Transcript Research Methods Lec 6

Animal Research
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Problem of Variability of human participants
Use Animals to increase control
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Rearing - littermates
Genetics – littermates, inbred strains
Experience- what they were exposed to
Environmental conditions – food, water, lighting,
temperature, cage size, etc.
Use of animals
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To reduce variability
To study basic processes
To study special variables that can’t be tested
in humans – e.g. brain function
To learn more about animals
Research Designs
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Random Groups
Split litter (Matched groups)
Within subjects
Mixed designs
Small N design (ABA design)
Classical Conditioning
Instrumental Conditioning
Ethological methods
Classical Conditioning
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Pavlov
Digestion
Salivation
Dogs
Inappropriate salivation
Psychic secretions
UCS, UCR, CS, CR, contiguity
Classical Conditioning of drug
related stimuli
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UCS = morphine
UCR = Heart rate decrease
CS = drug stimuli
CR = ??
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CR = heart rate up!
Compensatory response
Drug Overdose
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CS is different
UCS = same as before
CR = no compensatory response
Heart rate too low – person dies
Contiguity Theory
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Pavlov’s explanation
Two events that occur closely together will
become associated
Temporal contiguity
Spatial contiguity
Methods in Classical Conditioning
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Tests of Contiguity theory
CS – UCS temporal relationships
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Square wave diagram
Simultaneous conditioning
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Delayed conditioning
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Short – delay
Long - delay
Trace conditioning
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results
Short – delay
Long - delay
Backward conditioning
Inhibitory Classical Conditioning
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Excitatory classical Conditioning
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A CR is produced
Inhibitory classical conditioning
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A CR is inhibited
Must first have excitatory to demonstrate
inhibitory
Pop quiz example
Higher – Order conditioning
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Diagram
Sequence of CSs
Waterfall example
Sensory Preconditioning
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Pair two stimuli for several trials
Use one as a CS until you get CRs
Test other stimulus
Do you get a CR to second stimulus?
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Yes
Pairing stimuli before training in some way
makes them equivalent
Evidence for S – S association in classical
conditioning
CS – UCS association produces conditioning
Other methods: Preexposure
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CS pre-exposure
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Present CS alone for several trials (16-20trials)
Pair CS with UCS in excitatory conditoning
Test for CR
UCS pre-exposure
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Present UCS alone for several trials
Pair UCS with a CS
Test for CR
Measuring the CR
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Determining if CR occurs
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Omit the UCS
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Probe trials
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See if CR occurs
Problem: Extinction occurs
See if CR occurs on probe trial only (e.g. 1/15)
Measuring Strength of CR
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Frequency –e.g. 7/10 probe trials
Latency – e.g. number second to produce CR
Magnitude – e.g. number of drops of saliva
Discrimination
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A tool to measure other behaviors
Pavlov – discrimination of shape by dogs
CS+ paired with ucs = CR
CS- not paired with ucs = no CR
Experimental neurosis
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CS+ = circle
CS- = ellipse (9:1)
Dogs became neurotic
Generalization
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A tool to study other behaviors
Train on one CS (e.g. cs = red)
Test on new CS’s (orange, bluish red, etc)
The more similar the new CS’s the more
generalization that occurs
Generalizaton gradient
Training one stimulus trains a whole host of
stimuli
Extinction
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As a tool to measure the strength of CR
Present CS without UCS
CR dies out or extinguishes
Pavlov – extinction involves the active
withholding of the CR
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Spontaneous recovery
Faster relearning
Instrumental Conditioning
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Instrumental/Operant =The consequences of a
response change the future probability of the
response
Classical
vs
Instrumental
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Subject passive
Stimuli imposed
Behavior elicited
S – S; S – R
Autonomic mainly
subject active
stimuli unknown
Behavior emitted
R–S
skeletal mainly
Pre-training Procedures
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Deprivation
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85-90% body weight
Weigh dailey
Calculate food amounts
Handling
Sampling the reinforcer
Adaptation to apparatus
Magazine training
Pre-training (Cont.)
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Measure operant level
Shaping
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Autoshaping
Successive approximation
Now ready to start experiment
Instrumental Designs
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Free Operant (Skinner)
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Operant chamber
Animal free to make response at any time
DV = rate of responding (responses/unit time)
Cumulative responses
Cumulative recorder
Interpret graphs of data
Small-n design
Discrete Trial
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Response can only occur at a time specified by
the researcher (Thorndike and others)
Many possible DVs
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Latency – straight alley, Morris water maze
Speed of response – straight alley
Choice – T-maze
Percent correct – Stone maze, WGTA
Errors – complex maze
Reinforcement
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A reinforcer is any thing (stimulus) that
increases the probability of the response that it
follows.
Must make sure that a stimulus actually is a
reinforcer first before using it to change
behavior
E.g “gold stars”
Types of Reinforcement
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Positive Reinforcement
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A response, followed by the presentation of a
reinforcing stimulus, increases the future
probability of the response.
A hungry rat presses a lever to get food
Mom gives junior a cookie for picking up his toys
Negative Reinforcement
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Also called “escape training”
A response, followed by the withdrawal of the
reinforcing stimulus, increases the future
probability of the response
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A rat jumps a low hurdle and a loud noise is turned
off
A person, stopped at a red light, rolls up the car
window to decrease the sound of a jack hammer
working on the concrete curb
Punishment
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A punisher is any thing (stimulus) that
decreases the probability of the response that it
follows.
Must check to see that a stimulus is a punisher
E.g. tantrums
Types of Punishment
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Punishment by presentation
A response, followed by the presentation of a
punishing stimulus, becomes less probable in
the future
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A rat, steps off a pedestle and gets shocked
Johnny hits his sister and gets spanked by dad
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(What’s Johnny learning here?)
Punishment by withdrawal
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Also called “ omission training”
A response, followed by the withdrawal of a
positive reinforcer, decreases the future
probability of the response
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A rat, presses a lever, and as a result, loses access
to food for 60 seconds
Johnny hits his sister, and as a result, doesn’t get to
watch his favorite violent cartoon show
Categories of Reinforcement
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Primary
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Unlearned
Physiological
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Food
Water
Sex
Pain
Categories of Reinforcement
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Secondary/Conditioned
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Learned
Neutral initially
Paired with a primary reinforcer
Tokens/token economies
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Chimps
Strip mines
Categories of Reinforcement
Social
Attention
Affection
Praise
Trans-situational
Paired with several reinforcers
Money
Schedules of Reinforcement
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Simple Schedules (only one requirement for
reinforcement)
Ratio Schedules (responses)
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Fixed Ratio
Variable Ratio
Interval Schedules (time)
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Fixed Interval
Variable Interval
Ratio Schedules
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Fixed Ratio (e.g. FR10)
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Number of responses per reinforcement is fixed
and unchanging
No reinforcement for responses until the ratio is
completed: last response produces reinforcer
In well trained subjects:
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Ratio is run off all at once
Post-reinforcement pause
E.g. piece work
Variable Ratio
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Variable Ratio (VR10)
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Number of responses required is constantly
changing from one reinforcement to the next
Unpredictable
Best strategy:
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Work fast
Work consistently
E.g. gambling
Interval Schedules
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Fixed Interval (FI60)
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Best strategy:
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Amount of time that must pass between
reinforcements is fixed.
Predictable
Wait until appropriate amount of time has passed
Scallop shaped records
E.g. test dates
Variable Interval
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Variable Interval (VI60)
Amount of time that must pass between
reinforcements is constantly changing
Unpredictable
Best strategy:
Work consistently
E.g. pop quizzes
A tool for studying other behaviors
Complex Schedules
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More than one requirement must be met
Often used as tools to study other aspects of
research
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DRL
Progressive ratio
Discrimination
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Differential responding to stimuli
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Sd – sets occasion for reinforcement
S-delta – sets occasion for non-reinforcement
As in classical conditioning, discrimination can be
used as a tool to study other behaviors
E.g. recognition memory in monkeys using DNMS
Generalization
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Same as in classical conditioning
Can be used to study other behaviors
Reinforce behavior in presence of one
stimulus, look at how the behavior generalizes
to other similar stimuli
E.g. taking notes in biology class – taking
notes in psychology class.
Extinction
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Also like classical conditioning
Used to study other behaviors
E.g. preference for a reinforced location in the
Morris water maze.
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Study annulus crossings during extinction