Transcript Chap2Alt

PSY 402
Theories of Learning
Chapter 2 – Learning and Adaptation
Learning Enables Adaptation
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The ability to adapt to one’s environment with
experience enhances survival.
Those organisms able to adapt were more
likely to survive and thus were selected by
natural selection.
Example of survival value of a behavior:
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Black-headed gulls and eggshells
Kittiwakes who nest on cliffs don’t remove shells
Fixed Action Patterns
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Fixed behavior sequences that are released by
an environment signal.
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Triggered by a releaser, also called a sign
stimulus
Not learned – built in to the genes, innate
Stereotyped – occur the same way each time and
in each person or organism
Eibl-Eibesfeldt considered smiling & eyebrow
flashing to be a human fixed action pattern.
Modification of Innate Behaviors
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Even behaviors that are innate can be
modified through conditioning.
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Gull chicks get better at pecking at their parents’
beaks to get food – more accurate.
Conditioning experiences can change
sensitivity to releasing signs.
Conditioning fine tunes the response to the
environment and enhances survival.
Acquired Changes in Response
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Habituation – response to a repeated stimulus
decreases with non-threat experience.
Sensitization – response to a variety of stimuli
increases with a single threat experience.
Examples:
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Ingestional neophobia, fear of new food
Rats orient less toward light, startle decreases
Chicks are less frightened by shadows flying
overhead with repeated exposure.
Instrumental Adaptation
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Instrumental learning (S-R) occurs when a
voluntary behavior (R) becomes associated
with a stimulus (S) because of its effect.
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Consequences can be either rewards or
punishments.
Rewards and punishments are defined by their
effect on behavior.
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A reward increases behavior
A punishment decreases behavior.
Reinforcement
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Reinforcement occurs when the association
between a stimulus and a response to it is
strengthened.
Positive reinforcement occurs when a
behavior is rewarded.
Negative reinforcement occurs when a
behavior results in avoidance or escape from a
bad consequence.
Shaping
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How can a behavior be reinforced if it never
occurs naturally (or accidentally)?
Shaping is a process where a complex or
unnatural behavior is learned as a series of
steps that are successively rewarded.
By rewarding successive approximations to
the desired behavior, eventually the target
behavior is learned.
Classical Conditioning Adaptation
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Organisms learn to recognize and respond
selectively to the signals that are important in
their environment.
Cues associated with food evoke digestion:
salivation, gastric juices, insulin secretion.
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Taste aversion learning – illness makes us avoid
foods that were eaten just prior to feeling sick.
Food preferences are associated with nutrients.
Examples of Conditioning
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Popcorn at the movies.
Fear of flying -- stronger with more
turbulence (a stronger UCS).
An antelope shying away from low tree
branches.
Nausea at the smell of alcohol after a
hangover.
Territoriality
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Environmental cues can become associated
with sexual rival males in gourami fish.
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Pairing the light with the rival signaled the other
fish to prepare so it was able to be more
aggressive.
Presenting the light without pairing it with the
rival had no effect.
Courtship behavior can also be conditioned,
leading to more successful nestbuilding, etc.
Fear Conditioning
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Freezing is a universal response to threat.
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Animals that freeze are less likely to be attacked.
Fear is an anticipatory pain response.
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It occurs in response to stimuli that have been
aversive in the past and motivates escape or
avoidance behaviors.
Fear also releases endorphins in rats who are
confronted by the smell or sight of a cat.
Conditioning and Addictions
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Drugs can be associated with environmental
cues present when the drugs are taken.
Instead of the drug response being
conditioned, an opposite adaptive response is
conditioned that lessens the drug’s effect.
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This is called drug tolerance.
Taking a drug under novel circumstances can
produce a drug overdose because the
compensatory effect is not present (no cues).
Sign Tracking (Auto-Shaping)
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Sign tracking occurs when a stimulus (cue) in
the environment is associated with reward or
punishment.
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The sign stimulus motivates approach or
avoidance behavior because of what it signals.
Negative sign tracking occurs when a sign
motivates withdrawal instead of approach.
Some signs signal safety because they mean a
bad thing is less likely to occur.
Extinction
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Associations are learned when they enhance
survival, but conditioning decreases when the
expected consequence no longer occurs.
Extinction occurs with both instrumental and
classical conditioning.
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Spontaneous recovery occurs after extinction has
been learned, but a break in exposure to the
stimulus occurs.
After spontaneous recovery, extinction returns.
Timing of Stimuli
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The strength of both instrumental and
classical conditioning depends on the timing
of events.
Reward or punishment must immediately
follow the emitted response in order to
strongly affect behavior.
Two stimuli must occur close together in time
in order for them to be associated with each
other.
Size of the Stimuli
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The strength of both instrumental and
classical conditioning also depends on the size
of the stimuli.
Larger rewards produce a stronger response
than smaller ones.
More intense stimuli are better signals and
evoke greater conditioned responses.
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More fear, more saliva.
Preparedness Affects Learning
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Both instrumental and classical conditioning
are affected by preparedness (the innate
nature of the organism).
Flavor aversion learning is easier with taste
cues than with visual cues, but not shock.
Rooting behaviors interfere with learning for
pigs trained to put a wooden coin in a “bank”.
Some hamster behaviors are easier to learn.
Humans Show Preparedness
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Humans show preparedness too, appropriate
to our species.
Nausea can be associated with tequila but not
with friends or a shot glass.
Snake and spider phobias may be especially
prevalent due to preparedness.
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People associate shock with spiders or snakes
more readily than with flowers or mushrooms.