SUMMARY NOTES/OUTLINE Two-Process Theory Dual Process Theory (Groves and Thompson) Groves and Thompson Important features: Curious phenomena A. 2 Processes: 1. Habituation (H) 2000 1800 2. Sensitization (S) 1600

1400 B. Both activated when stimulus is presented 1200 1000 C. Behavior = H + S 800 600 If H > S; Decrease Response 400 200 If S > H; Increase Response 0 051015 20 D. Different Neurophysiological Processes Triiiallls H: specific change in S-R reflex arc S: general state of arousal 1. Humped habituation curves

Net (observed) behavior = 2. Sometimes habituation, sometimes sensitization Sum of the opposing H and S processes Initial Habituation S Response 2000 1800 Amplitude 1600

1400 1200 1000 800 Net Behavior 600 Sensitization 400 H 200 0 051015 20 Triiiallls

S process Greater activation State of arousal of the S process Sensory Nerve Initial response S>H baseline S>H + H process

H>S Motor H>S Nerve

1 S - 45V

More Sensitization Process S - 7V with Intense Stimulus, not Initial Necessarily less Habituation 100 Response

45 V

25 V 50 7 V H Response Amplitude

0 Weird! 0246810 Strong Less Learning??!! Blocks of Trials

Immediate Test: Groves and Thompson “Dishabituation” Dual Process Theory

Summary of interpretation of Characteristics of Habituation

At all times, behavior is the summation Delayed Test: of the S and H processes Habituation Returns ? Response Amplitude Faster Habituation with weaker stimuli is because there is less activation of the S process. Trials “Dishabituator” Dishabituation is NOT the loss of H, but rather the addition of S. The dishabituator activates S. Easier to explain as transient activation of a sensitization process

Q: You repeatedly present a tone to an animal and his startle Post- response gets smaller over trials. What do you conclude? synaptic

Cell Body Synapse Learning-Performance Distinction (again) (soma) Presynaptic Other possible reasons for decreased response?

Motor Fatigue Sensory Adaptation Action Potential Axon For it to be “learning” must be a change in the Dendrites Terminal processing of information in the CNS

How to Test? Evoke response with different stimulus (discrimination test) Dishabituation (pages 56-57)

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