Transcript half a second before

Learning
How does experience affect
behaviors and/or attitudes?
By Association!!
• Our minds naturally
connect events that
occur in sequence.
– Affects Behaviors
By Association!!
• Our minds naturally
connect events that
occur in sequence.
– Affects Attitudes
Sovfoto
Pavlov and Classical Conditioning
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Classical Conditioning
• Unconditioned Stimulus (US)
– A stimulus (an event) that triggers an
unconditioned (involuntary) response.
• Examples: food, loud noises, painful stimuli, bursts of
air
Classical Conditioning
• Unconditioned response (UR)
– An unlearned response to an unconditioned
stimulus.
• Examples: hunger -> food, jumping ->horror flick,
blinking -> flying objects near eye
Classical Conditioning
• Conditioned stimulus (CS)
– A neutral stimulus (an event) that comes to evoke
a learned response due to being presented shortly
before the US.
• Ex: Bell ringing in high school, Fridays!!, Cologne
Classical Conditioning
• Conditioned response (CR)
– A learned response to a classically conditioned
stimulus (CS)
• Ex: Salivation of Pavlov’s dog just to the bell, your
mouth watering when you smell warm cookies, smiling
when you hear a song that reminds you of someone (or
frowning…depending)
CC Check
• Every time someone flushes a toilet in the
apartment building, the shower becomes very
hot and causes the person to jump back. Over
time, the person begins to jump back
automatically after hearing the flush, before the
water temperature changes.
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What is the:
UCS
UCR
Neutral Stimulus/CS
CR?
Acquisition
The initial stage in classical conditioning.
during which association between a neutral
stimulus and a US takes place.
1. Neutral stimulus needs to come before the
US for conditioning to occur (most cases).
2. The time between the two stimuli should be
about half a second.
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Acquisition
The CS needs to come half a second before
the US to cause acquisition.
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Extinction
When a US (food) does not follow a CS (tone)
CR (salivation) starts to decrease and at some
point goes extinct.
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Reinstatement
After a rest period an extinguished CR
(salivation) spontaneously recovers and if CS
(tone) persists alone becomes extinct again.
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Stimulus Generalization
Tendency to respond to
stimuli similar to CS is
called generalization.
• “Little Albert”
– Conditioned to fear a white
lab rat
– Fear generalized to anything
white and furry
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Stimulus Discrimination
Discrimination is the learned ability to
distinguish between a CS and other stimuli
that do not signal a US.
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Applications of Classical Conditioning
1. Alcoholics can be conditioned (aversively)
partly reversing their positive-associations
with alcohol.
2. A drug (plus its taste) that affects the
immune response, can lead the taste to
invoke the immune response through
classical conditioning.
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Operant Conditioning
Tilikum Attacks!!
Operant & Classical Conditioning
Classical conditioning
forms associations
between stimuli (CS
and US).
Operant conditioning on
the other hand forms
association between
behaviors and
resulting events.
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Operant Conditioning
• Cats in puzzle boxes
– Time to escape decreased with practice
– Thorndike’s “Law of Effect”
• Responses followed by positive outcomes are repeated,
whereas those followed by negative outcomes are not
Shaping
Operant conditioning procedure in which
reinforcers guide behavior closer towards target
behavior through successive approximations.
Method used in training schools
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Types of Reinforcers
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Primary & Secondary Reinforcers
1. Primary Reinforcer: Innately reinforcing
stimulus like food, drink, sex (depending).
2. Conditioned Reinforcer: Is a learned
reinforcer. It gets its reinforcing power
through its association with primary
reinforcer. Ex. Money, praise, good grades,
awards, gold stars
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Immediate & Delayed Reinforcers
1.
Immediate Reinforcer: A reinforcer that occurs
closely to a behavior in time. Rat gets a food
pellet for a bar press.
2.
Delayed Reinforcer: A reinforcer that is delayed
in time for a certain behavior. A paycheck that
comes at the end of a week.
We may be more inclined to engage in small immediate
reinforcers (watching TV) than large delayed reinforcers
(Getting A in a course) which requires consistent study.
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Reinforcement Schedules
1. Continuous Reinforcement: Reinforcing the
desired response each time it occurs.
2. Partial Reinforcement: Reinforcing a
response only part of the time. Though
results in slower acquisition in the
beginning, shows greater resistance to
extinction later on.
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Ratio Schedules
1. Fixed-ratio schedule:
Reinforces a response only
after a specified number of
responses e.g., like
piecework pay, “I’m going
to count to three.”
2. Variable-ratio schedule:
Reinforces a response after
an unpredictable number
of responses. Hard to
extinguish because of
unpredictability, e.g.,
behaviors like gambling,
fishing.
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Interval Schedules
1. Fixed-interval schedule: Reinforces a
response only after a specified time has
elapsed e.g., preparing for an exam only
when the exam draws close, getting a raise
every year and not in between.
2. Variable-interval schedule: Reinforces a
response at unpredictable time intervals.
produces slow steady responding, e.g.,
pop quiz, boss checking on you
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Punishment
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Motivation
Intrinsic Motivation:
The desire to perform a
behavior for its own
sake.
Extrinsic Motivation:
The desire to perform a
behavior due to
promised rewards or
threats of punishments.
How “rewarding” is it for an orca to leap in the
air for [already] dead fish from a bucket?
THIS is how orca’s feed:
http://www.youtube.com/watch?v=k5M3gs76fzA
http://www.youtube.com/watch?v=p3xmqbNsRSk
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Applications of Operant Conditioning
Skinner introduced the concept of teaching
machines that would shape learning in small
steps and provide reinforcements for correct
rewards.
LWA-JDL/ Corbis
In School
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Applications of Operant Conditioning
Reinforcement principles can enhance athletic
performance.
In Sports
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Applications of Operant Conditioning
Reinforcers affect productivity. Many companies
now enable employees to share profits and
participate in company ownership.
At work
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Operant Conditioning & Token Economy:
“Warden, I’ve been good…my cigarettes please!”
Person exchanges a token of
some sort, earned for
exhibiting the desired
behavior, for various
privileges or treats.
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This 14-month-old child
imitates the adult on TV
in pulling a toy apart.
Meltzoff, A.N. (1998). Imitation of televised models by infants.
Child Development, 59 1221-1229. Photos Courtesy of A.N. Meltzoff and M. Hanuk.
Imitation Onset-Learning via
Observation
Bandura's Bobo doll
study (1961) indicated
that individuals
(children) learn through
imitating others who
receive rewards and
punishments.
Courtesy of Albert Bandura, Stanford University
Bandura's Experiments
Negative Observational Learning
Bandura’s studies
show that antisocial
models (family,
neighborhood or TV)
may have antisocial
effects.
Positive Observational Learning
Bob Daemmrich/ The Image Works
Prosocial (positive, helpful) models may have
prosocial effects.
Gentile et al., (2004)
shows that children in
elementary school who
are exposed to violent
television, videos, and
video games express
increased aggression.
Ron Chapple/ Taxi/ Getty Images
Television and Observational
Learning
Modeling Violence
Children modeling after pro wrestlers
Glassman/ The Image Works
Bob Daemmrich/ The Image Works
Research shows that viewing media violence
leads to an increased expression of aggression.
Latent Learning
Such cognitive maps are based on latent
learning, which becomes apparent only when
an incentive is given (Tolman & Honzik, 1930).
Biological Predisposition
Photo: Bob Bailey
Biological constraints
predispose organisms to
learn associations that
are naturally adaptive.
Breland and Breland
(1961) showed that
animals drift towards
their biologically
predisposed instinctive
behaviors.
Marian Breland Bailey
Skinner’s Legacy
Skinner argued that behaviors were shaped by
external influences instead of inner thoughts and
feelings. Critics argued that Skinner
dehumanized people by neglecting their free will.
Falk/ Photo Researchers, Inc
.
Motivation
Motivation is a need or
desire that energizes
behavior and directs it
towards a goal.
Aron Ralston
AP Photo/ Rocky Mountain News, Judy Walgren
Aron Ralston was
motivated to cut his
arm in order to free
himself from a rock
that pinned him
down.
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Perspectives on Motivation
Four perspectives used to explain motivation
include the following:
1. Instinct Theory (replaced
by the evolutionary
perspective)
2. Drive-Reduction Theory
3. Arousal Theory
4. Hierarchy of Motives
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Instincts & Evolutionary Psychology
Instincts are complex behaviors that have fixed
patterns throughout different species and are not
learned (Tinbergen, 1951).
Tony Brandenburg/ Bruce Coleman, Inc.
© Ariel Skelley/ Masterfile
Where the woman builds different kinds of houses
the bird builds only one kind of nest.
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Drives and Incentives
When the instinct theory of motivation failed, it
was replaced by the drive-reduction theory. A
physiological need creates an aroused tension
state (a drive) that motivates an organism to
satisfy the need.
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Incentive
Where our needs push, incentives (positive or
negative stimuli) pull us in reducing our drives.
A food-deprived person who smells baking bread
(incentive) feels a strong hunger drive.
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Optimum Arousal
Human motivation aims to seek optimum levels
of arousal, not to eliminate it. Young monkeys
and children are known to explore the
environment in the absence of a need-based
drive.
Randy Faris/ Corbis
Harlow Primate Laboratory, University of Wisconsin
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A Hierarchy of Motives
Abraham Maslow (1970)
suggested that certain
needs have priority over
others. Physiological
needs like breathing,
thirst, and hunger come
before psychological
needs such as
achievement, self-esteem,
and the need for
recognition.
(1908-1970)
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Hierarchy of Needs
Joe Skipper/ Reuters/ Corbis
Mario Tama/ Getty Images
David Portnoy/ Getty Images for Stern
Menahem Kahana/ AFP/ Getty Images
Hurricane Survivors
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Hunger
When do we eat?
When we are hungry.
When are we hungry?
When there is no food in our stomach.
How do we know when our stomach is empty?
Our stomach growls. These are also called
hunger pangs.
The Physiology of Hunger
Stomach contractions (pangs) send signals to
the brain making us aware of our hunger.
Stomachs Removed
Tsang (1938) removed rat stomachs, connected the
esophagus to the small intestines, and the rats still
felt hungry (and ate food).
Body Chemistry & the Brain
Levels of glucose in
the blood are
monitored by
receptors (neurons) in
the stomach, liver, and
intestines. They send
signals to the
hypothalamus in the
brain.
Rat Hypothalamus
Hypothalamic Centers
The lateral hypothalamus (LH) brings on hunger
(stimulation). Destroy the LH, and the animal has
no interest in eating. The reduction of blood
glucose stimulates orexin in the LH, which leads
rats to eat ravenously.
Hypothalamic Centers
The ventromedial hypothalamus (VMH)
depresses hunger (stimulation). Destroy the VMH,
and the animal eats excessively.
Richard Howard
Hypothalamus & Hormones
The hypothalamus monitors a number of hormones that
are related to hunger.
Hormone
Orexin increase
Tissue
Response
Hypothalamus Increases hunger
Ghrelin increase Stomach
Increases hunger
Insulin increase
Pancreas
Increases hunger
Leptin increase
Fat cells
Decreases hunger
PPY increase
Digestive tract
Decreases hunger