In psychology, impulsivity (or impulsiveness) is a tendency to act on a whim, displaying behavior characterized by little or no forethought, reflection, or consideration of the consequences

.[1] Impulsive actions are typically “poorly conceived, prematurely expressed, unduly risky, or inappropriate to the situation that often result in undesirable consequences,

[2] which imperil long-term goals and strategies for success.

[3] Impulsivity can be classified as a multifactorial construct.

[4] A functional variety of impulsivity has also been suggested, which involves action without much forethought in appropriate situations that can and does result in desirable consequences. “When such actions have positive outcomes, they tend not to be seen as signs of impulsivity, but as indicators of boldness, quickness, spontaneity, courageousness, or unconventionality”[2]

[5] Thus, the construct of impulsivity includes at least two independent components: first, acting without an appropriate amount of deliberation,[2] which may or may not be functional; and second, choosing short-term gains over long-term ones.[6]

Impulsivity is both a facet of personality and a major component of various disorders, including FASD, ADHD,[7] substance use disorders,[8]

[9] bipolar disorder,[10] antisocial personality disorder,[11] and borderline personality disorde

r.[10] Abnormal patterns of impulsivity have also been noted instances of acquired brain injury[12] and neurodegenerative diseases.[13] Neurobiological findings suggest that there are specific brain regions involved in impulsive behavior,[14][15][16] although different brain networks may contribute to different manifestations of impulsivity,[17] and that genetics may play a role.[18]

Many actions contain both impulsive and compulsive features, but impulsivity and compulsivity are functionally distinct. Impulsivity and compulsivity are interrelated in that each exhibits a tendency to act prematurely or without considered thought and often include negative outcomes.[19

][20] Compulsivity may be on a continuum with compulsivity on one end and impulsivity on the other, but research has been contradictory on this point.[21] Compulsivity occurs in response to a perceived risk or threat, impulsivity occurs in response to a perceived immediate gain or benefit,[19] and, whereas compulsivity involves repetitive actions, impulsivity involves unplanned reactions.

Impulsivity is a common feature of the conditions of gambling and alcohol addiction. Research has shown that individuals with either of these addictions discount delayed money at higher rates than those without, and that the presence of gambling and alcohol abuse lead to additive effects on discounting.[22]