The Modification of Instinctive
Behavior
Chapter 3
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



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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).
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.


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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.
Lorenz Energy Model
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

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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.)


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.
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.
Evolutionary Theory

Eisenstein et al. suggest that this is
a fine-tuning of sensory stimuli to
recognize important stimuli.



Habituation & sensitization are nonassociative 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



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



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.


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.



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.