Tendency to act on a whim without considering consequences
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. Impulsive actions are typically "poorly conceived, prematurely expressed, unduly risky, or inappropriate to the situation that often result in undesirable consequences," which imperil long-term goals and strategies for success. Impulsivity can be classified as a multifactorial construct. 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." Thus, the construct of impulsivity includes at least two independent components: first, acting without an appropriate amount of deliberation, which may or may not be functional; and second, choosing short-term gains over long-term ones.
Impulsivity is both a facet of personality and a major component of various disorders, including FASD, ADHD, substance use disorders, bipolar disorder, antisocial personality disorder, and borderline personality disorder. Abnormal patterns of impulsivity have also been noted in instances of acquired brain injury and neurodegenerative diseases. Neurobiological findings suggest that there are specific brain regions involved in impulsive behavior, although different brain networks may contribute to different manifestations of impulsivity, and that genetics may play a role.
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. Compulsivity may be on a continuum with compulsivity on one end and impulsivity on the other, but research has been contradictory on this point. Compulsivity occurs in response to a perceived risk or threat, impulsivity occurs in response to a perceived immediate gain or benefit, 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.
Impulse.
An impulse is a wish or urge, particularly a sudden one. It can be considered as a normal and fundamental part of human thought processes, but also one that can become problematic, as in a condition like obsessive-compulsive disorder, borderline personality disorder, attention deficit hyperactivity disorder, or in fetal alcohol spectrum disorders.
The ability to control impulses, or more specifically control the desire to act on them, is an important factor in personality and socialization. Deferred gratification, also known as impulse control is an example of this, concerning impulses primarily relating to things that a person wants or desires. Delayed gratification comes when one avoids acting on initial impulses. Delayed gratification has been studied in relation to childhood obesity. Resisting the urge to act on impulses is important to teach children, because it teaches the value of delayed gratification.
 ;templatestyles src="Template:Blockquote/styles.css" / ;Many psychological problems are characterized by a loss of control or a lack of control in specific situations. Usually, this lack of control is part of a pattern of behavior that also involves other maladaptive thoughts and actions, such as substance abuse problems or sexual disorders like the paraphilias (e.g. pedophilia and exhibitionism). When loss of control is only a component of a disorder, it usually does not have to be a part of the behavior pattern, and other symptoms must also be present for the diagnosis to be made. (Franklin)
The five traits that can lead to impulsive actions.
For many years it was understood that impulsivity is a trait but with further analysis it can be found that there were five traits that can lead to impulsive actions:
positive urgency, 
negative urgency,
sensation seeking, 
lack of planning, and
lack of perseverance.
Associated behavioral and societal problems.
Attention-deficit hyperactivity disorder.
Attention deficit-hyperactivity disorder (ADHD) is a multiple component disorder involving inattention, impulsivity, and hyperactivity. The Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR) breaks ADHD into three subtypes according to the behavioral symptoms:
Attention-Deficit/Hyperactivity Disorder Predominantly Inattentive Type,
Attention-Deficit/Hyperactivity Disorder Predominantly Hyperactive-Impulsive Type, and
Attention-Deficit/Hyperactivity Disorder Combined Type.
Predominantly hyperactive-impulsive type symptoms may include
fidgeting and squirming in seats,
talking nonstop,
dashing around and touching or playing with anything in sight,
having trouble sitting still during dinner/school/story time,
being constantly in motion, and
having difficulty doing quiet tasks or activities.
Other manifestations primarily of impulsivity include
being very impatient, 
having difficulty waiting for things they want or waiting their turns in games, 
often interrupting conversations or others' activities, or
blurting out inappropriate comments, showing their emotions without restraint, and act without regard for consequences.
Prevalence of the disorder worldwide is estimated to be between 4% and 10%, with reports as low as 2.2% and as high as 17.8%. Variation in rate of diagnoses may be attributed to differences between populations (i.e. culture), and differences in diagnostic methodologies. Prevalence of ADHD among females is less than half that of males, and females more commonly fall into the inattentive subtype.
Despite an upward trend in diagnoses of the inattentive subtype of ADHD, impulsivity is commonly considered to be the central feature of ADHD, and the impulsive and combined subtypes are the major contributors to the societal costs associated with ADHD. The estimated cost of illness for a child with ADHD is $14,576 (in 2005 dollars) annually. Prevalence of ADHD among prison populations is significantly higher than that of the normal population.
In both adults and children, ADHD has a high rate of comorbidity with other mental health disorders such as learning disability, conduct disorder, anxiety disorder, major depressive disorder, bipolar disorder, and substance use disorders.
The precise genetic and environmental factors contributing to ADHD are relatively unknown, but endophenotypes offer a potential middle ground between genes and symptoms. ADHD is commonly linked to "core" deficits involving "executive function," "delay aversion," or "activation/arousal" theories that attempt to explain ADHD through its symptomology. Endophenotypes, on the other hand, purport to identify potential behavioral markers that correlate with specific genetic etiology. There is some evidence to support deficits in response inhibition as one such marker. Problems inhibiting prepotent responses are linked with deficits in pre-frontal cortex (PFC) functioning, which is a common dysfunction associated with ADHD and other impulse-control disorders.
Evidence-based psychopharmacological and behavioral interventions exist for ADHD.
Substance abuse.
Impulsivity appears to be linked to all stages of substance abuse.
The acquisition phase of substance abuse involves the escalation from single use to regular use. Impulsivity may be related to the acquisition of substance abuse because of the potential role that instant gratification provided by the substance may offset the larger future benefits of abstaining from the substance, and because people with impaired inhibitory control may not be able to overcome motivating environmental cues, such as peer pressure. "Similarly, individuals that discount the value of delayed reinforcers begin to abuse alcohol, marijuana, and cigarettes early in life, while also abusing a wider array of illicit drugs compared to those who discounted delayed reinforcers less."
Escalation or dysregulation is the next and more severe phase of substance abuse. In this phase individuals "lose control" of their addiction with large levels of drug consumption and binge drug use. Animal studies suggest that individuals with higher levels of impulsivity may be more prone to the escalation stage of substance abuse.
Impulsivity is also related to the abstinence, relapse, and treatment stages of substance abuse. People who scored high on the Barratt Impulsivity Scale (BIS) were more likely to stop treatment for cocaine abuse. Additionally, they adhered to treatment for a shorter duration than people that scored low on impulsivity. Also, impulsive people had greater cravings for drugs during withdrawal periods and were more likely to relapse. This effect was shown in a study where smokers that test high on the BIS had increased craving in response to smoking cues, and gave into the cravings more quickly than less impulsive smokers. Taken as a whole the current research suggests that impulsive individuals are less likely to abstain from drugs and more likely to relapse earlier than less impulsive individuals.
While it is important to note the effect of impulsivity on substance abuse, the reciprocating effect whereby substance abuse can increase impulsivity has also been researched and documented. The promoting effect of impulsivity on substance abuse and the effect of substance abuse on increased impulsivity creates a positive feedback loop that maintains substance seeking behaviors. It also makes conclusions about the direction of causality difficult. This phenomenon has been shown to be related to several substances, but not all. For example, alcohol has been shown to increase impulsivity while amphetamines have had mixed results.
Substance use disorder treatments include prescription of medications such as acamprosate, buprenorphine, disulfiram, LAAM, methadone, and naltrexone, as well as effective psychotherapeutic treatment like 
behavioral couples therapy, CBT, contingency management, motivational enhancement therapy, and relapse prevention.
Eating.
Impulsive overeating spans from an episode of indulgence by an otherwise healthy person to chronic binges by a person with an eating disorder.
Consumption of a tempting food by non-clinical individuals increases when self-regulatory resources are previously depleted by another task, suggesting that it is caused by a breakdown in self control. Impulsive eating of unhealthy snack foods appears to be regulated by individual differences in impulsivity when self-control is weak and by attitudes towards the snack and towards healthy eating when self-control is strong. There is also evidence that greater food consumption occurs when people are in a sad mood, although it is possible that this is due more to emotional regulation than to a lack of self-control. In these cases, overeating will only take place if the food is palatable to the person, and if so individual differences in impulsivity can predict the amount of consumption.
Chronic overeating is a behavioral component of binge eating disorder, compulsive overeating, and bulimia nervosa. These diseases are more common for women and may involve eating thousands of calories at a time. Depending on which of these disorders is the underlying cause, an episode of overeating can have a variety of different motivations. Characteristics common among these three disorders include low self-esteem, depression, eating when not physically hungry, preoccupation with food, eating alone due to embarrassment, and feelings of regret or disgust after an episode. In these cases, overeating is not limited to palatable foods.
Impulsivity differentially affects disorders involving the overcontrol of food intake (such as anorexia nervosa) and disorders involving the lack of control of food intake (such as bulimia nervosa). Cognitive impulsivity, such as risk-taking, is a component of many eating disorders, including those that are restrictive. However, only people with disorders involving episodes of overeating have elevated levels of motoric impulsivity, such as reduced response inhibition capacity.
One theory suggests that binging provides a short-term escape from feelings of sadness, anger, or boredom, although it may contribute to these negative emotions in the long-term. Another theory suggests that binge eating involves reward seeking, as evidenced by decreased serotonin binding receptors of binge-eating women compared to matched-weight controls and predictive value of heightened reward sensitivity/drive in dysfunctional eating.
Treatments for clinical-grade overeating include cognitive behavioral therapy to teach people how to track and change their eating habits and actions, interpersonal psychotherapy to help people analyze the contribution of their friends and family in their disorder, and pharmacological therapies including antidepressants and SSRIs.
Impulse buying.
Impulse buying consists of purchasing a product or service without any previous intent to make that purchase. It has been speculated to account for as much as eighty percent of all purchases in the United States.
There are several theories pertaining to impulsive buying. One theory suggests that it is exposure combining with the speed that a reward can be obtained that influences an individual to choose lesser immediate rewards over greater rewards that can be obtained later. For example, a person might choose to buy a candy bar because they are in the candy aisle even though they had decided earlier that they would not buy candy while in the store.
Another theory is one of self-regulation which suggests that the capacity to refrain from impulsive buying is a finite resource. As this capacity is depleted with repeated acts of restraint susceptibility to purchasing other items on impulse increases.
Finally, a third theory suggests an emotional and behavioral tie between the purchaser and the product which drives both the likelihood of an