectable input from the environment:
1. Light—vision

15. SENSATION IS THE PROCESS BY WHICH WE
RECEIVE INFORMATION FROM THE
ENVIRONMENT.
What kind of information?
A stimulus is a detectable input from the environment:
1. Light—vision
2. Sound—hearing

16. SENSATION IS THE PROCESS BY WHICH WE
RECEIVE INFORMATION FROM THE
ENVIRONMENT.
What kind of information?
A stimulus is a detectable input from the environment:
1. Light—vision
2. Sound—hearing
3. Chemicals—taste and smell

17. SENSATION IS THE PROCESS BY WHICH WE
RECEIVE INFORMATION FROM THE
ENVIRONMENT.
What kind of information?
A stimulus is a detectable input from the environment:
1. Light—vision
2. Sound—hearing
3. Chemicals—taste and smell
4. Pressure, temperature, pain—sense of touch

18. SENSATION IS THE PROCESS BY WHICH WE
RECEIVE INFORMATION FROM THE
ENVIRONMENT.
What kind of information?
A stimulus is a detectable input from the environment:
1. Light—vision
2. Sound—hearing
3. Chemicals—taste and smell
4. Pressure, temperature, pain—sense of touch
5. Orientation, balance—kinesthetic senses

20. ENVIRONMENTAL INFORMATION (STIMULI)
EXISTS IN MANY FORMS:

21. ENVIRONMENTAL INFORMATION (STIMULI)
EXISTS IN MANY FORMS:
A physical stimulus must first be introduced. For example:
air vibrations, gases, chemicals, tactile pressures

22. ENVIRONMENTAL INFORMATION (STIMULI)
EXISTS IN MANY FORMS:
A physical stimulus must first be introduced. For example:
air vibrations, gases, chemicals, tactile pressures
Our senses respond to a limited range of environmental
stimuli. For example, we cannot hear sound of frequencies
above 20,000 Hz, even though dogs can hear them.

24. SOME PHYSICAL STIMULI THAT OUR BODIES
ARE SENSITIVE TO:

25. SOME PHYSICAL STIMULI THAT OUR BODIES
ARE SENSITIVE TO:
Light as experienced through vision

26. SOME PHYSICAL STIMULI THAT OUR BODIES
ARE SENSITIVE TO:
Light as experienced through vision
a. Visible light is part of the electromagnetic spectrum.

27. SOME PHYSICAL STIMULI THAT OUR BODIES
ARE SENSITIVE TO:
Light as experienced through vision
a. Visible light is part of the electromagnetic spectrum.
b. Properties of light {Intensity (experienced as brightness);Wavelength (experienced as hue);Complexity or
purity (experienced as saturation)

28. SOME PHYSICAL STIMULI THAT OUR BODIES
ARE SENSITIVE TO:
Light as experienced through vision
a. Visible light is part of the electromagnetic spectrum.
b. Properties of light {Intensity (experienced as brightness);Wavelength (experienced as hue);Complexity or
purity (experienced as saturation)
Sound as experienced through audition

29. SOME PHYSICAL STIMULI THAT OUR BODIES
ARE SENSITIVE TO:
Light as experienced through vision
a. Visible light is part of the electromagnetic spectrum.
b. Properties of light {Intensity (experienced as brightness);Wavelength (experienced as hue);Complexity or
purity (experienced as saturation)
Sound as experienced through audition
Properties of sound {Intensity (influences mainly loudness); Frequency (influences mainly pitch); Wave
form (influences mainly timbre); As noted above, there is not a one-to-one relationship between physical
properties and perceptual experience. For example, intensity can also influence perception of pitch.

31. SENSORY PROCESSES ARE THE INITIAL STEPS
TO PERCEPTION

32. SENSORY PROCESSES ARE THE INITIAL STEPS
TO PERCEPTION
1. Transduction is the process of converting energy of a stimulus into neural
activity. The stimulus is recoded as a neural pattern.

33. SENSORY PROCESSES ARE THE INITIAL STEPS
TO PERCEPTION
1. Transduction is the process of converting energy of a stimulus into neural
activity. The stimulus is recoded as a neural pattern.
2. Transduction can be affected by our experiences, such as through adaptation;
a constant level of stimulus results in a decreased response over time. With
continued exposure, the neural response to the stimulus may change. Adaption
is also perceptual, not just sensory.

35. SENSATION

36. SENSATION
Begins with sensory receptors (specialized cells that respond to particular types of energy)

37. SENSATION
Begins with sensory receptors (specialized cells that respond to particular types of energy)
Three types of sensory receptors: Photoreceptors (activated by electromagnetic energy), Chemoreceptors
(respond to chemical substances), Mechanoreceptors (respond to mechanical energy)

38. SENSATION
Begins with sensory receptors (specialized cells that respond to particular types of energy)
Three types of sensory receptors: Photoreceptors (activated by electromagnetic energy), Chemoreceptors
(respond to chemical substances), Mechanoreceptors (respond to mechanical energy)
Absolute threshold (the minimum intensity of a stimulus that will stimulate a sense organ to operate) varies
by individual due to unique response factors

39. SENSATION
Begins with sensory receptors (specialized cells that respond to particular types of energy)
Three types of sensory receptors: Photoreceptors (activated by electromagnetic energy), Chemoreceptors
(respond to chemical substances), Mechanoreceptors (respond to mechanical energy)
Absolute threshold (the minimum intensity of a stimulus that will stimulate a sense organ to operate) varies
by individual due to unique response factors
Habituation, a simple type of learning, refers to the tendency of neurons to become less sensitive to
constant or familiar stimuli

40. SENSATION
Begins with sensory receptors (specialized cells that respond to particular types of energy)
Three types of sensory receptors: Photoreceptors (activated by electromagnetic energy), Chemoreceptors
(respond to chemical substances), Mechanoreceptors (respond to mechanical energy)
Absolute threshold (the minimum intensity of a stimulus that will stimulate a sense organ to operate) varies
by individual due to unique response factors
Habituation, a simple type of learning, refers to the tendency of neurons to become less sensitive to
constant or familiar stimuli
Just noticeable difference (JND) refers to receptor cells’ ability to detect subtle changes in stimulus strength

41. SENSATION
Begins with sensory receptors (specialized cells that respond to particular types of energy)
Three types of sensory receptors: Photoreceptors (activated by electromagnetic energy), Chemoreceptors
(respond to chemical substances), Mechanoreceptors (respond to mechanical energy)
Absolute threshold (the minimum intensity of a stimulus that will stimulate a sense organ to operate) varies
by individual due to unique response factors
Habituation, a simple type of learning, refers to the tendency of neurons to become less sensitive to
constant or familiar stimuli
Just noticeable difference (JND) refers to receptor cells’ ability to detect subtle changes in stimulus strength
The relationship of sensation to change in stimulus strength is known as Weber’s Law

43. SIGHT

44. SIGHT

45. SIGHT
Our most dominant sense with more of our brain involved in
sight than any other sense

46. SIGHT
Our most dominant sense with more of our brain involved in
sight than any other sense
Human sight is the sensation of reflected electromagnetic
radiation; the light’s wavelength is seen as color; the light’s
amplitude is experienced as brightness or intensity

48. HOW DO OUR EYES
WORK?

49. HOW DO OUR EYES
WORK?
Sclera: mostly “white part” of eye that provides protection and structure

50. HOW DO OUR EYES
WORK?
Sclera: mostly “white part” of eye that provides protection and structure
The cornea refracts light into the iris; specialized, transparent portion of the sclera through which light
enters

51. HOW DO OUR EYES
WORK?
Sclera: mostly “white part” of eye that provides protection and structure
The cornea refracts light into the iris; specialized, transparent portion of the sclera through which light
enters
The iris is the pigmented muscle that gives the eye its color and regulates the size of the pupil. The muscles
of the iris control the amount of light entering the eye.

52. HOW DO OUR EYES
WORK?
Sclera: mostly “white part” of eye that provides protection and structure
The cornea refracts light into the iris; specialized, transparent portion of the sclera through which light
enters
The iris is the pigmented muscle that gives the eye its color and regulates the size of the pupil. The muscles
of the iris control the amount of light entering the eye.
The pupillary reflex opens and closes the pupil, the opening in iris

53. HOW DO OUR EYES
WORK?
Sclera: mostly “white part” of eye that provides protection and structure
The cornea refracts light into the iris; specialized, transparent portion of the sclera through which light
enters
The iris is the pigmented muscle that gives the eye its color and regulates the size of the pupil. The muscles
of the iris control the amount of light entering the eye.
The pupillary reflex opens and closes the pupil, the opening in iris
The lens focuses the image onto the retina; lens is the transparent, shape-changing convex structure that
focuses images on the retina. The lens must accommodate in order to focus on a specific object. The ciliary
muscles relax for objects in the distance and constrict, which thickens the lens, for close items.

54. HOW DO OUR EYES
WORK?
Sclera: mostly “white part” of eye that provides protection and structure
The cornea refracts light into the iris; specialized, transparent portion of the sclera through which light
enters
The iris is the pigmented muscle that gives the eye its color and regulates the size of the pupil. The muscles
of the iris control the amount of light entering the eye.
The pupillary reflex opens and closes the pupil, the opening in iris
The lens focuses the image onto the retina; lens is the transparent, shape-changing convex structure that
focuses images on the retina. The lens must accommodate in order to focus on a specific object. The ciliary
muscles relax for objects in the distance and constrict, which thickens the lens, for close items.
The retina, layer containing two types of photoreceptors—rods and cones—that transduce light energy to
electrochemical energy. Rods are most sensitive to low levels of light and cones are sensitive to high light
levels of light and are responsible for color vision and vision acuity. Cones are most concentrated in the
fovea, the center of the field of vision

55. HOW DO OUR EYES
WORK?
Sclera: mostly “white part” of eye that provides protection and structure
The cornea refracts light into the iris; specialized, transparent portion of the sclera through which light
enters
The iris is the pigmented muscle that gives the eye its color and regulates the size of the pupil. The muscles
of the iris control the amount of light entering the eye.
The pupillary reflex opens and closes the pupil, the opening in iris
The lens focuses the image onto the retina; lens is the transparent, shape-changing convex structure that
focuses images on the retina. The lens must accommodate in order to focus on a specific object. The ciliary
muscles relax for objects in the distance and constrict, which thickens the lens, for close items.
The retina, layer containing two types of photoreceptors—rods and cones—that transduce light energy to
electrochemical energy. Rods are most sensitive to low levels of light and cones are sensitive to high light
levels of light and are responsible for color vision and vision acuity. Cones are most concentrated in the
fovea, the center of the field of vision
The optic nerve extends from the eye, across the optic chiasm (the junction of the two optic nerves where
fibers from the nasal sides of the two retinas cross, but the nerve fibers from the peripheral sides of the two
retinas do not cross to the other side of the brain leading to the result that the left half of the world is
represented in the right hemisphere of the brain and vice-versa) to the cerebral hemisphere

56. HOW DO OUR EYES
WORK?
Sclera: mostly “white part” of eye that provides protection and structure
The cornea refracts light into the iris; specialized, transparent portion of the sclera through which light
enters
The iris is the pigmented muscle that gives the eye its color and regulates the size of the pupil. The muscles
of the iris control the amount of light entering the eye.
The pupillary reflex opens and closes the pupil, the opening in iris
The lens focuses the image onto the retina; lens is the transparent, shape-changing convex structure that
focuses images on the retina. The lens must accommodate in order to focus on a specific object. The ciliary
muscles relax for objects in the distance and constrict, which thickens the lens, for close items.
The retina, layer containing two types of photoreceptors—rods and cones—that transduce light energy to
electrochemical energy. Rods are most sensitive to low levels of light and cones are sensitive to high light
levels of light and are responsible for color vision and vision acuity. Cones are most concentrated in the
fovea, the center of the field of vision
The optic nerve extends from the eye, across the optic chiasm (the junction of the two optic nerves where
fibers from the nasal sides of the two retinas cross, but the nerve fibers from the peripheral sides of the two
retinas do not cross to the other side of the brain leading to the result that the left half of the world is
represented in the right hemisphere of the brain and vice-versa) to the cerebral hemisphere
There are no rods or cones at the blind spot where the optic nerve leaves the eye.

58. HEARING

59. HEARING

60. HEARING
The sensation and perception of sounds

61. HEARING
The sensation and perception of sounds
Sounds are pressure changes or waves passing through the
air

62. HEARING
The sensation and perception of sounds
Sounds are pressure changes or waves passing through the
air
Sound frequency is perceived as loudness and frequency as
pitch

64. HOW DO OUR EARS
WORK?

65. HOW DO OUR EARS
WORK?
The outer ear directs sound down the auditory canal to the tympanic membrane,
the vibrations from which pass through a series of small bones in the middle ear
called the ossicles

66. HOW DO OUR EARS
WORK?
The outer ear directs sound down the auditory canal to the tympanic membrane,
the vibrations from which pass through a series of small bones in the middle ear
called the ossicles
The ossicles magnify the eardrum’s vibrations and transmit them to the inner ear
via the oval window

67. HOW DO OUR EARS
WORK?
The outer ear directs sound down the auditory canal to the tympanic membrane,
the vibrations from which pass through a series of small bones in the middle ear
called the ossicles
The ossicles magnify the eardrum’s vibrations and transmit them to the inner ear
via the oval window
The cochlea is a snail-shaped fluid-filled structure lined with the basilar
membrane

68. HOW DO OUR EARS
WORK?
The outer ear directs sound down the auditory canal to the tympanic membrane,
the vibrations from which pass through a series of small bones in the middle ear
called the ossicles
The ossicles magnify the eardrum’s vibrations and transmit them to the inner ear
via the oval window
The cochlea is a snail-shaped fluid-filled structure lined with the basilar
membrane
The basilar membrane is covered with stereocilia that connect with the auditory
nerve

70. SMELL
(OLFACTORY SYSTEM)

71. SMELL
(OLFACTORY SYSTEM)
Detects airborne chemicals that we experience as an odor

72. SMELL
(OLFACTORY SYSTEM)
Detects airborne chemicals that we experience as an odor
Olfactory receptors in the mucus membrane (olfactory
epithelium) at the roof of the nasal cavity connect to the
olfactory nerve and feed into the brain

73. SMELL
(OLFACTORY SYSTEM)
Detects airborne chemicals that we experience as an odor
Olfactory receptors in the mucus membrane (olfactory
epithelium) at the roof of the nasal cavity connect to the
olfactory nerve and feed into the brain
We have receptors that are sensitive to thousands of
airborne chemicals, but what we experience as an odor is
usually a pattern of responses to a variety of chemicals

75. HOW DOES THE NOSE
WORK?

76. HOW DOES THE NOSE
WORK?
Olfactory cells carry information to the olfactory bulb. The olfactory bulb activates the prefrontal cortex.

77. HOW DOES THE NOSE
WORK?
Olfactory cells carry information to the olfactory bulb. The olfactory bulb activates the prefrontal cortex.
Olfactory receptor neurons have a life cycle of about 30 days and are continually created.

78. HOW DOES THE NOSE
WORK?
Olfactory cells carry information to the olfactory bulb. The olfactory bulb activates the prefrontal cortex.
Olfactory receptor neurons have a life cycle of about 30 days and are continually created.
Olfactory cells in the olfactory epithelium are stimulated by gases dissolved in the fluid covering the
membrane.

79. HOW DOES THE NOSE
WORK?
Olfactory cells carry information to the olfactory bulb. The olfactory bulb activates the prefrontal cortex.
Olfactory receptor neurons have a life cycle of about 30 days and are continually created.
Olfactory cells in the olfactory epithelium are stimulated by gases dissolved in the fluid covering the
membrane.
For a stimulus to be smelled, it must be dissolved.

80. HOW DOES THE NOSE
WORK?
Olfactory cells carry information to the olfactory bulb. The olfactory bulb activates the prefrontal cortex.
Olfactory receptor neurons have a life cycle of about 30 days and are continually created.
Olfactory cells in the olfactory epithelium are stimulated by gases dissolved in the fluid covering the
membrane.
For a stimulus to be smelled, it must be dissolved.
Odors or scents stimulate the olfactory epithelium.

81. HOW DOES THE NOSE
WORK?
Olfactory cells carry information to the olfactory bulb. The olfactory bulb activates the prefrontal cortex.
Olfactory receptor neurons have a life cycle of about 30 days and are continually created.
Olfactory cells in the olfactory epithelium are stimulated by gases dissolved in the fluid covering the
membrane.
For a stimulus to be smelled, it must be dissolved.
Odors or scents stimulate the olfactory epithelium.
Odors can evoke highly emotional memories (e.g., Herz, 2004).

82. HOW DOES THE NOSE
WORK?
Olfactory cells carry information to the olfactory bulb. The olfactory bulb activates the prefrontal cortex.
Olfactory receptor neurons have a life cycle of about 30 days and are continually created.
Olfactory cells in the olfactory epithelium are stimulated by gases dissolved in the fluid covering the
membrane.
For a stimulus to be smelled, it must be dissolved.
Odors or scents stimulate the olfactory epithelium.
Odors can evoke highly emotional memories (e.g., Herz, 2004).
On average, women detect odors more readily than men. Also, brain responses to odors are stronger in
women than in men (Kalat, 2007).

83. HOW DOES THE NOSE
WORK?
Olfactory cells carry information to the olfactory bulb. The olfactory bulb activates the prefrontal cortex.
Olfactory receptor neurons have a life cycle of about 30 days and are continually created.
Olfactory cells in the olfactory epithelium are stimulated by gases dissolved in the fluid covering the
membrane.
For a stimulus to be smelled, it must be dissolved.
Odors or scents stimulate the olfactory epithelium.
Odors can evoke highly emotional memories (e.g., Herz, 2004).
On average, women detect odors more readily than men. Also, brain responses to odors are stronger in
women than in men (Kalat, 2007).
Pheromones: same-species odors, used as a form of chemical communication

84. HOW DOES THE NOSE
WORK?
Olfactory cells carry information to the olfactory bulb. The olfactory bulb activates the prefrontal cortex.
Olfactory receptor neurons have a life cycle of about 30 days and are continually created.
Olfactory cells in the olfactory epithelium are stimulated by gases dissolved in the fluid covering the
membrane.
For a stimulus to be smelled, it must be dissolved.
Odors or scents stimulate the olfactory epithelium.
Odors can evoke highly emotional memories (e.g., Herz, 2004).
On average, women detect odors more readily than men. Also, brain responses to odors are stronger in
women than in men (Kalat, 2007).
Pheromones: same-species odors, used as a form of chemical communication
Anosmia is the loss or lack of sense of smell. Specific anosmia is the inability to smell a single chemical.

86. TASTE
(GUSTATORY SYSTEM)

87. TASTE
(GUSTATORY SYSTEM)
Detects chemicals that come into contact with the tongue

88. TASTE
(GUSTATORY SYSTEM)
Detects chemicals that come into contact with the tongue
What we experience as taste is actually more about smell than taste

89. TASTE
(GUSTATORY SYSTEM)
Detects chemicals that come into contact with the tongue
What we experience as taste is actually more about smell than taste
Taste receptor cells, gustatory cells, are clustered in papillae on the tongue

90. TASTE
(GUSTATORY SYSTEM)
Detects chemicals that come into contact with the tongue
What we experience as taste is actually more about smell than taste
Taste receptor cells, gustatory cells, are clustered in papillae on the tongue
Receptors are sensitive to five basic taste qualities: Sweetness, Saltiness,
Sourness, Bitterness, Umami—glutamates {Given the complexities and recent
discovery of umami, its classification as a fifth taste quality is a source of current
debate (for an overview of umami research, see Beauchamp, 2009)}.

92. TOUCH
(CUTANEOUS SYSTEM)

93. TOUCH
(CUTANEOUS SYSTEM)
Part of a larger sensory system known as the somatic senses
which provides the brain with information about the body,
its condition, and the body’s relationship with the outside
world

94. TOUCH
(CUTANEOUS SYSTEM)
Part of a larger sensory system known as the somatic senses
which provides the brain with information about the body,
its condition, and the body’s relationship with the outside
world
Cutaneous receptors respond to pressure, shape, texture,
movement, and temperature

95. TOUCH
(CUTANEOUS SYSTEM)
Part of a larger sensory system known as the somatic senses
which provides the brain with information about the body,
its condition, and the body’s relationship with the outside
world
Cutaneous receptors respond to pressure, shape, texture,
movement, and temperature
Nociceptors extend from the spinal cord to the body and are
involved in the experience of pain

97. HOW DOES TOUCH
WORK?

98. HOW DOES TOUCH
WORK?
Kinesthesis: Communicates information about movement and location of body parts. Receptors are found
in joints and ligaments

99. HOW DOES TOUCH
WORK?
Kinesthesis: Communicates information about movement and location of body parts. Receptors are found
in joints and ligaments
Vestibular sense: This is also called equilibratory sense. Receptors are in semicircular canals and vestibular
sacs found in the inner ear. This is concerned with the sense of balance and knowledge of body position. The
vestibular organ monitors head movements and movements of the eyes. The semicircular canals are filled
with a jelly-like substance lined with hair cells.

100. HOW DOES TOUCH
WORK?
Kinesthesis: Communicates information about movement and location of body parts. Receptors are found
in joints and ligaments
Vestibular sense: This is also called equilibratory sense. Receptors are in semicircular canals and vestibular
sacs found in the inner ear. This is concerned with the sense of balance and knowledge of body position. The
vestibular organ monitors head movements and movements of the eyes. The semicircular canals are filled
with a jelly-like substance lined with hair cells.
Skin senses: Basic skin sensations include cold, warmth, pressure, and pain. Current research does not
support the belief that specialized receptor cells for each of the four skin sensations exist.

101. HOW DOES TOUCH
WORK?
Kinesthesis: Communicates information about movement and location of body parts. Receptors are found
in joints and ligaments
Vestibular sense: This is also called equilibratory sense. Receptors are in semicircular canals and vestibular
sacs found in the inner ear. This is concerned with the sense of balance and knowledge of body position. The
vestibular organ monitors head movements and movements of the eyes. The semicircular canals are filled
with a jelly-like substance lined with hair cells.
Skin senses: Basic skin sensations include cold, warmth, pressure, and pain. Current research does not
support the belief that specialized receptor cells for each of the four skin sensations exist.
Touch plasticity: When an area of the skin is used a lot, it becomes more sensitive, and the receptors
actually “take over” more brain space in the corresponding sensory region of the brain. Thus, when blind
people use their first two fingers for brail, it has been found that in the brain, the region of the cortex
devoted to these two fingers actually spreads and takes over less- used cortex from other touch areas. Thus,
physical experience changes the brain directly (this has broader connections for the influence of experience
on perceptual processing and thought).

102. HOW DOES TOUCH
WORK?
Kinesthesis: Communicates information about movement and location of body parts. Receptors are found
in joints and ligaments
Vestibular sense: This is also called equilibratory sense. Receptors are in semicircular canals and vestibular
sacs found in the inner ear. This is concerned with the sense of balance and knowledge of body position. The
vestibular organ monitors head movements and movements of the eyes. The semicircular canals are filled
with a jelly-like substance lined with hair cells.
Skin senses: Basic skin sensations include cold, warmth, pressure, and pain. Current research does not
support the belief that specialized receptor cells for each of the four skin sensations exist.
Touch plasticity: When an area of the skin is used a lot, it becomes more sensitive, and the receptors
actually “take over” more brain space in the corresponding sensory region of the brain. Thus, when blind
people use their first two fingers for brail, it has been found that in the brain, the region of the cortex
devoted to these two fingers actually spreads and takes over less- used cortex from other touch areas. Thus,
physical experience changes the brain directly (this has broader connections for the influence of experience
on perceptual processing and thought).
Pain

104. BASICS OF PAIN

105. BASICS OF PAIN
Pain is not triggered by one stimulus (e.g., as light does for vision), and at certain intensities other stimuli
can cause pain (e.g., coolness).

106. BASICS OF PAIN
Pain is not triggered by one stimulus (e.g., as light does for vision), and at certain intensities other stimuli
can cause pain (e.g., coolness).
Pain circuit: Sensory receptors respond to potentially damaging stimuli by sending an impulse to the spinal
cord, which sends the message to the brain, which interprets the signal as pain.

107. BASICS OF PAIN
Pain is not triggered by one stimulus (e.g., as light does for vision), and at certain intensities other stimuli
can cause pain (e.g., coolness).
Pain circuit: Sensory receptors respond to potentially damaging stimuli by sending an impulse to the spinal
cord, which sends the message to the brain, which interprets the signal as pain.
Thicker and faster axons convey sharp pain, and thinner ones convey dull pain. These axons enter the spinal
cord, where they release two neurotransmitters depending on the severity of the pain:

108. BASICS OF PAIN
Pain is not triggered by one stimulus (e.g., as light does for vision), and at certain intensities other stimuli
can cause pain (e.g., coolness).
Pain circuit: Sensory receptors respond to potentially damaging stimuli by sending an impulse to the spinal
cord, which sends the message to the brain, which interprets the signal as pain.
Thicker and faster axons convey sharp pain, and thinner ones convey dull pain. These axons enter the spinal
cord, where they release two neurotransmitters depending on the severity of the pain:
Mild pain releases glutamate. Severe pain releases both glutamate and Substance P, a neuromodulator.

109. BASICS OF PAIN
Pain is not triggered by one stimulus (e.g., as light does for vision), and at certain intensities other stimuli
can cause pain (e.g., coolness).
Pain circuit: Sensory receptors respond to potentially damaging stimuli by sending an impulse to the spinal
cord, which sends the message to the brain, which interprets the signal as pain.
Thicker and faster axons convey sharp pain, and thinner ones convey dull pain. These axons enter the spinal
cord, where they release two neurotransmitters depending on the severity of the pain:
Mild pain releases glutamate. Severe pain releases both glutamate and Substance P, a neuromodulator.
Pain receptors can also react to chemicals. For example, capsaicin is a chemical found in hot peppers that
stimulates pain receptors. Capsaicin also leads to insensitivity to pain.

110. BASICS OF PAIN
Pain is not triggered by one stimulus (e.g., as light does for vision), and at certain intensities other stimuli
can cause pain (e.g., coolness).
Pain circuit: Sensory receptors respond to potentially damaging stimuli by sending an impulse to the spinal
cord, which sends the message to the brain, which interprets the signal as pain.
Thicker and faster axons convey sharp pain, and thinner ones convey dull pain. These axons enter the spinal
cord, where they release two neurotransmitters depending on the severity of the pain:
Mild pain releases glutamate. Severe pain releases both glutamate and Substance P, a neuromodulator.
Pain receptors can also react to chemicals. For example, capsaicin is a chemical found in hot peppers that
stimulates pain receptors. Capsaicin also leads to insensitivity to pain.
Pain relief: Endorphins block the release of Substance P in the spinal cord and brain stem.

111. BASICS OF PAIN
Pain is not triggered by one stimulus (e.g., as light does for vision), and at certain intensities other stimuli
can cause pain (e.g., coolness).
Pain circuit: Sensory receptors respond to potentially damaging stimuli by sending an impulse to the spinal
cord, which sends the message to the brain, which interprets the signal as pain.
Thicker and faster axons convey sharp pain, and thinner ones convey dull pain. These axons enter the spinal
cord, where they release two neurotransmitters depending on the severity of the pain:
Mild pain releases glutamate. Severe pain releases both glutamate and Substance P, a neuromodulator.
Pain receptors can also react to chemicals. For example, capsaicin is a chemical found in hot peppers that
stimulates pain receptors. Capsaicin also leads to insensitivity to pain.
Pain relief: Endorphins block the release of Substance P in the spinal cord and brain stem.
Gate control theory of pain: The brain can only focus on one pain stimulus at a time. For example, athletes
are so focused on the competition that they often are unaware of any injuries until after they have finished
competing.

112. BASICS OF PAIN
Pain is not triggered by one stimulus (e.g., as light does for vision), and at certain intensities other stimuli
can cause pain (e.g., coolness).
Pain circuit: Sensory receptors respond to potentially damaging stimuli by sending an impulse to the spinal
cord, which sends the message to the brain, which interprets the signal as pain.
Thicker and faster axons convey sharp pain, and thinner ones convey dull pain. These axons enter the spinal
cord, where they release two neurotransmitters depending on the severity of the pain:
Mild pain releases glutamate. Severe pain releases both glutamate and Substance P, a neuromodulator.
Pain receptors can also react to chemicals. For example, capsaicin is a chemical found in hot peppers that
stimulates pain receptors. Capsaicin also leads to insensitivity to pain.
Pain relief: Endorphins block the release of Substance P in the spinal cord and brain stem.
Gate control theory of pain: The brain can only focus on one pain stimulus at a time. For example, athletes
are so focused on the competition that they often are unaware of any injuries until after they have finished
competing.
Phantom limb pain: The person feels pain in area of amputated limb. Phantom limb sensations suggest that
the brain can misinterpret spontaneous central nervous system activity that still occurs even when normal
sensory input (from limbs, eyes, nose, or skin) is not there. See Melzak (1992, 1993) and Ramachandran
(2007) if you’d like to learn more:)

114. PERCEPTION IS THE PROCESS OF SELECTING
AND IDENTIFYING INFORMATION FROM THE
ENVIRONMENT

115. PERCEPTION IS THE PROCESS OF SELECTING
AND IDENTIFYING INFORMATION FROM THE
ENVIRONMENT
Perception is the interpretation of information from the environment so that we can identify its meaning.

116. PERCEPTION IS THE PROCESS OF SELECTING
AND IDENTIFYING INFORMATION FROM THE
ENVIRONMENT
Perception is the interpretation of information from the environment so that we can identify its meaning.
Sensation usually involves sensing the existence of a stimulus, whereas perceptual systems involve the
determination of what a stimulus is.

117. PERCEPTION IS THE PROCESS OF SELECTING
AND IDENTIFYING INFORMATION FROM THE
ENVIRONMENT
Perception is the interpretation of information from the environment so that we can identify its meaning.
Sensation usually involves sensing the existence of a stimulus, whereas perceptual systems involve the
determination of what a stimulus is.
Expectations and perception: Our knowledge about the world allows us to make fairly accurate predictions
about what should be there—so we don’t need a lot of information from the stimulus itself.

118. PERCEPTION IS THE PROCESS OF SELECTING
AND IDENTIFYING INFORMATION FROM THE
ENVIRONMENT
Perception is the interpretation of information from the environment so that we can identify its meaning.
Sensation usually involves sensing the existence of a stimulus, whereas perceptual systems involve the
determination of what a stimulus is.
Expectations and perception: Our knowledge about the world allows us to make fairly accurate predictions
about what should be there—so we don’t need a lot of information from the stimulus itself.
Bottom-up processes are processes that are involved in identifying a stimulus by analyzing the information
available in the external stimulus. This also refers to information processing that begins at the receptor level
and continues to higher brain centers.

119. PERCEPTION IS THE PROCESS OF SELECTING
AND IDENTIFYING INFORMATION FROM THE
ENVIRONMENT
Perception is the interpretation of information from the environment so that we can identify its meaning.
Sensation usually involves sensing the existence of a stimulus, whereas perceptual systems involve the
determination of what a stimulus is.
Expectations and perception: Our knowledge about the world allows us to make fairly accurate predictions
about what should be there—so we don’t need a lot of information from the stimulus itself.
Bottom-up processes are processes that are involved in identifying a stimulus by analyzing the information
available in the external stimulus. This also refers to information processing that begins at the receptor level
and continues to higher brain centers.
Top-down processes are processes that are involved in identifying a stimulus by using the knowledge we
already possess about the situation. This knowledge is based on past experiences and allows us to form
expectations about what we ought to perceive.This also refers to information processing that begins in
higher brain centers and proceeds to receptors. b. Top-down processes allow for perceptual judgments and
bias to start influencing how we process incoming stimuli and information. Early incoming information is
already being processed in terms of top-down influences and previous experience.

121. PERCEPTION

122. PERCEPTION
A.K.A. the process through which we select, organize, interpret, and give
meaning to sensations

123. PERCEPTION
A.K.A. the process through which we select, organize, interpret, and give
meaning to sensations
Figure-ground perception and grouping are ways we begin to organize and
understand sensations

124. PERCEPTION
A.K.A. the process through which we select, organize, interpret, and give
meaning to sensations
Figure-ground perception and grouping are ways we begin to organize and
understand sensations
Perceptual selectivity describes reasons we select of some sensory inputs for
attention and ignore others

125. PERCEPTION
A.K.A. the process through which we select, organize, interpret, and give
meaning to sensations
Figure-ground perception and grouping are ways we begin to organize and
understand sensations
Perceptual selectivity describes reasons we select of some sensory inputs for
attention and ignore others
Stimulus factors are those characteristics of objects that affect our perception of
the object

126. PERCEPTION
A.K.A. the process through which we select, organize, interpret, and give
meaning to sensations
Figure-ground perception and grouping are ways we begin to organize and
understand sensations
Perceptual selectivity describes reasons we select of some sensory inputs for
attention and ignore others
Stimulus factors are those characteristics of objects that affect our perception of
the object
Personal factors including experience, values, expectations, context, and mental
and emotional states affect our perception

128. IMPORTANT TERMS

129. IMPORTANT TERMS
Photo receptors

130. IMPORTANT TERMS
Photo receptors
Chemoreceptors

131. IMPORTANT TERMS
Photo receptors
Chemoreceptors
Mechanoreceptors

132. IMPORTANT TERMS
Photo receptors
Chemoreceptors
Mechanoreceptors
Mechanoreceptors

133. IMPORTANT TERMS
Photo receptors
Chemoreceptors
Mechanoreceptors
Mechanoreceptors
Signal detection theory

134. IMPORTANT TERMS
Photo receptors
Chemoreceptors
Mechanoreceptors
Mechanoreceptors
Signal detection theory
Absolute threshold

135. IMPORTANT TERMS
Photo receptors
Chemoreceptors
Mechanoreceptors
Mechanoreceptors
Signal detection theory
Absolute threshold
Sensory adaptation

136. IMPORTANT TERMS
Photo receptors
Chemoreceptors
Mechanoreceptors
Mechanoreceptors
Signal detection theory
Absolute threshold
Sensory adaptation
Just noticeable difference

137. IMPORTANT TERMS
Photo receptors
Chemoreceptors
Mechanoreceptors
Mechanoreceptors
Signal detection theory
Absolute threshold
Sensory adaptation
Just noticeable difference
Weber’s Law

138. IMPORTANT TERMS
Photo receptors
Chemoreceptors
Mechanoreceptors
Mechanoreceptors
Signal detection theory
Absolute threshold
Sensory adaptation
Just noticeable difference
Weber’s Law
Visual system

139. IMPORTANT TERMS
Photo receptors
Chemoreceptors
Mechanoreceptors
Mechanoreceptors
Signal detection theory
Absolute threshold
Sensory adaptation
Just noticeable difference
Weber’s Law
Visual system
Trichromatic & Opponent-process theories of
color vision

140. IMPORTANT TERMS
Photo receptors
Chemoreceptors
Mechanoreceptors
Mechanoreceptors
Signal detection theory
Absolute threshold
Sensory adaptation
Just noticeable difference
Weber’s Law
Visual system
Trichromatic & Opponent-process theories of
color vision
Auditory system

141. IMPORTANT TERMS
Photo receptors
Chemoreceptors
Mechanoreceptors
Mechanoreceptors
Signal detection theory
Absolute threshold
Sensory adaptation
Just noticeable difference
Weber’s Law
Visual system
Trichromatic & Opponent-process theories of
color vision
Auditory system

142. IMPORTANT TERMS
Photo receptors Olfactory System
Chemoreceptors
Mechanoreceptors
Mechanoreceptors
Signal detection theory
Absolute threshold
Sensory adaptation
Just noticeable difference
Weber’s Law
Visual system
Trichromatic & Opponent-process theories of
color vision
Auditory system

143. IMPORTANT TERMS
Photo receptors Olfactory System
Chemoreceptors Gustatory system
Mechanoreceptors
Mechanoreceptors
Signal detection theory
Absolute threshold
Sensory adaptation
Just noticeable difference
Weber’s Law
Visual system
Trichromatic & Opponent-process theories of
color vision
Auditory system

144. IMPORTANT TERMS
Photo receptors Olfactory System
Chemoreceptors Gustatory system
Mechanoreceptors Cutaneous system
Mechanoreceptors
Signal detection theory
Absolute threshold
Sensory adaptation
Just noticeable difference
Weber’s Law
Visual system
Trichromatic & Opponent-process theories of
color vision
Auditory system

145. IMPORTANT TERMS
Photo receptors Olfactory System
Chemoreceptors Gustatory system
Mechanoreceptors Cutaneous system
Mechanoreceptors Proprioception system
Signal detection theory
Absolute threshold
Sensory adaptation
Just noticeable difference
Weber’s Law
Visual system
Trichromatic & Opponent-process theories of
color vision
Auditory system

146. IMPORTANT TERMS
Photo receptors Olfactory System
Chemoreceptors Gustatory system
Mechanoreceptors Cutaneous system
Mechanoreceptors Proprioception system
Signal detection theory Kinesthetic system
Absolute threshold
Sensory adaptation
Just noticeable difference
Weber’s Law
Visual system
Trichromatic & Opponent-process theories of
color vision
Auditory system

147. IMPORTANT TERMS
Photo receptors Olfactory System
Chemoreceptors Gustatory system
Mechanoreceptors Cutaneous system
Mechanoreceptors Proprioception system
Signal detection theory Kinesthetic system
Absolute threshold Vestibular system
Sensory adaptation
Just noticeable difference
Weber’s Law
Visual system
Trichromatic & Opponent-process theories of
color vision
Auditory system

148. IMPORTANT TERMS
Photo receptors Olfactory System
Chemoreceptors Gustatory system
Mechanoreceptors Cutaneous system
Mechanoreceptors Proprioception system
Signal detection theory Kinesthetic system
Absolute threshold Vestibular system
Sensory adaptation Perception
Just noticeable difference
Weber’s Law
Visual system
Trichromatic & Opponent-process theories of
color vision
Auditory system

149. IMPORTANT TERMS
Photo receptors Olfactory System
Chemoreceptors Gustatory system
Mechanoreceptors Cutaneous system
Mechanoreceptors Proprioception system
Signal detection theory Kinesthetic system
Absolute threshold Vestibular system
Sensory adaptation Perception
Just noticeable difference Top-down and bottom-up processing
Weber’s Law
Visual system
Trichromatic & Opponent-process theories of
color vision
Auditory system

150. IMPORTANT TERMS
Photo receptors Olfactory System
Chemoreceptors Gustatory system
Mechanoreceptors Cutaneous system
Mechanoreceptors Proprioception system
Signal detection theory Kinesthetic system
Absolute threshold Vestibular system
Sensory adaptation Perception
Just noticeable difference Top-down and bottom-up processing
Weber’s Law Gestalt
Visual system
Trichromatic & Opponent-process theories of
color vision
Auditory system

151. IMPORTANT TERMS
Photo receptors Olfactory System
Chemoreceptors Gustatory system
Mechanoreceptors Cutaneous system
Mechanoreceptors Proprioception system
Signal detection theory Kinesthetic system
Absolute threshold Vestibular system
Sensory adaptation Perception
Just noticeable difference Top-down and bottom-up processing
Weber’s Law Gestalt
Visual system Stimulus factors
Trichromatic & Opponent-process theories of
color vision
Auditory system

152. IMPORTANT TERMS
Photo receptors Olfactory System
Chemoreceptors Gustatory system
Mechanoreceptors Cutaneous system
Mechanoreceptors Proprioception system
Signal detection theory Kinesthetic system
Absolute threshold Vestibular system
Sensory adaptation Perception
Just noticeable difference Top-down and bottom-up processing
Weber’s Law Gestalt
Visual system Stimulus factors
Trichromatic & Opponent-process theories of Personal factors
color vision
Auditory system

153. IMPORTANT TERMS
Photo receptors Olfactory System
Chemoreceptors Gustatory system
Mechanoreceptors Cutaneous system
Mechanoreceptors Proprioception system
Signal detection theory Kinesthetic system
Absolute threshold Vestibular system
Sensory adaptation Perception
Just noticeable difference Top-down and bottom-up processing
Weber’s Law Gestalt
Visual system Stimulus factors
Trichromatic & Opponent-process theories of Personal factors
color vision
Extrasensory perception and paranormal
Auditory system psychology