Download Ch 12: Biological dispositions in learning

1/15/2015
Ch 12: Biological dispositions in
learning
Preparedness
• Innate tendency for an organism to more
easily learn certain types of behaviors or to
associate certain kinds of events together
• Occurs in both classical and operant
conditioning
• Fear conditioning, taste aversion conditioning
are best examples
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Conditioned Taste Aversions
• Classical conditioning where food that gets paired
with gastrointestinal illness becomes a
conditioned aversive stimulus
• If you get sick after eating something, you
associate that food with illness and never want to
eat it again
• The food is not usually the cause of the illness, as
in food poisoning, but alcohol,
radiation/chemotherapy, and flu can all be
sources of the illness.
Taste Aversion map
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•
•
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NS: USUR
Sweet water: x-ray irradiation  nausea
Sweet water (CS)  nausea (CR)
Stimulus generalization: other similar stimuli become
aversive as well as the original one
• Extinction can occur if repeated exposure to aversive food
item is not followed by illness
• Overshadowing: we develop the aversion to the more
intense/stronger flavor, rather than milder flavors that were
ingested at the same time.
• Latent inhibition: The more preexposure we have to
certain foods/flavors, the less likely we are to develop the
aversion to those. Rather, we “blame” illness on those
novel foods that we had little exposure to in the past.
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Taste Aversion is unusual case of
classical conditioning
• All 3 have adaptive benefits
• 1. Long delays. Classical conditioning hangs its hat
on trace delay, at longest. But how long do you
get sick after eating something?
• 2. One-trial conditioning. Single pairing of food
with illness is enough. If you try something more
than once, you might die.
• 3. Specificity of associations. We tend to
associate illness with food, rather than other
environmental stimuli such as people, TV shows,
or sounds. This is called CS-US relevance.
CS-US relevance
• Is a biological predisposition to associate some
events more closely with others.
• 1. flash of light, loud sound, and sweet water
paired together, then paired with either:
• 2. half of Ss got footshock, other half got
irradiation
• 3. Choice between “light and noise” or “sweet”
• 4. Ss exposed to footshock associated fear with
the sounds/lights; Ss exposed to irradiation
associated avoidance of the sweet water
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Interspecies differences in CS-US
• Birds associate visual cues with illness, while
rats associate taste/smell cues with illness
• Because of species differences in how they get
their food – birds rely a lot on vision, rats are
nocturnal and use smell to get their food
Sex differences
• Men and women have different sensory/
perceptual thresholds
• Females tend to be more discriminating about
odors, so they are more reactive to smells
associated with nausea and develop taste
aversions easier
• This includes pregnancy and morning sickness
events.
• The idea is adaptive; “better safe than sorry”
when it comes to the possibility of consuming
toxins
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Preparedness in operant conditioning
• Birds are more responsive to “songs” as
reinforcer for perching, and for “food” as
reinforcer for key pecking.
• Rats press a lever for food easier than lever
pressing to avoid shock; they learn to freeze or
run to avoid shock and not for food
• In fear conditioning, avoidance and escape,
Species-Specific Defense Reactions (SSDR) dictate
what an animal will do when it encounters
danger in its natural environment (e.g. freezing)
Instinctive Drift
• When trying to train animals for the circus and
other skills, sometimes their “natural” behaviors
take over and they do bizarre things that are not
predicted based on the training (esp. when
rewarded with food for those behaviors)
• Pigs were supposed to pick up a wooden coin and
insert into a piggy bank; eventually tossed in the
air and rooted : treating it like food
• Raccoons trained to do the same task eventually
began rubbing the coin between their paws
(miserly raccoon)
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Sign Tracking
• After classical conditioning, the Conditioned
stimuli begin to take on some of the appetitive
properties of the US.
• Organisms approach a stimulus that signals
the presentation of an appetitive event and
start treating that stimulus as though it were
the appetitive US (like the dog licking the light
or a bird pecking the key instead of the food
dish)
Adjunctive Behavior
• During an intermittent reinforcer schedule, there are times when
you CANNOT get reinforced (like immediately after rf)
• During the post-reinforcement pause, the development of other
behaviors (called “adjunctive”) occurs and those behaviors stay
strong.
– This includes water consumption, food consumption, and other bizarre
behaviors that have nothing to do with the reinforcer being used
– Development of adjunctive behaviors is increased when the
deprivation of reinforcer is strong
– Adjunctive behaviors are reinforcing and can be used as reinforcers
during post-reinforcement times
– Moderate (not too short or long) time between reinforcers is the best
time frame to develop adjunctive behaviors
• What kind of behaviors do we engage in when we have to wait for
prolonged periods of time?
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