In this procedure, responses that occur before a set time interval has passed are not reinforced and reset the time required between behaviors.In a study, a child was taken to the experimental room and told that they were going to play a game in which they had a chance to win a lot of M&Ms. Every time they made the light of the reward indicator by pressing a red button, they would earn an M&Ms. However, they had to wait a while (6 seconds) before they could press it to get another point. If they had pressed the button too soon, then they would have not gotten a point, and the light would not go on, and they had to wait a while before they could press it to get another point.Researchers have also observed that subjects in a time-based situation will often engage in a sequence or chain of behaviors between reinforceable responses. This is because this collateral behavior sequence helps the subject "wait out" the required temporal delay between responses. Other
Other common impulsivity tasks include the Continuous performance task (CPT), 5-choice serial reaction time task (5-CSRTT), Stroop task, and Matching Familiar Figures Task. Pharmacology and neurobiology
Neurobiological findings
Although the precise neural mechanisms underlying disorders of impulse control are not fully known, the prefrontal cortex (PFC) is the brain region most ubiquitously implicated in impulsivity. Damage to the prefrontal cortex has been associated with difficulties preparing to act, switching between response alternatives, and inhibiting inappropriate responses.
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.