Ethology - Instinct

Instinct

The Merriam-Webster dictionary defines instinct as a largely inheritable and unalterable tendency of an organism to make a complex and specific response to environmental stimuli without involving reason. For ethologists, instinct means a series of predictable behaviors for fixed action patterns. Such schemes are only acted when a precise stimulating signal is present. When such signals act as communication among members of the same species, they are known as releasers. A notable example of a releaser is the beak movements in many bird species performed by the newly-hatched chicks, which stimulates the mother's regurgitating process to feed her offspring. Another well-known case is the classic experiments by Tinbergen on the Graylag Goose. Like similar waterfowl, the goose rolls a displaced 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 behaviour, pulling its head back as if an imaginary egg is still being maneuvered by the underside of its beak. However, it also attempts to move other egg-shaped objects, such as a giant plaster egg, door knob, or even a volleyball back into the nest. Such objects, when they exaggerate the releasers found in natural objects, can elicit a stronger version of the behavior than the natural object, so that the goose ignores its own displaced egg in favor of the giant dummy egg. These exaggerated releasers for instincts were named supernormal stimuli by Tinbergen. Tinbergen found he could produce supernormal stimuli for most instincts in animals—such as cardboard butterflies that male butterflies preferred to mate with if they had darker stripes than a real female, or dummy fish that a territorial male stickleback fish fought more violently than a real invading male if the dummy had a brighter-colored underside. Harvard psychologist Deirdre Barrett has done research pointing out how easily humans also respond to supernormal stimuli for sexual, nurturing, feeding, and social instincts. However, a behaviour only made of fixed action patterns would be particularly rigid and inefficient, reducing the probability of survival and reproduction, so the learning process has great importance, as does the ability to change the individual's responses based on its experience. It can be said that the more the brain is complex and the life of the individual long, the more its behaviour is "intelligent" (in the sense of being guided by experience rather than stereotyped FAPs).