-------------------------------------------------
Theories of impulsivity[edit]
Ego (cognitive) depletion[edit]
According to the ego (or cognitive) depletion theory of impulsivity, self-control refers to the capacity for altering one's own responses, especially to bring them into line with standards such as ideals, values, morals, and social expectations, and to support the pursuit of long-term goals.[74] Self-control enables a person to restrain or override one response, thereby making a different response possible.[74] A major tenet of the theory is that engaging in acts of self-control draws from a limited "reservoir" of self-control that, when depleted, results in reduced capacity for further self-regulation.[75][76] Self-control is viewed as analogous to a muscle: Just as a muscle requires strength and energy to exert force over a period of time, acts that have high self-control demands also require strength and energy to perform.[77] Similarly, as muscles become fatigued after a period of sustained exertion and have reduced capacity to exert further force, self-control can also become depleted when demands are made of self-control resources over a period of time. Baumeister and colleagues termed the state of diminished self-control strength ego depletion (or cognitive depletion).[76]
The strength model of self-control asserts that: * Just as exercise can make muscles stronger, there are signs that regular exertions of self-control can improve willpower strength.[78] These improvements typically take the form of resistance to depletion, in the sense that performance at self-control tasks deteriorates at a slower rate.[74] Targeted efforts to control behavior in one area, such as spending money or exercise, lead to improvements in unrelated areas, such as studying or household chores. And daily exercises in self-control, such as improving posture, altering verbal behavior, and using one's nondominant hand for simple tasks, gradually produce improvements in self-control as measured by laboratory tasks.[74] The finding that these improvements carry over into tasks vastly different from the daily exercises shows that the improvements are not due to simply increasing skill or acquiring self-efficacy from practice.[74] * Just as athletes begin to conserve their remaining strength when their muscles begin to tire, so do self-controllers when some of their self-regulatory resources have been expended. The severity of behavioral impairment during depletion depends in part on whether the person expects further challenges and demands.[74] When people expect to have to exert self-control later, they will curtail current performance more severely than if no such demands are anticipated.[79] * Consistent with the conservation hypothesis, people can exert self-control despite ego depletion if the stakes are high enough. Offering cash incentives or other motives for good performance counteracts the effects of ego depletion.[80] This may seem surprising but in fact it may be highly adaptive. Given the value and importance of the capacity for self-control, it would be dangerous for a person to lose that capacity completely, and so ego depletion effects may occur because people start conserving their remaining strength.[74] When people do exert themselves on the second task, they deplete the resource even more, as reflected in severe impairments on a third task that they have not anticipated.[79]
Empirical tests of the ego-depletion effect typically adopt dual-task paradigm.[75][81][82] Participants assigned to an experimental ego-depletion group are required to engage in two consecutive tasks requiring self-control.[77] Control participants are also required to engage in two consecutive tasks, but only the second task requires self-control. The strength model predicts that the performance of the experimental-group on the second self-control task will be impaired relative to that of the control group. This is because the finite self-control resources of the experimental participants will be diminished after the initial self-control task, leaving little to draw on for the second task.[74]
The effects of ego depletion do not appear to be a product of mood or arousal. In most studies, mood and arousal has not been found to differ between participants who exerted self-control and those who did not.[75][83] Likewise, mood and arousal was not related to final self-control performance.[83] The same is true for more specific mood items, such as frustration, irritation, annoyance, boredom, or interest as well. Feedback about success and failure of the self-control efforts does not appear to affect performance.[84] In short, the decline in self-control performance after exerting self-control appears to be directly related to the amount of self-control exerted and cannot be easily explained by other, well-established psychological processes.[83]
Automatic vs. controlled processes/cognitive control[edit]
Dual process theory states that mental processes operate in two separate classes: automatic and controlled. In general, automatic processes are those that are experiential in nature, occur without involving higher levels of cognition,[85] and are based on prior experiences or informal heuristics. Controlled decisions are effortful and largely conscious processes in which an individual weighs alternatives and makes a more deliberate decision.[citation needed] * Automatic Process: Automatic processes have four main features.[86] They occur unintentionally or without a conscious decision, the cost of the decision is very low in mental resources, they cannot be easily stopped, and they occur without conscious thought on the part of the individual making them. * Controlled Process: Controlled processes also have four main features[86] that are very close to the opposite in spectrum from their automatic counterparts. Controlled processes occur intentionally, they require the expenditure of cognitive resources, the individual making the decision can stop the process voluntarily, and the mental process is a conscious one.
Dual process theories at one time considered any single action/thought as either being automatic or controlled.[86] However, currently they are seen as operating more along a continuum as most impulsive actions will have both controlled and automatic attributes.[86] Automatic processes are classified according to whether they are meant to inhibit or to facilitate a thought process.[87] For example in one study[88] researchers offered individuals a choice between a 1:10 chance of winning a prize and a 10 in 100 chance. Many participants chose one of the choices over the other without identifying that the chances inherent in each were the same as they saw either only 10 chances total as more beneficial, or of having 10 chances to win as more beneficial. In effect impulsive decisions can be made as prior information and experiences dictate one of the courses of action is more beneficial when in actuality careful consideration would better enable the individual to make a more informed and improved decision.[citation needed]
Intertemporal choice[edit]
Intertemporal choice is defined as "decisions with consequences that play out over time".[89] This is often assessed using the relative value people assign to rewards at different points in time, either by asking experimental subjects to choose between alternatives or examining behavioral choices in a naturalistic setting.[citation needed]
Intertemporal choice is commonly measured in the laboratory using a "delayed discounting" paradigm, which measures the process of devaluing rewards and punishments that happen in the future.[89] In this paradigm, subjects must choose between a smaller reward delivered soon and a larger reward delivered at a delay in the future. Choosing the smaller-sooner reward is considered impulsive. By repeatedly making these choices, indifference points can be estimated. For example, if someone chose $70 now over $100 in a week, but chose the $100 in a week over $60 now, it can be inferred that they are indifferent between $100 in a week and an intermediate value between $60 and $70. A delay discounting curve can be obtained for each participant by plotting their indifference points with different reward amounts and time delays. Individual differences in discounting curves are affected by personality characteristics such as self-reports of impulsivity and locus of control; personal characteristics such as age, gender, IQ, race, and culture; socioeconomic characteristics such as income and education; and many other variables.[90] Lesions of the nucleus accumbens core subregion[91] or basolateral amygdala[92]produce shifts towards choosing the smaller-sooner reward, suggesting the involvement of these brain regions in the preference for delayed reinforcers. There is also evidence that the orbitofrontal cortex is involved in delay discounting, although there is currently debate on whether lesions in this region result in more or less impulsivity.[93]
Economic theory suggests that optimal discounting involves the exponential discounting of value over time. This model assumes that people and institutions should discount the value of rewards and punishments at a constant rate according to how delayed they are in time.[89] While economically rational, recent evidence suggests that this people and animals do not discount exponentially. Many studies suggest that humans and animals discount future values according to a hyperbolic discounting curve where the discount factor decreases with the length of the delay (for example, waiting from today to tomorrow involves more loss of value than waiting from twenty days to twenty-one days). Further evidence for non-constant delay discounting is suggested by the differential involvement of various brain regions in evaluating immediate versus delayed consequences. Specifically, the prefrontal cortex is activated when choosing between rewards at a short delay or a long delay, but regions associated with the dopamine system are additionally activated when the option of an immediate reinforcer is added.[94] Additionally, intertemporal choices differ from economic models because they involve anticipation (which may involve a neurological "reward" even if the reinforcer is delayed), self-control (and the breakdown of it when faced with temptations), and representation (how the choice is framed may influence desirability of the reinforcer),[89] none of which are accounted for by a model that assumes economic rationality.[citation needed]
One facet of intertemporal choice is the possibility for preference reversal, when a tempting reward becomes more highly valued than abstaining only when immediately available.[4] For example, when sitting home alone, a person may report that they value the health benefit of not smoking a cigarette over the effect of smoking one. However, later at night when the cigarette is immediately available, their subjective value of the cigarette may rise and they may choose to smoke it.[citation needed]
A theory called the "primrose path" is intended to explain how preference reversal can lead to addiction in the long run.[95] As an example, a lifetime of sobriety may be more highly valued than a lifetime of alcoholism, but, at the same time, one drink now may be more highly valued than not drinking now. 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,[96] 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).[citation needed]
Similarities between humans and non-human animals in intertemporal choice have been studied. Pigeons[97] and rats[98] also discount hyperbolically; tamarin monkeys do not wait more than eight seconds to triple the amount of a food reward.[99] 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.[citation needed]
Inhibitory control[edit]
Inhibitory control, often conceptualized as an executive function, is the ability to inhibit or hold back a prepotent response.[100] 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.[100] There is evidence that, in normal adults, commonly used behavioral measures of inhibitory control correlate with standard self-report measures of impulsivity.[101]
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.[102] Nigg developed a useful working taxonomy of these different types of inhibition, drawing heavily from the fields of cognitive and personality psychology[102]Nigg's eight proposed types of inhibition include the following:
Executive Inhibition[edit]
Interference control[edit]
Suppression of a stimulus that elicits an interfering response, enabling a person to complete the primary response. Interference control can also refer to suppressing distractors.[102]
Interference control has been measured using cognitive tasks like the stroop test, flanker tasks, dual task interference, and priming tasks.[103] Personality researchers have used the Rothbart effortful control measures and the conscientiousness scale of the Big Five as inventory measures of interference control. Based on imaging and neural research it is theorized that the anterior cingulate, the dorsolateral prefrontal/premotor cortex, and the basal ganglia are related to interference control.[104][105]
Cognitive inhibition[edit]
Cognitive inhibition is the suppression of unwanted or irrelevant thoughts to protect working memory and attention resources.[102]
Cognitive inhibition is most often measured through tests of directed ignoring, self-report on one's intrusive thoughts, and negative priming tasks. As with interference control, personality psychologists have measured cognitive inhibition using the Rothbart Effortful Control scale and the Big Five Conscientiousness scale. The anterior cingulate, the prefrontal regions, and the association cortex seem to be involved in cognitive inhibition.[102]
Behavioral inhibition[edit]
Behavioral Inhibition is the suppression of prepotent response.[102]
Behavioral inhibition is usually measures using the Go/No Go task, Stop signal task, and reports of suppression of attentional orienting. Surveys that are theoretically relevant to behavioral inhibition include the Rothbart effortful control scale, and the Big Five Conscientiousness dimension.[102] The rationale behind the use of behavioral measures like the Stop signal task is that "go" processes and "stop processes" are independent, and that, upon "go" and "stop" cues, they "race" against each other; if the go process wins the race, the prepotent response is executed, whereas if the stop processes wins the race, the response is withheld. In this context, impulsivity is conceptualized as a relatively slow stop process.[106] The brain regions involved in behavioral inhibition appear to be the lateral and orbital prefrontal regions along with premotor processes.
Oculomotor Inhibition[edit]
Oculomotor Inhibition is the effortful suppression of reflexive saccade.[102]
Oculomotor inhibition is tested using antisaccade and oculomotor tasks. Also, the Rothbart effortful control measure and the Big Five Conscientiousness dimension are thought to tap some of the effortful processes underlying the ability to suppress saccade. The frontal eye fields and the dorsolateral prefrontal cortex are involved in oculomotor inhibition.[102]
Motivational inhibition[edit]
In response to punishment[edit]
Motivational inhibition and response in the face of punishment can be measured using tasks tapping inhibition of primary response, modified go/no go tasks, inhibition of competing response, and emotional Stroop tasks.[102] Personality psychologists also use the Gray behavioral inhibition system measure, the Eysenck scale for neurotic introversion, and the Zuckerman Neuroticism-Anxiety scale.[102] The Septal-hippocampal formation, cingulate, and motor systems seem to be the brain areas most involved in response to punishment.[102]
In response to novelty[edit]
Response to novelty has been measured using the Kagan behavioral inhibition system measure and scales of neurotic introversion.[102] The amygdaloid system is implicated in novelty response.[102]
Automatic inhibition of attention[edit]
Recently inspected stimuli[edit]
Suppression of recently inspected stimuli for both attention and oculomotor saccade is usually measured using attentional and oculomotor inhibition of return tests. The superior colliculus and the midbrain, oculomotor pathway are involved in suppression of stimuli.[102]
Neglected stimuli[edit]
Information at locations that are not presently being attended to is suppressed, while attending elsewhere.[102]
This involves measures of covert attentional orienting and neglect, along with personality scales on neuroticism.[102] The posterior association cortex and subcortical pathways are implicated in this sort of inhibition.[102]