PSY402 Theories of Learning

1. PSY402Theories of Learning Monday January 13, 2003

2. Experimental Evidence • Rats drink little saccharin water at first but increase over time. • Loud tones (110 db) produce different responses depending on the background noise (60 vs 80 db). • Habituation occurred at 60 db • Sensitization occurred at 80 db • A loud background is arousing, leading to greater reactivity, not less.

3. Conditions Producing Change • More intense (stronger) stimuli produce stronger sensitization, less likely to produce habituation. • Greater sensitization and habituation occur when the stimulus is repeated frequently. • Changes in the stimulus prevent habituation. • Turkeys respond to shape changes.

4. Conditions (Cont.) • Sensitization can occur to many kinds of stimuli but habituation occurs only with innate responses. • Habituation and sensitization are transient (go away after seconds or minutes between stimuli). • Except long-term habituation. • Dishabituation – response returns when a sensitizing stimulus occurs.

5. Opponent-Process Theory • An explanation for addictions. • All experiences produce an affective reaction (pleasant or unpleasant) – A state. • This reaction gives rise to its opposite – B state. • B state is less intense and lasts longer. • Over time, the A state diminishes and the B state increases.

6. The Addiction Process • Tolerance – diminished A state. • Withdrawal – increased B state. • Addictive behavior is a coping response to the change in B state. • People try to enhance A state to offset the unpleasantness of the B state. • Without withdrawal symptoms there is no addictive behavior. • Time prevents B state strengthening.

7. What Sustains Addiction? • The B state is a non-specific aversive feeling. • Anything similarly aversive will motivate the addictive behavior, even if it has no relation to the substance. • Daily life stress produces a B state that results in behavior to create an A state. • Parachute jumpers – create a B state in order to feel the A state.

8. Acquisition of a Conditioned Response Chapter 3, pages 37-46

9. Acquisition, Extinction, and Spontaneous Recovery

10. Conditioned Emotional Responses • Fear is an anticipatory pain response based on past experience. • Fear is conditioned whenever a CS is associated with an aversive (painful or negative) event. • Fear motivates two responses: • Escape (when pain is present) • Avoidance (when pain is imminent)

11. Examples of Conditioning • Popcorn at the movies. • Fear of flying -- stronger with more turbulence (a stronger UCS). • An antelope shying away from low tree branches. • Nausea at the smell of alcohol after a hangover.

12. Conditioning Situations • Sign-tracking (autoshaping) – animals must recognize signs of food (UCS) and respond (UCR). • Pigeons pecking at key. • UCR, not an operant response, because behavior is specific to the stimulus. • Eyeblink conditioning • UCR is rapid, CR is slow. • Many trials are needed (100 pairings)

13. Fear conditioning • Avoidance is not a good measure of fear. • Suppression of an operant behavior occurs with a feared stimulus. • First – an operant behavior is learned. • Second – a CS is paired with an aversive UCS. • Third – the CS is presented in the operant chamber.

14. Suppression Ratio During CS SuppressionRatio = During CS + Without CS • The amount of time during and without the CS is equal. • The more fear, the lower the suppression ratio. • Ratios typically fall between 0 and .5

15. Flavor Aversion Learning • Garcia – rats will not drink water with saccharin if they get ill after drinking. • Significant avoidance occurs after just one trial. • Human food aversions are related to illness (89%). • Even if illness occurs hours later it is linked to the previous meal. • Not cognitive – know food not to blame