The Modification of
Instinctive Behavior
Chapter 3
Instinctive Systems

Lorenz & Tinbergen – evolution occurs when
a species incorporates environmental
knowledge into its genetic structure.
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Greylag goose and egg-rolling.
Learning can sometimes modify instinctive
behavior – even though the fixed action
patterns are innate.
Energy Model
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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).
Lorenz Energy Model
Releasing Signs

Releasing signs can be complex:

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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

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Specific behaviors are controlled by a central
instinctive system.
Energy can accumulate at each level in the
system.

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Hormones generate energy.
Energy released at higher levels flows to
lower levels.
The sign stimulus determines which behavior
will occur.
Stickleback Fish Mating Instinct
Tinbergen’s Levels (see Fig 3.2)
Conflicting Motives

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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.
Conditioning Affects Behavior

Conditioning experiences can change
sensitivity to releasing signs.

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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 sea
slug.
Aplysia (Sea Slug) Habituation
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

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Habituation – response to a repeated stimulus
decreases with experience.
Sensitization – response to a repeated
stimulus increases with experience.
Examples:
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Ingestional neophobia, fear of new food
Startle response
Experimental Evidence

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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).

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Habituation occurred at 60 db
Sensitization occurred at 80 db
A loud background is arousing, leading to greater
reactivity, not less.
Conditions Producing Change

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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.
Conditions (Cont.)

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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).

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Except long-term habituation.
Dishabituation – response returns when a
sensitizing stimulus occurs.
Dual Process Theory

Groves & Thompson suggest that
sensitization originates in the central nervous
system.

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Drugs that stimulate the CNS increase readiness
to respond.
Garcia suggests that the ability to modify
innate reactions has considerable
adaptiveness.
Evolutionary Theory

Eisenstein et al. suggest that this is a finetuning of sensory stimuli to recognize
important stimuli.

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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.
Cellular Modification Theory
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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.
Dishabituation

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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.
Opponent-Process Theory
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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.
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B state is less intense and lasts longer.
Over time, the A state diminishes and the B
state increases.
Opponent Process Model
The Addiction Process
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Tolerance – diminished A state.
Withdrawal – increased B state.
Addictive behavior is a coping response to the
change in B state.
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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.

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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.