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The Modification of Instinctive Behavior Chapter 3.

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Presentation on theme: "The Modification of Instinctive Behavior Chapter 3."— Presentation transcript:

1 The Modification of Instinctive Behavior Chapter 3

2 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.

3 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).

4 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).

5 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.

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

7 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.

8 Lorenz Energy Model

9 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.

10 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

11 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.

12 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 habituate but respond again if the shape changes.

13 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.

14 Dual Process Theory  Groves & Thompson suggest that sensitization originates in the central nervous system. Drugs that stimulate the CNS increase readiness to respond.  Garcia suggests that the ability to modify innate reactions has considerable adaptiveness.

15 Evolutionary Theory  Eisenstein et al. suggest that this is a fine-tuning of sensory stimuli to recognize important stimuli. Habituation & sensitization are non- associative forms of learning. Their function is to modify sensory thresholds to adjust to environment.  High responders & low responders adjust in different ways to same stimulus.

16 Cellular Modification Theory  Aplysia – California sea slug  Learning can permanently alter the functioning of neural systems.  The change takes place at the synapse of the neurons. Stimulation by an external stimulus produces the change.

17 Dishabituation  Habituation disappears when the environmental stimulus changes.  In the aplysia, the neural status may return to the previous condition.  An alternative view is that sensitization occurs to modify the responding. The mechanism remains unclear.

18 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.

19 Opponent Process Model

20 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.

21 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.

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