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[[Image:Catyawn.jpg|right|thumb|Yawning]]
Another well known case is the classic experiments by Tinbergen and [[Konrad Lorenz|Lorenz]] on the [[graylag goose]]. Like similar [[waterfowl]], it will roll a displaced [[Egg (biology)|egg]] near its nest back to the others with its beak. The sight of the displaced egg triggers this mechanism. If the egg is taken away, the animal continues with the behavior, pulling its head back as if an imaginary egg is still being maneuvered by the underside of its beak. However, it will also attempt to move other egg shaped objects, such as a golf ball, door knob, or even an egg too large to have possibly been laid by the goose itself (a [[supernormal stimulus]]).<ref>[[Niko Tinbergen|Tinbergen, N.]] (1951) ''The Study of Instinct''. Oxford University Press, New York.</ref>
Although fixed action patterns are most common in animals with simpler cognitive capabilities, humans also demonstrate fixed action patterns. For example, infants grasp strongly with their hands as a response to tactile stimulus. This is thought to be a [[vestigiality|vestigial mechanism]] where when threatened by a predator a young primate would grab on to a parent's fur so the parent could climb to safety without having to hold its child{{Fact|date=May 2007}} (see also [[reflex action]]). Another FAP shared by some animals, including humans, is [[yawning]], which often triggers yawning in other individuals. Yawns last around 6 seconds and are difficult to stop once initiated. Yawning, whether seen, heard or both, then serves as a releaser in nearby animals.<ref>Provine, R. R. (1986) Yawning as a stereo-typed action pattern and releasing stimulus. ''[[Ethology (journal)|Ethology]]'' 72:109-122.</ref>
==Exploitation of FAPs==
Some species have evolved to exploit the fixed action patterns of other species. Replicating the releasing mechanism required to trigger an FAP is known as '''code-breaking'''. A well known example of this is [[brood parasitism]], where one species will lay its eggs in the nest of another species, which will then parent its young. A young [[North American cowbird]], for example, provides a supernormal stimulus to its parent, which will cause it to forage rapidly in order to satisfy the larger bird's demands.<ref>Wickler, W. (1968) ''Mimicry in Plants and Animals.'' World University Library, London.</ref> In a natural situation a nestling will provide higher levels of stimulus with noisier, more energetic behavior, communicating its urgent need for food. Parents in this situation should work extra hard to provide food, otherwise their offspring are likely to die of [[starvation]].
==See also==
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