

Involuntary response by an animal, resulting in a predictable and relatively fixed behaviour pattern. Instinctive behaviour is an inherited mechanism that serves to promote the survival of an animal or species. It is most apparent in fighting and sexual activity. The simplest form is the reflex. All animals have instinct, but, in general, the higher the animal form, the more flexible the behaviour. Among mammals, learned behaviour often prevails over instinctive behaviour.

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Instinct is the inherent disposition of a living organism toward a particular behavior. Instincts are unlearned, inherited fixed action patterns of responses or reactions to certain kinds of stimuli. Examples of instinctual fixed action patterns can be observed in the behavior of animals, which perform various activities (sometimes complex) that are not based upon prior experience and do not depend on emotion or learning, such as reproduction, and feeding among insects. Other examples include animal fighting, animal courtship behavior, internal escape functions, and building of nests.

Instinctual actions - in contrast to actions based on learning which is served by memory and which provides individually stored successful reactions built upon experience - have no learning curve, they are hard-wired and ready to use without learning, but do depend on maturational processes to appear.

Biological predispositions are innate biologically vectored behaviors that can be easily learned. For example in one hour a baby colt can learn to stand, walk, and run with the herd of horses. Learning is required to fine tune the neurological wiring reflex like behavior. True reflexes can be distinguished from instincts by their seat in the nervous system; reflexes are controlled by spinal or other peripheral ganglion, but instincts are the province of the brain.


Technically speaking, any event that initiates an instinctive behavior is termed a key stimulus (KS) or a releasing stimulus. Key stimuli in turn lead to innate releasing mechanisms (IRM), which in turn produce fixed action patterns (FAP). More than one key stimulus may be needed to trigger a FAP. Sensory receptor cells are critical in determining the type of FAP which is initiated. For instance, the reception of pheromones through nasal sensory receptor cells may trigger a sexual response, while the reception of a "frightening sound" through auditory sensory receptor cells may trigger a fight or flight response. The neural networks of these different sensory cells assist in integrating the signal from many receptors to determine the degree of the KS and therefore produce an appropriate degree of response. Several of these responses are determined by carefully regulated chemical messengers called hormones. The endocrine system, which is responsible for the production and transport of hormones throughout the body, is made up of many secretory glands that produce hormones and release them for transport to target organs. Specifically in vertebrates, neural control of this system is funneled through the hypothalamus to the anterior and posterior pituitary gland. Whether or not the behavioral response to a given key stimuli is either learned, genetic, or both is the center of study in the field of behavioural genetics. Researchers use techniques such as inbreeding and knockout studies to separate learning and environment from genetic determination of behavioral traits. The definitions of what constitutes instinct in humans beyond infancy is conjectural. It could be said that as well as obvious instincts such as breathing, sex-drive, desire to communicate, etc., humans also have an instinct toward knowledge. The will to invent solutions to requirements, to present self and possessions aesthetically and to be organised economically, culturally, religiously and politically could be described as instincts to promote survival, which are further enhanced by learning which is not instinctive.



Instinctive behavior can be demonstrated across much of the broad spectrum of animal life. According to Darwin's theory of evolution by natural selection, a favorable trait, such as an instinct, will be selected for through competition and improved survival rate of life forms possessing the instinct. Thus, for evolutionary biology, instincts can be explained in terms of behaviors that favor survival.


The Baldwin Effect




Scientific definition


Any repeated behavior can be called "instinctual." As can any behavior for which there is a strong innate component. However, to distinguish behavior beyond the control of the organism from behavior that has a repetitive component we can turn to the book "Instinct"(1961) stemming from the 1960 conference. A number of criteria were established which distinguishes instinctual from other kinds of behavior. To be considered instinctual a behavior must a) be automatic, b) be irresistible, c) occur at some point in development, d) be triggered by some event in the environment, e) occur in every member of the species, f) be unmodifiable, and g) govern behavior for which the organism needs no training (although the organism may profit from experience and to that degree the behavior is modifiable). The absence of one or more of these criteria indicates that the behavior is not fully instinctual. Instincts do exist in insects and animals as can be seen in behaviors that can not be changed by learning. Psychologists do recognize that humans do have biological predispositions or behaviors that are easy to learn due to biological wiring, for example walking and talking.

If these criteria are used in a rigorous scientific manner, application of the term "instinct" cannot be used in reference to human behavior. When terms, such as mothering, territoriality, eating, mating, and so on, are used to denote human behavior they are seen to not meet the criteria listed above. In comparison to animal behavior such as hibernation, migration, nest building, mating and so on that are clearly instinctual, no human behavior meets the necessary criteria. And even in regard to animals, in many cases if the correct learning is stopped from occurring these instinctual behaviors disappear, suggesting that they are potent, but limited, biological predispostions. In the final analysis, under this definition, there are no human instincts.

In humans



Additional human traits that have been looked at as instincts are: sleeping, altruism, disgust, face perception, language acquisitions, "fight or flight" and "subjugate or be subjugated". Some experiments in human and primate societies have also come to the conclusion that a sense of fairness could be considered instinctual, with humans and apes willing to harm their own interests in protesting unfair treatment of self or others.


See also


Beach, F. A. The descent of instinct. Psychol. Rev. 62:401-10.

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