View
233
Download
3
Category
Tags:
Preview:
Citation preview
Chapter 8 – Stimulus Control of Behavior
• Outline 1– Identification and Measurement of Stimulus
Control• Differential Responding and Stimulus Control• Stimulus Generalization• Stimulus Generalization Gradients as Measures of
Stimulus Control
– Stimulus and Response Factors in Stimulus Control• Sensory Capacity and Orientation• Relative Ease of Conditioning Various Stimuli• Type of Reinforcement• Types of Instrumental Response
• The concept of behavioral control– S (stimulus)
• Can elicit responding (R)• Can create expectancies (O)
• “Appropriate behavior” is often controlled by cues (stimuli) in our environment.– Get undressed for bed – Get undressed at school
– Kiss girlfriend/boyfriend– Kiss random person walking on campus
• This chapter considers how stimuli come to control our behavior.
• Identification and Measurement of Stimulus Control– How do we know that a behavior is under
stimulus control?• Consider Reynolds (1961)
– Train pigeons to peck a white triangle on a red background.• VI schedule
– Elicited steady pecking
– Test with red key (no triangle)– Or white triangle (no red; background is black)
• Stimulus Generalization– How specific is stimulus control?
• Early researchers (like Pavlov) examined this question.
• Guttman and Kalish (1956)– Train
• VI schedule• S+ = 580nm light (yellowish orange).
– Test• Different colors
– 520 nm (green) – 540 nm– 550 nm– 570 nm (yellow)– 580 nm (yellowish orange)– 590 nm (orange)– 600 nm– 620 nm– 640 nm (red
• Random order• In extinction
Generalization Gradient
• The generalization gradient indicates stimulus control by color.– It is somewhat specific for the training
stimulus.• But generalizes to similar colors.
• There is no gradient for the hypothetically color blind pigeons– Color does not control responding.
• What determines the degree of stimulus control obtained?
• Stimulus and Response Factors– Sensory Capacity and orientation
• Must be able to sense it – Rats don’t do well with color stimuli– They do very well with odor stimuli.
• Horse study from book.– Trained to select color over gray.
» Push lever with head.» 85% correct
» All 4 picked blue and yellow over gray» 3 picked green over gray» Only 1 picked red over grey
» Implies they may have poor red sensation
• Relative ease of conditioning various stimuli.– Whether a stimulus exerts control depends on
whether it stands out from other cues in the environment
– Children’s book• Big pictures• Smaller words
– Overshadowing (first noticed by Pavlov)• CS1 – loud sound• CS2 – dim light• More conditioning occurred to the stronger stimulus
– Conditioning was better for CS2 if presented alone– Overshadowed by CS1 if presented together
• Type of Reinforcement– Aversive vs. Appetitive seems to matter
• Foree and LoLordo (1973)– Two groups of pigeons– Both were trained to respond when presented with a
compound discriminative stimulus• Red light and tone
– Group 1• Step on treadle to gain food
– Group 2• Step on treadle to avoid shock
– Test both groups with• Red light alone• Tone alone
• Visual stimuli tend to gain control over appetitive stimuli
• Auditory stimuli tend to gain control over aversive stimuli.
• Behavior systems?– Food RF activates feeding system?
• Rats and pigeons are more likely to find food with vision rather than hearing.
– Shock RF activates defensive system?• Auditory cues may be particularly adaptive for
avoiding danger.
• Outline 2– Learning Factors in Stimulus Control
• Stimulus Discrimination Training• Effects of Discrimination Training on Stimulus Control• What is Leaned in Discrimination Training?• Interactions Between S+ and S-: Peak Shift Effect• Range of Possible Discriminative Stimuli• Stimulus Equivalence Training
– Contextual Cues and Conditional Relations• Conditioned Place Preference
• Learning Factors in Stimulus Control
– left to their own devices animals come under stimulus control based on the stimulus and response factors discussed above.
– But can we train animals to make finer distinctions?
• Stimulus Discrimination Training.– Let’s go back to the color generalization study– Train
• VI schedule• S+ = 580nm light (yellowish orange).
– Test• Different colors
– 520 nm (green) – 540 nm– 550 nm– 570 nm (yellow)– 580 nm (yellowish orange)– 590 nm (orange)– 600 nm– 620 nm– 640 nm (red
• Random order• In extinction
Generalization Gradient
• Note that the pigeons treated the 590 nm stimulus nearly the same as the 580 nm
• Can they tell the difference?
• How could we find out?
• Train with two stimuli.– In operant conditioning we call them S+ (Sd) and S- (S∆)
• S+ responding will result in RF• S- responding will have no effect
– Pavlovian• CS+ (CS-US)• CS- (CS- no US)
• For our color discrimination – S+ = 580 nm– S- = 590 nm
Hypothetical Result
• Effects of Discrimination on Stimulus control– Increased stimulus control
• 1) Discrimination narrows the generalization curve• 2) Discrimination within a dimension narrows it even more
– Makes the relevant dimension clear?» Tone vs. loudness
• Example: Jenkins and Harrison (1962)– Trained with tones
• 3 groups– 1) generalization
» S+ 1000-cps tone– 2) discrimination
» S+ 1000-cps tone» S- no tone
– 2) within discrimination» S+ 1000-cps tone» S- 950 cps tone
• What is learned in Discrimination Training?– Example
• S+ (light) S- (tone)
• 1) learn about S+ alone– Respond during light
– Learn nothing about tone
• 2) learn about S- alone– Suppress responding during tone
• Learn nothing about light
• 3) learn about both (Spence’s Theory)– Respond during light– Suppress responding during tone
• Spence’s Theory of Discrimination Learning– The S+ becomes excitatory
• Signals RF
– The S- becomes inhibitory• Signals lack of RF
• How do we test this?– Responding to S+ and not responding during
S- is not enough• Any of the 3 theories predict this
• The peak shift can be considered evidence for Spence’s view.
• Range of Possible Discriminative Stimuli– Many kinds of stimuli have been examined
• Simple– Color– Tone
• Complex– Number– Time of day– Kind of music
» Carp » Blues vs. Classical» John Lee Hooker vs. Bach
• Types of Stimuli continued– Artists
• Monet vs. Picasso
– Internal• Hunger• Drugs
• Drugs– Cocaine = left lever– Saline = right lever
• Antagonist?• Other drugs?
– Amphetamine?– Caffeine?
• Stimulus Equivalence Training– We have seen that discrimination can sharpen
stimulus control• Treat similar stimuli differently
– Can we produce the opposite effect. • Train animals to treat very different stimuli
similarly?
• Honey and Hall (1989) Group 1 Group 2
• Phase 1 Noise = Food Noise = nothing
Clicker = Food Clicker = Food
• Phase 2 Noise= foot shock Noise = Foot
shock
• Test Clicker Clicker
• Which group is more afraid of the clicker?– Group 1
• Seems a common outcome causes the rats to treat the stimuli similarly.
• Common Coding – a typical equivalence experiment– Based on Urcuioli, Zentall, Jackson-Smith, and Steirn (1989)
• Phase 1 (Many-to-One Matching-to- Sample)• R R+G-• V R+G-• G G+R-• H G+R-
• Phase 2 (new comparisons)• R B+Y-• G Y+ B-
• Test (does learning transfer)?• V B Y?• H Y B?
• Does Equivalence training cause stimuli to become harder to discriminate?– Based on Kaiser, Sherburne, Steirn, and Zentall (1997)
• Train• R R+G-• V R+G-• G G+R-• H G+R-
Test (discrimination)• Consistent Inconsistent• R+ R+• V+ V-• G- G-• H- H+
• Which Group learns faster?
– pecks S+ 90% of the time
• Sidman – True equivalence must demonstrate three
concepts • 1) Reflexivity (sameness)
– If A = A, B = B, C = C, and so on. • 2) Symmetry (bidirectional equivalence)
– If A = B then B = A• 3) Transitivity (transfer equivalence across
stimuli)– If A = B and B = C then A = C
• Spoken and written speech involves these three aspects of equivalence.
• Reflexivity (sameness)– Apple = Apple– Orange = Orange
=
=
• Symmetry (bidirectional equivalence)– A(object) = B (word) – B (word) = A (object)
• = Apple
• Apple =
• Transitivity. – If A (object) = B (spoken word)– And B (spoken word) = C (written word)– Then A (object) = C (written word)
• If =
• And = Apple
• Then = Apple
• Some have argued stimulus equivalence is a human trait– Requires language
• People with good verbal skills can form equivalent relationships easily.
• Those without have much more difficulty.
• Animals?
• Reflexivity (sameness)– Pick the thing that looks the same
• Based on Zentall and Hogan (1978)
• Train (Identity matching-to-sample)– R R+G-– G G+R-
• Test (with “novel” stimuli)– B B Y– Y Y B
• Symmetry (bidirectional equivalence)– Based on Zentall, Sherburne, and Steirn (1992)
• If red = food, then food = red• If green = no food, then no food = green
• Train (differential outcomes procedure)– R R+G- (food)– G G+R- (noFood) do over until correct to move on
• Test– Food R G? – No Food G R?
• Transitivity– Based on Steirn, Jackson-Smith and Zentall (1991)
• Phase 1 (Differential Outcomes)
– R R+ G- (food)– G G+ R- (no food)
• Phase 2 – food B+ W-– no food W+ B-
• Test– R B W?– G B W?
• Train (Differential Outcomes)• Phase 1
– R R+ G- (food)– G G+ R- (no food)
• Phase 2 – food B+ W-– no food W+ B-
• Test– R B W?– G B W?
• Contextual Cues and Conditional Relations– Conditioned Place Preference
• Inject Rat with drug and confine to one side of chamber
• Test later (next day) – Drug free– Which side do they prefer?
• Heroin – Good sick?
• Two groups of Thirsty Rats– Morphine Group
• Inject with morphine• Place in Side 1 with Sacch.
– Control• Inject with Saline• Place in Side1 with Sacch.
• Test– open access– two bottles in each side
• Sacch vs. Water
• Results– Morphine Group?
• More time in Side 1• avoid Sacch.
– Control?• Equal time each side• prefer Sacch.
Recommended