PSY402 Theories of Learning Chapters 2 & 3

Acquisition, Extinction, and Spontaneous Recovery

Little Albert

Watson & Raynor  Human fears can be acquired through Pavlovian conditioning. Rat paired with loud noise Stimulus generalized to other white objects (white rabbit, white fur coat)  Mary Cover Jones developed counterconditioning -- a technique for eliminating conditioned fears. Acquisition of fear-inhibiting response

Ethics of Learning Research  Animals and humans are now protected by oversight and ethical guidelines.  Pain or injury to animals must be weighed against and justified by the knowledge to be gained.  Electric shock typically is uncomfortable and upsetting but not physically harmful.

Instinctive Systems  Lorenz & Tinbergen – evolution occurs when a species incorporates environmental knowledge into its genetic structure. Greylag goose and egg-rolling.  Learning can sometimes modify instinctive behavior – even though the fixed action patterns are innate.

Energy Model  Action-specific energy builds up but is blocked (inhibited).  The energy motivates appetitive (approach) behavior.  Presence of a sign stimulus releases the energy by stimulating an innate releasing mechanism.  The behavior occurs as a fixed action pattern (or chain of actions).

Releasing Signs  Releasing signs can be complex: Grayling butterfly signs include darkness of female, distance from male, and pattern of movement.  Intensity of the sign influences the behavior but so does the amount of accumulated energy (time since the last response).

Hierarchical System  Specific behaviors are controlled by a central instinctive system.  Energy can accumulate at each level in the system. Hormones generate energy.  Release of energy at higher levels flows to lower levels.  The sign stimulus determines which behavior will occur.

Conflicting Motives  If two incompatible signs appear at the same time, energy flows to a third instinct system.  This third behavior is called displacement.

Conditioning Affects Behavior  Conditioning experiences can change sensitivity to releasing signs. Only the consummatory response (eating, mating) at the end of a chain cannot be changed.  Conditioning fine tunes the response to the environment and enhances survival.

Criticisms of the Energy Model  Best viewed as a metaphor.  The brain does not literally accumulate energy in any centers and nothing flows.  Willows & Hoyle – alternating contractions in sea slug allow it to escape from a starfish. Brain areas producing this response do not correspond to energy model.

Acquired Changes in Response  Habituation – response to a repeated stimulus decreases with experience.  Sensitization – response to a repeated stimulus increases with experience.  Examples: Ingestional neophobia, fear of new food Startle response

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.

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.

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.

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

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.

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.

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

Acquisition, Extinction, and Spontaneous Recovery

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)

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.

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)

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.

Suppression Ratio D uring CS SuppressionRatio = D uring 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

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