15.1.8

Innate Releasing Mechanisms & Fixed Action Pattern

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Innate Releasing Mechanisms (IRM) and Fixed Action Patterns (FAP)

Ethological explanations view aggressive acts as governed by innate releasing mechanisms (IRM) and fixed action patterns (FAP).

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Definitions

  • An innate releasing mechanism is a built-in physiological process or structure, for instance a network of neurons in the brain.
  • An environmental stimulus triggers the IRM which then releases a specific sequence of behaviours called a fixed action pattern, or FAP.
  • Lea (1984) has suggested six main features of FAP’s:
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Lea (1984) FAP features

  • Stereotyped, or relatively unchanging sequence behaviours.
  • Universal, because the same behaviour is found in every individual of the species.
  • Unaffected by learning, the same for every individual regardless of experience.
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Lea (1984) FAP features cont.

  • Ballistic, once the behaviour is triggered it follows an inevitable course and cannot be altered before it is completed.
  • Single purpose, the behaviour only occurs in a specific situation and not in any other.
  • A response to an identifiable specific sign stimulus, or, if it involves communication between members the same species, it is known as a releaser.
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Evaluation

  • It would appear that not all FAPs are fixed.
  • Hunt (1973) points out that sequences of behaviours that appear to be fixed and unchanging are in fact greatly influenced by environmental factors and learning experiences.
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  • Fixed action patterns are therefore more flexible than implied by the term 'fixed'.
  • Indeed many ethologists now prefer the term ‘modal action pattern’.
    • For example, a FAP is typically made up of several aggressive behaviours that form a series, and the duration of each behaviour varies from one individual animal to another, (even in the same animal from one encounter to another.)

IRMs and FAPs and the Male Stickleback

The function IRMs and FAPs can be seen in the example of the male stickleback.

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Male sticklebacks

  • Male sticklebacks are highly territorial during the spring mating season.
  • At this time they also develop a red spot on the underbelly.
  • If another male enters their territory, a sequence of highly stereotyped aggressive behaviours is initiated (FAP).
  • The sign stimulus that triggers the innate releasing mechanism is the site of the red spot.
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Tinbergen (1951)

  • Tinbergen (1951) presented sticklebacks with a series of wooden models of different shapes.
  • They found that if the model had a red spot, the stickleback would aggressively display and even attack it, regardless of shape.
  • If there was no red spot there was no aggression, even if the model looked realistically like a stickleback.
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Tinbergen (1951) findings

  • The researchers also found that these aggressive FAPs were unchanging from one encounter to another.
  • Once triggered, the FAP always ran its course to completion without any further stimulus.
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Evaluation

  • Ethological predictions are often drawn from animal studies and cannot be generalised to humans.
  • Lorenz did not study higher mammals such as primates, and Tinbergen did not study the kind of extreme and destructive violence that is common to human aggression.
  • However both made generalisations about aggressive behaviours in humans, including warfare.

Jump to other topics

1Social Influence

2Memory

3Attachment

4Psychopathology

5Approaches in Psychology

6Biopsychology

7Research Methods

8Issues & Debates in Psychology (A2 only)

9Option 1: Relationships (A2 only)

10Option 1: Gender (A2 only)

11Option 1: Cognition & Development (A2 only)

12Option 2: Schizophrenia (A2 only)

13Option 2: Eating Behaviour (A2 only)

14Option 2: Stress (A2 only)

15Option 3: Aggression (A2 only)

16Option 3: Forensic Psychology (A2 only)

17Option 3: Addiction (A2 only)

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