CHAPTER 4
I. Sensation and Perception
A. Sensation: the stimulation of sensory receptors and the transmission of
sensory information to the central nervous system.
B. Perception: an active process in which sensations are organized and
interpreted to form an inner representation of the world.
1. Begins with sensation but also reflects our experiences and
expectations as it makes sense of sensory stimuli.
C. Five senses: vision, hearing, smell, taste, and touch. Plus others?
D. Concepts that apply to sensation include absolute threshold, difference
threshold, signal-detection theory, and sensory adaptation.
E. Absolute threshold
1. Fechner founded a discipline known as psychophysics that focuses on
ways in which we translate physical events such as light and sounds
into psychological experiences.
2. Absolute threshold: refers to the weakest amount of a stimulus that a
person can distinguish from no stimulus at all 50% of the time.
a. Vision: a candle flame viewed from about 30 miles on a clear, dark
night.
b. Hearing: a watch ticking from about 20 feet away in a quiet room.
c. Taste: 1 teaspoon of sugar dissolved in 2 gallons of water.
d. Smell: about one drop of perfume diffused throughout a small
house (1 part in 500 million).
e. Touch: the pressure of the wing of a fly falling on a cheek from a
distance of about 0.4 inch.
F. Difference threshold: Is it the same, or is it different?
1. Difference threshold: the minimum difference in magnitude of two
stimuli required to tell them apart 50% of the time. Similar to the just
noticeable difference (jnd); when a person can detect the difference.
2. Weber found that for
a. light, the fraction is 1/60.
b. weight, the fraction is 1/53.
c. constant pitch, the fraction is 1/333.
G. Signal-detection theory considers the human aspects of sensation and
perception and also assumes that the relationship between a physical
stimulus and a sensory response is not just mechanical
1. Other factors:
a. Training (learning).
b. Motivation (desire to perceive).
c. Psychological states such as fatigue or alertness.
H. Feature detectors are brain cells that respond to different aspects of
features of a scene (e.g. angles, vertical, horizontal).
1. There are other types of detectors for the various senses; hearing has
pitch, loudness.
I. Sensory adaptation refers to the sensory process of adjustment.
1. It includes becoming more sensitive to stimuli of low magnitude and
less sensitive to stimuli that remain the same.
a. Becoming more sensitive to stimulation is referred to as
sensitization or positive adaptation.
b. Becoming less sensitive to stimulation is referred to as
desensitization or negative adaptation.
II. Vision
A. Light
1. Visible light triggers visual sensations.
2. All forms of electromagnetic energy moves in waves. Signature wave
lengths include the following:
a. Cosmic waves: wavelengths of these rays from outer space are
only a few trillionths of an inch long.
b. Radio waves: some radio signals extend for miles.
c. Visible light at about 400-billionths of a meter in length (violet) to
700-billionths of a meter (red).
d. Radio waves extend for miles.
e. Cosmic rays: wavelengths are only a few trillionths of an inch
long.
3. Sir Isaac Newton discovered the prism that could break light into
different colors.
a. Red, orange, yellow, green, blue, indigo, violet.
b. (Roy G. Biv)
c. The wavelength of visible light determines the color or hue.
i. The wavelength for red is longer than the wavelength for
orange and so on through the spectrum.
B. The Eye
1. Light first passes through the transparent cornea.
2. The amount of light that is allowed to enter is controlled by the muscle
called the iris (the colored part of the eye).
3. The actual opening in the iris is called the pupil.
a. Adjusts depending on the amount of light present; the more intense
the light, the smaller the opening.
b. Pupil size is also sensitive to emotions.
4. After the light passes through the iris, it encounters the lens.
a. The lens adjusts or accommodates to the image by changing its
thickness. The thickness permits a clear image of the object to be
projected onto the retina.
5. The retina consists of cells called photoreceptors that are sensitive to
light (photosensitive). There are two types of photoreceptors: rods and
cones.
a. The retina contains several layers of cells; the rods and cones,
bipolar cells, and ganglion cells. All of these are neurons.
i. The rods and cones respond to light with chemical changes that
create neural impulses that are picked up by the bipolar cells.
These then activate the ganglion cells.
ii. The axons of the million or so ganglion cells in our retina
ultimately converge to form the optic nerve.
iii. The optic nerve conducts sensory input to the brain where it is
relayed to the visual area of the occipital lobe.
6. Rods and cones are the photoreceptors in the retina.
a. About 125 million rods and 6.4 million cones are distributed across
the retina.
i. Cones are most densely packed in a small spot at the center of
the retina called the fovea.
ii. Visual acuity (sharpness and detail) is greatest at this spot.
iii. Rods are most dense just outside the fovea toward the
periphery of the retina.
b. Rods allow us to see in black and white.
c. Cones provide color vision.
d. In contrast to visual acuity is the blind spot, which is insensitive to
visual stimulation.
i. This is the part of the optic nerve that leaves the eye (the
ganglion cell axons converge to form the optic nerve).
e. Visual acuity is sharpness of vision.
i. Nearsighted: people who have to be unusually close to a distant
object to discriminate its details.
ii. Farsighted: people who see distant objects clearly but have
difficulty focusing on nearby objects.
f. When a person is in his or her late 30s to mid 40s, the lenses start
to grow brittle, making it more difficult to accommodate to, or
focus on, nearby objects. This condition is called presbyopia.
7. Light adaptation is the eye’s reaction to light.
a. Dark adaptation: the process of adjusting to lower lighting
conditions.
b. Cones reach their maximum adaptation to darkness in about 10
minutes.
c. Rods are more sensitive to dim light and continue to adapt for 45
minutes or so.
d. Adaptation to brighter lighting takes place much more rapidly with
adaptation happening in a minute or so.
C. Color Vision
1. The wavelength of light determines its color or hue.
2. The value of color is its degree of lightness or darkness.
3. Saturation refers to how intense a color appears.
a. Complementary colors are the colors across from one another on
the color wheel:
i. Red-green.
ii. Blue-yellow.
iii. If the complementary colors are mixed, they dissolve into gray.
 (Remember we are mixing lights not pigments.)
iv. White pigments reflect all colors equally; black pigments
reflect very little light.
4. Afterimages are persistent sensations of color.
a. They are followed by perception of the complimentary color when
the first color is removed.
D. Theories of Color Vision
1. Our ability to perceive color depends on the eye’s transmission of
different messages to the brain when lights with different wavelengths
stimulate the cones in the retina.
2. There are two main theories of color vision.
a. Trichromatic theory:
i. Young found that he could create any color from the visible
spectrum by simply varying the intensities of three lights: red,
green, and blue-violet.
ii. Helmholtz suggested that the retina in the eye must have three
different types of color photoreceptors or cones.
iii. The trichromatic theory is known as the Young-Helmholtz
theory.
b. Opponent-process theory:
i. Hering proposed that there are three types of color receptors,
but they don’t respond just to red, green, and blue-violet.
ii. They are pairs, including red-green, blue-yellow, and a type
that perceives differences in brightness.
iii. These pairs of receptors are what make afterimages possible
because they cannot transmit both of the opposing colors at the
same time.
iv. Research suggests that each theory of color vision is partially
correct. The cones may be as Helmholtz claimed; the
transmission of the signals to the brain are as Hering proposed
(through the bipolar and ganglion cells).
E. Color Blindness
1. If you can discriminate among the colors of the visible spectrum, you
have normal color vision and are labeled a trichromat.
a. This means that a person is sensitive to red-green, blue-yellow, and
light-dark.
2. People who are totally color blind are called monochromats.
a. They are sensitive to light-dark only.
3. Partial color blindness is a sex-linked trait that affects mostly males.
Partially color-blind people are called dichromats as they can
discriminate only among two colors (red and green or blue and yellow)
and the colors derived from mixing these colors.
III. Visual Perception
A. Sensory Impressions
1. Caused by the light that strikes our eyes.
2. Visual perception involves our knowledge, expectations, and
motivations.
3. Visual perception is an active process through which we interpret the
world around us.
a. This reflects the principle of closure.
B. Perceptual Organization
1. Gestalt psychologists are interested in the way we integrate bits and
pieces of sensory stimulation into meaningful wholes.
2. Figure-ground perception examples include the Rubin vase or the
Necker cube.
a. When figure-ground relationships are ambiguous, or capable of
being interpreted in various ways, our perceptions tend to be
unstable, shifting back and forth.
3. Other Gestalt rules for organization include proximity, similarity,
continuity, and common fate.
a. Proximity: nearness.
b. Similarity: we perceive similar objects as belonging together.
c. Continuity: we perceive a series of points or a broken line as
having unity.
d. Common fate: elements seen as moving together are perceived as
belonging together.
C. Perception of Motion
1. The visual perception of movement is based on a change of position
relative to other objects.
2. Psychologists have studied several types of apparent movement
(illusions of movement), one of which is stroboscopic motion.
a. Stoboscopic motion is what makes motion pictures possible.
i. The illusion of movement is provided by the presentation of a
rapid progression of images of stationary objects.
ii. Typically done by showing 16-22 frames per second.
D. Depth Perception
1. Monocular and binocular cues both help us perceive the depth of
objects.
a. Monocular cues: can be perceived by one eye, including
perspective, relative size, clearness, interposition, shadows, and
texture gradients.
b. Perspective: distances between far-off objects appear to be smaller
than equivalent distances between nearby objects.
c. Relative size: the fact that distant objects look smaller than nearby
objects of the same size.
d. Clearness of an object: we sense more details of nearby objects.
e. Overlapping: nearby objects can block our view of more distant
objects. Interposition is placing of one object in front of another.
f. Shadowing: opaque objects block light and produce shadows,
giving us a relationship to the source of light.
g. Texture gradient: close objects are perceived as having rougher
textures.
h. Motion parallax: the tendency of objects to seem to move
backward or forward as a function of their distance.
2. Binocular cues: involve both eyes and include retinal disparity and
convergence.
a. Retinal disparity: the difference between projected images (e.g.
different angles).
i. Closer objects have greater retinal disparity.
b. Convergence: causes feelings of tension in the eye muscles and
provides another binocular cue for depth.
E. Visual Illusions
1. Illusions often named after the people who devised them.
a. Hering-Helmholtz (horizontal lines with radiating lines).
b. Muller-Lyer (two lines, same length with arrowheads).
IV. Hearing
A. Waves
1. The changes in air pressure are vibrations that approach your ears in
waves.
a. The human ear is sensitive to sound waves with frequencies from
20 to 20,000 cycles per second.
B. Pitch and Loudness
1. Pitch and loudness are two psychological dimensions of sound.
a. The pitch of a sound is determined by its frequency, or the number
of cycles per second as expressed in the unit hertz (Hz).
i. The greater the number of cycles per second, the higher the
pitch of the sound.
b. The loudness of a sound roughly corresponds to the height or
amplitude of sound waves and is expressed in decibels (dB).
i. 25 dB is equivalent in loudness to a whisper at 5 feet.
ii. 30 dB is equivalent in loudness to what your librarian would
like at your college library.
iii. 85-90 dB means a person may experience hearing damage with
prolonged exposure.
c. People should use iPods for no more than 60 minutes a day at no
more than 60% of full volume (the “60-60 rule”) in order to avoid
hearing loss.
C. The Ear
1. The ear has three parts: the outer, middle, and inner ear.
2. The outer ear is shaped to funnel sound waves to the eardrum.
a. The eardrum is a thin membrane that vibrates in response to sound
waves and thereby transmits them to the middle and inner ears.
3. The middle ear contains the eardrum and three small bones: the
hammer, the anvil, and the stirrup. The middle ear functions as an
amplifier.
a. The stirrup is attached to another vibrating membrane, the oval
window. The oval window transmits vibrations into the inner ear to
a bony tube called the cochlea.
b. The cochlea is a snail-shaped structure that contains longitudinal
membranes that divide into three fluid-filled chambers. One of the
membranes that lie within the cochlea is the basilar membrane.
c. Attached to the basilar membrane is the organ of Corti, sometimes
referred to as the command post of hearing. Here, there are 25,000
receptor cells called hair cells.
d. Hair cells dance in response to the vibrations of the basilar
membrane. Their up and down movements generate neural
impulses that are transmitted to the brain via the auditory nerve.
e. Auditory input is then projected onto the hearing areas of the
temporal lobes of the cerebral cortex.
D. Locating Sounds
1. A sound that is louder in the right ear is perceived as coming from the
right.
2. Both loudness and the sequence in which the sounds reach the ears
provide directional cues.
E. Perception of Loudness and Pitch
1. The loudness and pitch of sounds appear to be related to the number of
receptor neurons on the organ of Corti that fire and how often they
fire.
2. Psychologists generally agree that sounds are perceived as louder
when more of these sensory neurons fire.
3. Three theories attempt to explain hearing.
a. Place theory: holds that the pitch of a sound is sensed according to
the place along the basilar membrane that vibrates in response to it.
b. Frequency theory: notes that for us to perceive lower pitches, we
need the stimulation of neural impulses that match the frequency of
the sound waves.
c. The volley principle: alternate firing of groups of neurons accounts
for pitch discrimination between a few hundred and 4,000 cycles
per second
F. Deafness
1. More than 1 in 10 Americans has a hearing impairment, and 1 in 100
cannot hear at all.
2. Two major types of deafness are conductive and sensorineural
deafness.
a. Conductive deafness: stems from damage to the structures of the
middle ear.
i. This is the hearing impairment often found among older
people.
ii. Hearing aids often help these people.
b. Sensorineural deafness usually stems from damage to the
structures of the inner ear, most often the loss of hair cells, which
normally do not regenerate.
i. The ringing sensation that often follows exposure to loud
noises probably means that hair cells have been damaged.
ii. Hair cells often do not regenerate.
iii. Individuals become sensitive to some sounds and not others.
iv. Cochlear implant can assist individuals with this type of
damage by bypassing the damaged cells, directly stimulating
the auditory nerve.
CHAPTER 5
I. Learning, Experience, and Change
A. Learning as defined by psychology is a relatively permanent change in behavior
that arises from practice or experience.
1. The behaviorist perspective plays down the roles of cognition and choice.
2. Cognitive psychologists define learning as the process by which organisms
make relatively permanent changes in the way they represent the environment
because of experience.
II. Classical Conditioning: Learning What Is Linked to What
A. Classical conditioning is a simple form of associative learning in which organisms
come to anticipate or associate events with one another.
B. Ivan Pavlov discovered classical conditioning.
1. Was studying salivation in dogs and accidently discovered classical
conditioning.
2. Reflexes: simple automatic responses to stimuli, which are unlearned.
3. Stimulus: an environmental condition that evokes a response from an
organism.
4. Pavlov discovered that reflexes can also be learned through association or the
repeated pairing of stimuli.
5. These learned reflexes are referred to as conditioned responses (CRs).
C. Why did Pavlov’s dogs learn to salivate in response to the tone?
1. Organisms form associations between stimuli because the stimuli are
contiguous—that is, they occur at about the same time.
2. They also learn because the stimuli are paired repeatedly.
3. Cognitive psychologists view classical conditioning as the learning of
relationships among events.
a. The focus is on the information gained by the organism, which is not how
the behaviorists see it (stimulus leads to response).
D. Stimuli and responses in classical conditioning are unlearned
1. Unconditioned stimulus (UCS) is unlearned: Pavlov’s meat powder elicits
salivation, an unconditioned response (UCR).
2. Orienting reflex: in this case, an automatic response where the dogs had to
look in the direction of the sound (a new and novel stimulus).
E.
F.
G.
H.
3. When the dogs learned to salivate to the sound of a bell (previously neutral),
the bell became the conditioned stimulus (CS) and the salivation in response
to the bell a conditioned response (CR).
Taste aversions are examples of classical conditioning.
1. Taste aversions are adaptive to organisms as they motivate them to avoid
potentially harmful food.
a. Different than classical conditioning.
i. Only one association may be required.
ii. The UCS and CS do not have to be contiguous.
2. The evolution of taste aversion suggests that animals and humans would be
biologically predisposed to develop aversions that are adaptive in their
environmental settings thus ensuring survival.
Extinction and spontaneous recovery
1. Extinction: the process by which a CS loses the ability to elicit CRs because
the CS is no longer paired with the UCS.
2. Spontaneous recovery: recovery of a CR after extinction. A function of the
passage of time. The response is still there, just waiting for the right “time.”
a. Spontaneous recovery, like extinction, is adaptive.
Generalization and discrimination
1. Generalization is the tendency for a conditioned response to be evoked by
stimuli similar to the stimulus to which the response was conditioned.
2. Discrimination: organisms must learn.
a. Many stimuli perceived as being similar are functionally different.
b. The organism must respond adaptively to each.
Higher-order conditioning
1. In higher-order conditioning, a previously neutral stimulus serves as a learned
or CS after being paired repeatedly with a stimulus that has already become
learned.
2. Pavlov did this by getting the dogs to salivate to the shining of a light paired
with the tone.
3. Applications of classical conditioning
4. “Little Albert”: a child conditioned to fear a rat, demonstrating that fears can
be acquired through the principles of classical conditioning.
5. Humans may be biologically prepared by evolutionary forces to rapidly
develop fears of certain animals or other environmental cues that could do
them harm.
6. Counterconditioning is used to reduce fears by introducing pleasant
experiences instead of negative in the pairing, thus the initial response is
extinguished.
7. Flooding and systematic desensitization
a. Flooding is exposing the client with the feared object until the fear
response is extinguished.
b. Systematic desensitization is gradually exposing the client to the feared
object under circumstances where the client remains relaxed.
III. Operant Conditioning: Learning What Does What to What
A. Edward L. Thorndike and the Law of Effect
1. Thorndike put cats in a “puzzle box” in which they had to learn to pull a string
in order to get food.
2. His law of effect says that a response would be strengthened in a particular
situation by a reward, but punishment would “stamp out” the response.
B. Burrhus Frederic Skinner (1904-1990) and Reinforcement
1. Historical contributions: Skinner believed that pigeons could be trained to
guide missiles to their targets. The project, for the military, ended up being
scrapped; the pigeon equipment was too bulky.
2. Organisms learn to do something because of the effects or consequences of
that behavior.
3. Operant behavior is behavior that operates on or manipulates the environment.
4. Operant conditioning is a simple form of learning in which an organism learns
to engage in certain behavior because of the effects of that behavior.
C. Methods of Operant Conditioning
1. Focus on what people (organisms) do.
2. Skinner devised an operant chamber (Skinner box); a cage for animals used to
study operant conditioning. The chambers had a lever that the animals could
press to obtain reinforcements and a turning drum or cumulative recorder to
measure behavior (lever presses).
3. It matters little how the first response that is reinforced is made. It could be
random or guided.
a. People can be verbally guided into the desired response.
D. Types of Reinforcers
1. Any stimulus that increases the probability that responses preceding it will be
repeated serves as a reinforcer.
2. Positive reinforcers: increase the probability that the behavior will occur when
they are applied (ex: food and approval).
3. Negative reinforcers: increase the probability of a behavior when the
reinforcer is removed (ex: planning ahead so you don’t have to fear that things
will go wrong).
4. Immediate reinforcers are more effective than delayed reinforcers.
a. Short-term consequences often provide better incentive than long-term
consequences.
5. Primary reinforcers are effective because of an organism’s biological makeup
(e.g. food and water).
a. Secondary reinforcers acquire their value by being associated with
established reinforcers. Sometimes called conditioned reinforcers.
E. Extinction and Spontaneous Recovery in Operant Conditioning
1. Extinction occurs as a result of repeated performance of operant behavior
without reinforcement.
2. Spontaneous recovery occurs in operant conditioning. The reward returns and
the behavior increases.
F. Reinforcers versus Rewards and Punishments
1. Reinforcers are known by their effects: if the frequency of the behavior
increases, then the behavior was reinforced.
2. Rewards and punishments are known by how they feel.
3. Punishments are aversive events that suppress or decrease the frequency of
behavior they follow.
a. Positive punishment is the application of an aversive stimulus to decrease
unwanted behavior.
b. Negative punishment is the removal of a pleasant stimulus to decrease
unwanted behavior.
4. Discriminative stimuli act as cues by providing information about when an
operant will be reinforced.
a. Behaviors that are not reinforced will be extinguished.
b. Behaviors that are engaged in after the discriminative stimulus will be
reinforced and continued.
G. Schedules of Reinforcement
1. Some responses are maintained by means of continuous reinforcement;
reinforcement after every response. New behaviors are acquired more rapidly
through continuous reinforcement.
2. Partial reinforcement can also maintain behavior or reinforce it part of the
time.
a. Behavior is more resistant to extinction when partial reinforcement is
used.
3. Interval schedules vary.
a. Fixed interval: a fixed amount of time must elapse between the previous
and subsequent times when reinforcement occurs.
b. Variable interval: a variable amount of time occurs between
reinforcements.
4. Ratio schedules also vary.
a. Fixed ratio: reinforcement is provided after a fixed number of correct
responses have been made.
b. Variable ratio: reinforcement is provided after a variable number of
correct responses.
c. Both ratio schedules maintain high rates of responding.
H. Shaping
1. Shaping reinforces progressive steps toward the behavioral goal.
a. Reinforce successive approximations of the goal getting closer to the
desired behavior.
I. Applications of Operant Conditioning
1. Biofeedback training is based on the principles of operant conditioning.
a. Organisms can gain control over autonomic functions.
2. Behavior modification in the classroom involves accentuating the positive.
a. Ironic conditioning of undesirable behavior sometimes happens, this needs
to change.
b. Using peer approval as reinforcement.
c. Time out.
3. Programmed learning is a step-by-step process.
a. Complex tasks can be broken down into a number of smaller steps.
IV. Cognitive Factors in Learning
A. Terms
1. Cognitive psychologists use concepts such as mental structures, schemas,
templates, and information processing.
B. Latent Learning: Forming Cognitive Maps
1. Tolman showed that rats learn about their environment in the absence of
reinforcement.
a. This knowledge can be used later.
i. Learning might remain hidden or latent until motivated to behave.
ii. Distinguish between learning and performance.
C. Contingency Theory
1. Contingency theory: suggests that learning occurs only when the conditioned
stimulus provides information about the unconditioned stimulus.
2. Rescorla concluded that the co-appearance of two events cannot in itself
explain classical conditioning. Instead, learning occurs only when the
conditioned stimulus provides information about the unconditioned stimulus.
3. Learning theory occurs because a conditioned stimulus indicates that the
unconditioned stimulus is likely to follow.
D. Observational Learning
1. Albert Bandura proposed that we can acquire operants by observing the
behavior of others not actually experiencing the event.
a. Some of this learning can be exhibited immediately; some may be
dormant.
b. A person who engages in a response to be imitated is a model.
c. Observers are said to be vicariously reinforced.
2. Mirror neurons lead us to automatically imitate the behaviors of others. They
fire when an animal observes the behavior of another, and they stimulate
imitative behavior.
E. Violence in the Media and Aggression
1. Statistics
a. If a child watches 2 to 4 hours of TV a day, he will have seen 8,000
murders and 100,000 acts of violence by the time he finishes elementary
school.
b. Even G-rated movies, on average, have scenes of violence lasting 9-10
minutes per film.
2. Bandura: Effects of Violence in the Media
a. Bandura, Ross, and Ross (1963) conducted a study using a Bobo doll.
They found that children who had observed the aggressive model showed
significantly more aggressive behavior toward the doll themselves.
b. Violence is often shown to have only temporary or minimal effects if at
all.
3. Consensus on the Effects of Violence in the Media
a. Observational learning: children learn from observation.
b. Disinhibition: punishment inhibits behavior.
c. Increased arousal: likely to be aggressive when aroused.
d. Priming of aggressive thoughts and memories.
e. Habituation: we become habituated to repeated stimuli, decreasing
sensitivity.
f. May lead to real-life violence, especially when viewers can identify more
with the characters and when the violence is realistic.
g. Playing violent video games increases aggressive thoughts and behavior.
i. Males are more likely than females to act aggressively after playing
violent video games.
4. Additional Effects
a. There tends to be a circular relationship between exposure to media
violence and aggressive behavior, feeding each other.
b. Family constellations may also contribute to the imitation of violence:
i. Parental substance abuse.
ii. Paternal physical punishments.
iii. Single motherhood.
iv. Parental rejection.
v. If children believe that violence is inappropriate for them, they will be
less likely to act aggressively.