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 impulsive purchase as well as the degree that a person will retroactively be satisfied with that purchase result. Some studies have shown a large number of individuals are happy with purchases made on impulse (41% in one study) which is explained as a preexisting emotional attachment which has a positive relationship both with the likelihood of initiating the purchase as well as mitigating post purchase satisfaction.
Because it is always "now," the drink is always chosen, and a paradoxical effect occurs whereby the more-valued long-term alternative is not achieved because the more-valued short-term alternative is always chosen. This is an example of complex ambivalence, when a choice is made not between two concrete alternatives but between one immediate and tangible alternative (i.e. having a drink) and one delayed and abstract alternative (i.e. sobriety). Similarities between humans and non-human animals in intertemporal choice have been studied. Pigeons and rats also discount hyperbolically; tamarin monkeys do not wait more than eight seconds to triple the amount of a food reward. The question arises as to whether this is a difference of homology or analogy—that is, whether the same underlying process underlies human-animal similarities or whether different processes are manifesting in similar patterns of results. Inhibitory control
Inhibitory control, often conceptualized as an executive function, is the ability to inhibit or hold back a prepotent response. It is theorized that impulsive behavior reflects a deficit in this ability to inhibit a response; impulsive people may find it more difficult to inhibit action whereas non-impulsive people may find it easier to do so. There is evidence that, in normal adults, commonly used behavioral measures of inhibitory control correlate with standard self-report measures of impulsivity.Inhibitory control may itself be multifaceted, evidenced by numerous distinct inhibition constructs that can be measured in different ways, and relate to specific types of psychopathology.