C 82 MPR Practical Methods 2 Dr Mark
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C 82 MPR – Practical Methods 2 Dr Mark Haselgrove Blocking and Associative learning Please log in with Windows 7
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 Power. Point, begin preparing presentations Homework: Prepare presentation Week 5: Present your finding, Q & A Homework: Write-up practical report. Hand in by 4 pm, 7 th April
Conditioning and Learning A reminder of some terminology and facts… Unconditioned Stimulus (US): Biologically significant event (e. g. food, pain) 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 Clicker → (CS) → Shock Jumping → Jumping (US) (CR) → (UR)
Conditioning and Learning Hebb (1949) Pairing a CS with a US is sufficient for learning to take place Event Sensory register CS US US Response generator CS CS-US CS Learning mechanism US “Whatever fires together, wires together” Observed behaviour
Conditioning and Learning Kamin (1968) Shock conditioning experiment with rats No fear of the Light Group Stage 1 Stage 2 Test Blocking Noise → Shock Noise & Light → Shock Light Control - Only learn about a CS if it followed by A SURPRISING US Lots of fear of the Light
Conditioning and Learning Other examples of blocking…. Waelti, Dickinson & Schultz (2001): Blocking in Macaques Monkeys expressed more interest in Y than X Stage 1 Picture A → Juice Stage 2 Test Pictures A & X → Juice X vs Y Picture B → no Juice Pictures B & Y → Juice
Conditioning and Learning Other examples of blocking…. Le. Pelley, Oakshott & Mc. Laren (2005) Blocking in Cambridge undergraduates Stage 1 Stage 2 Test Food A & X → Illness Food A → Illness X vs Y Food C & Y → Illness Participants rated X as safer than Y
Conditioning and Learning Rescorla & Wagner (1972) - A mathematical theory of learning and surprise CS US Learning = intensity of CS x intensity of US x surprisingness of US ΔV = α x β Surprise = The difference between what you get and what you expect to get x (λ - ΣV)
Conditioning and Learning Rescorla & Wagner model applied to blocking: ΔV = α x β x (λ - ΣV) Group Stage 1 Stage 2 Test Blocking A → US AX → US X Control - AX → US X 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 When blocking persists, despite a qualitatitive change in the nature of the US, we call the effect: TRANS-REINFORCER BLOCKING More fear X in Control group than Blocking group:
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 When blocking disappears, with a qualitatitive change in the nature of the US, we call the effect: TRANS-REINFORCER UN-BLOCKING Conditioned eye blink to X in both groups: UN-BLOCKING
Conditioning and Learning How do we explain this discrepancy in the literature? Bakal et al (1974) – Conditioned fear in rats (TRB) Stickney & Donahoe (1983) – Eye blink conditioning in rabbits (TRu. B) Could be an effect of: (1) different species, (2) different experimental procedure, (3) different apparatus, (4) different measure of behaviour. 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
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. , & Mc. Laren, 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.