• Adaptive change in behavior that results from past experiences Learning • Nonassociative Learning – – • • Instrumental Learning/

Habituation Sensitization

• Ability to discontinue • Increase in response to highly responsiveness as repetitive stimuli result of • Sokolov (1963) – repeated application of – Delayed Train – aversive stimulus

Habituation can be short-term or long-term, depending on Habituation and Sensitization presentation and interval between stimuli.

Characteristics of Habituation and Sensitization Short-term habituation: -rapid presentations of a stimulus with a short interval Time course between presentations -results in habituation quickly but see spontaneous Sensitization is usually temporary recovery -sensitization can last for up to a week but not -the degree of depends on length generally a long-term effect. of rest interval. -with a stronger stimulus, the effects last longer.

1 1. Short-term habituation 2. Spontaneous recovery 3. Long-term habituation Long-term habituation: -one stimulus presentation a day -see more long-term effects -see less spontaneous recovery

4. Rate of habituation faster for short ISI 7. Habituation is specific – generalization gradient 5. Rate of habituation faster for weaker stimuli 8. 6. Below-zero habituation 9. Habituation of dishabituation

Habituation/Dishabituation Stimulus specificity Habituation is stimulus-specific • GSR measured at -if you change the stimulus, see recovery of the onset of either high or response low tone – Tone gradually elicits Sensitization is not highly stimulus-specific less anxiety -if an animal is aroused, it is usually aroused to a th •15 trial is the variety of cues opposite tone – high for low group & low for high group

2 Effects of strong extraneous stimuli Habituation and Sensitization in Aplysia If you change the nature of the eliciting stimulus you see recovery of the habituated response.

Can also see recovery of the response if the animal is given a rest period = spontaneous recovery.

The response can also be restored by presenting a strong stimulus— this is called sensitization

Dishabituation refers to recovery of the response to the habituated stimulus following presentation of a different, novel stimulus.

Habituation of the gill withdrawal results from changes in the S-R pathway Sensitization

Less transmitter After the gill withdrawal reflex has habituated, a shock to released here the tail sensitizes the gill withdrawal reflex elicited by touching either the mantle or siphon Skin SN MN

Gill

Sensitization occurs because tailshock augments the release of from the Habituation vs. Sensitization sensory neuron Habituation Sensitization Tail FN • Decrease in strength • Increase in strength of behavior of behavior • Typically low-intensity • Typically high- stimuli intensity stimuli Skin SN MN • Stimulus-specific • Nonspecific generalization generalization • < neurotransmitter • > neurotransmitter

Gill

3 Pavlov Classical Conditioning

• Process by which a neutral stimulus (CS) comes to be associated with another stimulus (UCS) that elicits a response (UCR) • Results in elicitation of response by CS

Pavlov paired the clicking of a metronome with food.

Clicker Food (never used a bell)

Dogs normally salivate with food but not with the clicker

After a few of these pairings, dogs began to salivate when the metronome came on.

Four major terms apply to Pavlovian Conditioning experiments Sequence in Conditioning Stimuli Responses • Initially the neutral UR US stimulus elicits no Unconditioned response Unconditioned stimulus The unlearned response response Biologically potent stimulus that triggered by the US reliably evokes an unlearned or • UCS elicits reflexive Powerful and reflexive response (UCR) reflexive reaction (i.e., food) (i.e., salivation to food) • Pair NS w/ UCS & elicit UCR CS CR Conditioned stimulus Conditioned response • CS elicits salivation Biologically weak stimulus It is elicited by the CS and – UCR=CR salivation The CS may evoke an orienting represents the learned behavior response, but not the strong response evoked by the US (i.e., salivation to the Metronome) (i.e., metronome)

4 Appetitive & Aversive Timing Conditioning Appetitive Aversive • US is an event the • US is an event the organism seeks out & organism avoids & considers pleasant considers unpleasant –food – shock –physical touch – painful stimulus –warmth – air puff in eye

Phases of Learning

• Acquisition – phase • Diminishment of response when w/strengthening of is discontinued response through repeated

Acquisition & Extinction Acquisition and Extinction

• Spontaneous Recovery

5 What is learned? Pavlov

• Stimulus-Stimulus Associations • Stimulus-substitution theory CS – CS becomes directly associated with the UCS – A connection forms in the brain between the CS and the UCS and so elicits a similar/related response to the UCS activation sites – When the CS is activated UCR UCR alone following acquisition, it will automatically activate the • Stimulus-Response Associations UCS site in the brain – Therefore, the CR should be CS – CS becomes directly associated with the UCR almost identical to the UCR and so elicits the same response as the UCR (because the connection UCS between UCS and UCR in the brain is hardwired) UCR/CR

Support: Stimulus Substitution Against Stimulus Substitution

• Water Group • CR not always the same as UCR – CS(light)ÆUCS(water) Water Grain – Pigeons tried to “drink” the – When tone paired with shock, rats will jump to lit key the UCS (shock), but the CR is typically • closed beak and open eyes freezing • Grain Group – CS(light)ÆUCS(grain) CS – Pigeons tried to “eat” the lit key UCS • Open beak and closed eyes

Jenkins & Moore (1973) CR UCR

Other stimulus-response models Siegel (1972)

• Preparatory Response Model –Kimble • Gave rats repeated – CR is a response that serves to prepare the organism for the injections (CS) of insulin upcoming UCS (UCS) – Insulin’s effects are to – CR eyeblink may actually prepare the person for the upcoming reduce the level of airpuff such that the eye would be partially closed when the glucose in the blood airpuff occurs (UCR) • Compensatory Response Model • Give rats injection of saline – Siegel – Measured the CR (change in blood glucose – Learned between CS and UCS serves to elicit a CR levels) that compensates for effects of UCS • Glucose levels increased – Sometimes CR=UCR • CR ≠ UCR, and the CR was – Sometimes CR opposite of UCR definitely compensatory • Evidence for compensatory response model

6 Conditioned

• Siegel, et al., 1978 45 – Experimental Group: CS (light change & noise w 40 reduction) paired with UCS 35 (injection of morphine) for 9 30 days 25 – Control Group (CS 20 paired with injection of saline) 15 – Unpaired Control Group 10

•Test: present CS, inject Pa Lick to Latency Mean 5 every rat with morphine, 0 place rat on hot surface Placebo Experimental Control – Measure latency to lick their paws (lick when they feel pain)

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