butterfly effect

the tendency of a complex, dynamic system to be sensitive to initial conditions, so that over time a small cause may have large, unpredictable effects (see sensitive dependence). The term refers to an example in which the fluttering of the wings of a butterfly in one part of the world is seen to contribute to the causation of a tornado in another. The term is used in chaos theory and more generally to describe nonlinear causal connections.

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Psychology term of the day

February 17th 2025

sexually dimorphic nucleus

a nucleus of the central nervous system that differs in size between males and females. In humans, for example, a nucleus in the medial preoptic area of the hypothalamus that synthesizes gonadotropin-releasing hormone tends to be larger and more active in males than in females because gonadotropin release is continuous (it is cyclical in females). In songbirds whose males sing more than females, several brain nuclei associated with both song learning and song production are larger in males than in females.