Fixed action pattern

"Fixed action pattern" is an ethological term describing an instinctive behavioral sequence that is highly stereotyped and species-characteristic.^[1] Fixed action patterns are said to be produced by the innate releasing mechanism, a "hard-wired" neural network, in response to a sign/key stimulus or releaser.^[1][2] Once released, a fixed action pattern runs to completion.^[1]

This term is often associated with Konrad Lorenz, who is the founder of the concept.^[1] Lorenz identified six characteristics of fixed action patterns.^[3] These characteristics state that fixed action patterns are stereotyped, complex, species-characteristic, released, triggered, and independent of experience.^[3]

Fixed action patterns have been observed in many species, but most notably in fish and birds.^[1][2] Classic studies by Konrad Lorenz and Niko Tinbergen involve male stickleback mating behavior and greylag goose egg-retrieval behavior.^[4][5]

Fixed action patterns have been shown to be evolutionarily advantageous, as they increase both fitness and speed.^[6] However, as a result of their predictability, they may also be used as a means of exploitation. An example of this exploitation would be brood parasitism.^[7]

There are four exceptions to fixed action pattern rules:^[8] reduced response threshold, vacuum activity, displacement behavior, and graded response.^[8]