c82mpr – practical methods 2 dr mark haselgrove blocking and associative learning please log in...
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C82MPR – Practical Methods 2
Dr Mark Haselgrove
Blocking and Associative learning
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Structure of the Practical
Week 1: Introduction to the topic, background information
Homework: Reading
Week 2: Further background. Set up Experiment
Homework: Test Participants
Week 3: Introduction to Excel and SPSS, data exploration
Homework: Test more participants and explore data
Week 4: Data analysis, Introduction to PowerPoint, begin preparing presentations
Homework: Prepare presentation
Week 5: Present your finding, Q & A
Homework: Write-up practical report. Hand in by 4pm, 4th March
A reminder of some terminology and facts…
Unconditioned Stimulus (US): Biologically significant event (e.g. food, pain)
Conditioning and Learning
Unconditioned Response (UR): The response evoked by the US
Conditioned stimulus (CS): Previously neutral stimulus (e.g. tone) that acquires a response by being paired with a US
Conditioned response (CR): The response evoked by the CS
Shock
(US) → (UR)
Clicker → → Jumping Jumping
(CS) → (CR)
Hebb (1949)
Pairing a CS with a US is sufficient for learning to take place
Conditioning and Learning
“Whatever fires together, wires together”
CS
US
CS
US
CS
US
CS
-US
EventSensoryregister
Learningmechanism
Responsegenerator
Observedbehaviour
Kamin (1968)
Shock conditioning experiment with rats
Conditioning and Learning
Group Stage 1 Stage 2 Test
Blocking Noise → Shock Noise & Light → Shock Light
Control - Noise & Light → Shock Light
Lots of fearof the Light
No fearof the Light
Only learn about a CS if it followed byA SURPRISING US
Conditioning and Learning
Other examples of blocking….
Waelti, Dickinson & Schultz (2001): Blocking in Macaques
Stage 1 Stage 2 Test
Picture A → Juice
Picture B → no Juice
Pictures A & X → Juice
Pictures B & Y → Juice
X vs Y
Monkeys expressed more interest in Y than X
Conditioning and Learning
Other examples of blocking….
LePelley, Oakshott & McLaren (2005) Blocking in Cambridge undergraduates
Stage 1 Stage 2 Test
Food A → Illness
Food A & X → Illness
Food C & Y → Illness
X vs Y
Participants rated X as safer than Y
Rescorla & Wagner (1972)
- A mathematical theory of learning and surprise
Conditioning and Learning
Learning = intensity of CS x intensity of US x surprisingness of US
ΔV = α x β x (λ - ΣV)
Surprise = The difference between what you get and what you expect to get
CS US
Group Stage 1 Stage 2 Test
Blocking A → US AX → US X
Control - AX → US X
Conditioning and Learning
ΔV = α x β x (λ - ΣV)
Rescorla & Wagner model applied to blocking:
A
US
X
Conditioning and Learning
Your turn…
ΔV = α x β x (λ - ΣV)
Stage 1 Stage 2 Test
A → US AX → US X
Conditioning and Learning
Surprise brought about by a QUALITATIVE change in the US
Bakal, Johnson & Rescorla (1974) – Conditioned fear in rats
Group Stage 1 Stage 2 Test
Blocking A → shock AX → Loud Noise X
Control - AX → Loud Noise X
More fear X in Control groupthan Blocking group:
When blocking persists, despite a qualitatitive change in the nature of the US, we call the effect:
TRANS-REINFORCER BLOCKING
Conditioning and Learning
Surprise brought about by a QUALITATIVE change in the US
Stickney & Donahoe (1983) – Eye blink conditioning in rabbits
Group Stage 1 Stage 2 Test
Blocking A → left shock AX → right shock X
Control - AX → right shock X
Conditioned eye blink to Xin both groups:UN-BLOCKING
When blocking disappears, with a qualitatitive change in the nature of the US, we call the effect:
TRANS-REINFORCER UN-BLOCKING
Bakal et al (1974) – Conditioned fear in rats (TRB)Stickney & Donahoe (1983) – Eye blink conditioning in rabbits (TRuB)
Conditioning and Learning
Betts, Brandon & Wagner (1996) – Blocking in rabbits
No blocking when eye blink conditioning was measured
But, blocking was observed when “startle” was measured
HOMEWORK:
Read: Betts, Brandon & Wagner (1996)
Paper to be found on Mark Haselgrove’s website
How do we explain this discrepancy in the literature?
Could be an effect of: (1) different species, (2) different experimental procedure, (3) different apparatus, (4) different measure of behaviour.
References
Bakal, C. W., Johnson, R. D., & Rescorla, R. A. (1974). The effect of change in US quality on the blocking effect. Pavlovian Journal, 9, 97-103.
Betts, S. L., Brandon, S. E., & Wagner, A. R. (1996). Dissociation of the blocking of conditioned eyeblink and conditioned fear following a shift in US locus. Animal Learning & Behavior, 24(4), 459-470.
Hebb, D. O. (1949). The organisation of behaviour. New York: Wiley.
Kamin, L. J. (1968). Attention-like processes in classical conditioning. In M. R. Jones (Ed.), Miami symposium on the prediction of behvior: Aversive stimulation (pp. 9-32). Coral Gables, Fl: University of Miami Press.
Le Pelley, M. E., Oakeshott, S. M., & McLaren, I. P. L. (2005). Blocking and unblocking in human causal learning. Journal of Experimental Psychology-Animal Behavior Processes, 31(1), 56-70.
Rescorla, R. A., & Wagner, A. R. (1972). A theory of Pavlovian learning: Variations in the effectiveness of reinforcement and nonreinforcement. In A. H. Black & W. F. Prokasy (Eds.), Classical Conditioning II (pp. 64-99). New York: Appleton-Century-Crofts.
Stickney, K. J., & Donahoe, J. W. (1983). Attenuation of Blocking by a Change in Us Locus. Animal Learning & Behavior, 11(1), 60-66.
Waelti, P., Dickinson, A., & Schultz, W. (2001). Dopamine responses comply with basic assumptions of formal learning theory. Nature, 412, 43-48.