The Modification of Instinctive Behavior

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. • https://www.youtube.com/watch?v=7PcteKRA3zs • 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. Lorenz Energy Model

5. 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).

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

7. Stickleback Fish Mating Instinct

8. Tinbergen’s Levels (see Fig 3.2)

9. Conflicting Motives • If two incompatible signs appear at the same time, energy flows to a third instinct system. • The occurrence of this third behavior is called displacement. • https://www.youtube.com/watch?v=hcS_h75Aa9g

10. Conditioning Affects Behavior • Conditioning experiences can change sensitivity to releasing signs. • Only the consummatory response (eating, mating) at the end of a chain of behaviors cannot be changed. • Conditioning fine tunes the response to the environment and enhances survival – as in jackdaw nest building.

11. 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.

12. Aplysia (Sea Slug) Habituation

13. Aplysia Neural Network

14. 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

15. Ingestional Neophobia Habituates

16. 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.

17. 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.

18. 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.

19. Conditions (Cont.) • Habituation may lead to decreased reward effectiveness; sensitization increases reward effectiveness. • Intensity of responding does not decrease when a variety of rewards are used. • Decreased habituation results in renewed eating – dessert tray at restaurant. • Overweight people consume a greater variety of foods.

20. 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.

21. Dual-Process Theory

22. 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.

23. Dishabituation • Habituation disappears when the environmental stimulus changes. • Caused by disruption of habituation not sensitization. • 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.

24. 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.

25. Aplysia (Sea Slug) Habituation

26. 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.

27. Opponent Process Model

28. 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.

29. Cognitive Explanations • In order for addiction to occur, Solomon suggests that people must recognize that abstinence causes withdrawal. • When people attribute other causes to the symptoms, no addiction occurs. • Some people do not become addicted because of the time spans between exposures to the drug/alcohol.

30. 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.