Effects of the storage conditions on the stability of natural and synthetic cannabis in biological matrices for forensic toxicology analysis: An update from the literature

Self-control is an aspect of inhibitory control, one of the core executive functions.^[1][2] Executive functions are cognitive processes that are necessary for regulating one's behavior in order to achieve specific goals.^[1][2] Defined more independently, self-control is the ability to regulate one's emotions, thoughts, and behavior in the face of temptations and impulses.^[3] Thought to be like a muscle, acts of self-control expend a limited resource. In the short term, overuse of self-control leads to the depletion of that resource.^[4] However, in the long term, the use of self-control can strengthen and improve the ability to control oneself over time.^[3][5]

A related concept in psychology is emotional self-regulation.^[6]

Self-control is also a key concept in the general theory of crime, a major theory in criminology. The theory was developed by Michael Gottfredson and Travis Hirschi in their book A General Theory of Crime (1990). Gottfredson and Hirschi define self-control as the differentiating tendency of individuals to avoid criminal acts independent of the situations in which they find themselves.^[7] Individuals with low self-control tend to be impulsive, inconsiderate towards others, risk takers, short-sighted, and nonverbal oriented. About 70% of the variance in questionnaire data operationalizing one construct of self-control was found to be genetic.^[8]

Classically, the virtue of self-control was usually called "continence" and was contrasted with the vice of akrasia or incontinence. "Willpower" is another common synonym.

Sometimes self-control under particular temptations was subsumed by other virtues. For example, self-control in fearful situations as courage, or self-control when angry as good temper.

Christians may describe the struggle with akrasia as a battle between spirit (which is inclined to God) and flesh (which is mired in sin). Jesus, as his crucifixion approached, felt himself recoil from this task, and noticed "the spirit indeed is willing, but the flesh is weak".^[9] Paul the Apostle, in his letter to the Romans, complained, "I do not understand my own actions. For I do not do what I want, but I do the very thing I hate.... I know that the good does not dwell within me, that is, in my flesh. For the desire to do the good lies close at hand, but not the ability".^[10] St. Augustine wrote in his Confessions, "As a youth I prayed, 'Give me chastity and continence, but not right away.'"^[11]

The related virtue of temperance, or sophrosyne, has been discussed by philosophers and religious thinkers from Plato and Aristotle to the present day. One of the earliest and most well-known examples of self control as a virtue was Aristotle's virtue of temperance, which concerns having a well-chosen and well-regulated set of desires. The vices associated with Aristotle's temperance are self-indulgence (deficiency) and insensibility (excess). Deficiency or excess is in reference to how much temperance is had, for example, a deficiency of temperance leads to over indulgence, while too much or an excess of temperance leads to insensibility or unreasonable control. Aristotle suggested this analogy: The intemperate person is like a city with bad laws; the person without self-control is like a city that has good laws on the books but that does not enforce them.^[12]

Desire is an affectively charged motivation toward a certain object, person, or activity, often, but not limited to, one associated with pleasure or relief from displeasure.^[13] Desires differ in their intensity and longevity.A desire becomes a temptation when it impacts or enters the individual's area of self-control, if the behavior resulting from the desire conflicts with an individual's values or other self-regulatory goals.^[14][15] A limitation to research on desire is that people desire different things. In research into what people desire in real world settings, over one week 7,827 self-reports of desires were collected, including differences in desire frequency and strength, degree of conflict between desires and other goals, and the likelihood of resisting desire and success of the resistance. The most common and strongly experienced desires are those related to bodily needs like eating, drinking, and sleeping.^[15][16]

Self-control dilemmas occur when long-term goals clash with short-term outcomes. Counteractive Self-Control Theory states that when presented with such a dilemma, we lessen the significance of the instant rewards while momentarily increasing the importance of our overall values.^[17] When asked to rate the perceived appeal of different snacks before making a decision, people valued health bars over chocolate bars. However, when asked to do the rankings after having chosen a snack, there was no significant difference of appeal.^[18] Further, when college students completed a questionnaire prior to their course registration deadline, they ranked leisure activities as less important and enjoyable than when they filled out the survey after the deadline passed. The stronger and more available the temptation is, the harsher the devaluation will be.^[19]

One of the most common self-control dilemmas involves the desire for unhealthy or unneeded food consumption versus the desire to maintain long-term health. An indication of unneeded food could also be over-expenditure on certain types of consumption such as eating away from home. Not knowing how much to spend, or overspending one's budget on eating out, can be a symptom of a lack of self-control.^[20]

Experiment participants rated a new snack as significantly less healthy when it was described as very tasty compared to when they heard it was just slightly tasty. Without knowing anything else about a food, the mere suggestion of good taste triggered counteractive self-control and prompted them to devalue the temptation in the name of health. Further, when presented with the strong temptation of one large bowl of chips, participants both perceived the chips to be higher in calories and ate less of them than did participants who faced the weak temptation of three smaller chip bowls, even though both conditions represented the same amount of chips overall.^[21]

Weak temptations are falsely perceived to be less unhealthy, so self-control is not triggered and desirable actions are more often engaged in; this supports the counteractive self-control theory.^[22] Weak temptations present more of a challenge to overcome than strong temptations, because they appear less likely to compromise long-term values.^[18][19]

The decrease in an individual's liking of and desire for a substance following repeated consumption of that substance is known as satiation. Satiation rates when eating depend on interactions of trait self-control and healthiness of the food. After eating equal amounts of either clearly healthy (raisins and peanuts) or unhealthy (M&Ms and Skittles) snack foods, people who scored higher on trait self-control tests reported feeling significantly less desire to eat more of the unhealthy foods than they did the healthy foods. Those with low trait self-control satiated at the same pace regardless of health value.

Further, when reading a description emphasizing the sweet flavor of their snack, participants with higher trait self-control reported a decrease in desire faster than they did after hearing a description of the healthy benefits of their snack. Once again, those with low self-control satiated at the same rate regardless of the description. Perceived unhealthiness of the food alone, regardless of actual health level, relates to faster satiation, but only for people with high trait self-control.^[23]

Thinking that is characterized by high construals, whenever individuals "are obliged to infer additional details of content, context, or meaning in the actions and outcomes that unfold around them",^[24] will view goals and values in a global, abstract sense, whereas low-level construals emphasize concrete, definitive ideas and categorizations. Different construal levels determine our activation of self-control in response to temptations.

One technique for inducing high-level construals is asking an individual a series of "why?" questions that lead to increasingly abstracted responses, whereas low-level construals are induced by "how?" questions leading to increasingly concrete answers. When taking an Implicit Association Test, people with induced high-level construals are significantly faster at associating temptations (such as candy bars) with "bad", and healthy choices (such as apples) with "good" than those in the low-level condition. Those with induced higher-level construals also show a significantly increased likelihood of choosing an apple for snack over a candy bar. In a person who is not exercising any conscious or active self-control efforts, temptations can be dampened by merely inducing high-level construals in them. Abstraction of high-level construals may remind people of their large-scale values, such as a healthy lifestyle, which deemphasizes the current tempting situation.^[15][25]

Positive correlation between linguistic capability and self-control has been inferred from experiments with common chimpanzees.^[26]

Human self-control research is typically modeled by using a token economy system: a behavioral program in which individuals in a group can earn tokens for a variety of desirable behaviors and can cash in the tokens for various backup, positive reinforcers.^[27]: 305 The difference in research methodologies with humans using tokens or conditioned reinforcers versus non-humans using sub-primary forces^[jargon] suggested procedural artifacts as a possible suspect^[specify]. One procedural difference was in the delay in the exchange period:^[28] Non-human subjects can and most likely would access their reinforcement immediately; human subjects had to wait for an "exchange period" in which they could exchange their tokens for money, usually at the end of the experiment. When this was done with non-human subjects (pigeons), they responded much like humans in that males showed much less control than females.^[29]

Logue,^[30] who is discussed more below, points out that in her study on self-control it was boys who responded with less self-control than girls. She says that in adulthood, for the most part, the sexes equalize on their ability to exhibit self-control. This could imply a human's ability to exert more self-control as they mature and become aware of the consequences associated with impulsivity. This suggestion is further examined below.

Most of the research in the field of self-control assumes that self-control is, in general, better than impulsiveness. As a result, almost all research done on this topic is from this standpoint; very rarely is impulsiveness the more adaptive response in experimental design.^{[citation needed]}

Some in the field of developmental psychology think of self-control in a way that takes into account that sometimes impulsiveness is the more adaptive response. In their view, a normal individual should have the capacity to be either impulsive or controlled depending on which is the most adaptive. However, there is comparatively less research conducted along these lines.^[30]

Self-control has been theorized to be a measurable variable in humans, although there are many different tests and means of measuring it.^[31] In the worst circumstances people with the most self-control and resilience have the best chance of defying the odds they are faced with, such as poverty, bad schooling, unsafe communities, etc.^{[citation needed]} Those at a disadvantage but with high self-control go on to higher education, professional jobs, and psychosocial outcomes, although there is conflicting evidence on health impacts later in adulthood.^[32][33]

The psychological phenomenon known as "John Henryism" posits that when goal-oriented, success-minded people strive ceaselessly in the absence of adequate support and resources, they can—like the eponymous 19th-century folk hero who fell dead of an aneurysm after besting a steam-powered drill in a railroad-spike-driving competition—work themselves to death (or toward it). In the 1980s, socio-epidemiologist Sherman James found that black Americans in North Carolina suffered disproportionately from heart disease and strokes. He suggested "John Henryism" as the cause of this phenomenon.^[34]

Using compassion, gratitude, and healthy pride to create positive emotional motivation can be less stressful, less vulnerable to rationalization, and more likely to succeed than the traditional strategy of using logic and willpower to suppress behavior that resonates emotionally.^[35]

Philosopher Immanuel Kant, at the beginning of one of his main works, "Groundwork of the Metaphysics of Morals", mentions the term "Selbstbeherrschung"—self-control—in a way such that it does not play a key role in his account of virtue. He argues instead that qualities such as self-control and moderation of affect and passions are mistakenly taken to be absolutely good (G 4: 394).^[36] In his apology of a solid^{[clarification needed]} universal morality, he also saw compassion as a weak and misguided sentiment: "Such benevolence is called soft-heartedness and should not occur at all among human beings", he said of it.^[relevant?] In distancing from his previous positions on the matter of self-control, he points out that such qualities can have only instrumental value: they can promote the good will and make its work easier, but they can also have bad effects. In a distinction between moral and self-control^{[needs copy edit]}, Kant mentions the example of the cruel Roman Dictator Lucius Cornelius Sulla Felix: despite his maxims being morally incorrect, Sulla had self-control because he steadfastly followed those maxims (A 7: 293)^{[full citation needed]}. Sulla lacks the two levels of moral self-control that are constitutive of virtue (our ability to adopt moral maxims, abstracted from sense impressions; and our ability to follow these maxims). His lack of virtue is primarily explained by his failure to compel himself to adopt moral maxims. According to Kant, self-control is merely a kind of instrument for following already-adopted maxims. As a result, even when closer attention is paid to self-control, its role in adopting morally correct maxims remains neglected in Kant's secondary literature^{[clarification needed]}.^[37]

B.F. Skinner's Science and Human Behavior provides a survey of nine categories of self-control methods.^[38]

The manipulation of the environment to make some responses easier to physically execute and others more difficult illustrates this principle. This can be physical guidance: the application of physical contact to induce an individual to go through the motions of a desired behavior. This can also be a physical prompt.^[27] Examples of this include clapping one's hand over one's own mouth, placing one's hand in one's pocket to prevent fidgeting, and using a 'bridge' hand position to steady a pool shot; these all represent physical methods to affect behavior.^[38]: 231

Manipulating the occasion for behavior may change behavior as well. Removing distractions that induce undesired actions or adding a prompt to induce them are examples. Hiding temptation and leaving reminders are two more.^[38]: 233 The need to hide temptation is a result of temptation's effect on the mind.

A common theme among studies of desire is an investigation of the underlying cognitive processes of a craving for an addictive substance, such as nicotine or alcohol. In order to better understand the cognitive processes involved, the Elaborated Intrusion (EI) theory of craving was developed. According to EI, craving persists because individuals develop mental images of the coveted substance that are themselves pleasurable, but which also increase their awareness of deficit.^[39][15] The result is a cruel circle of desire, imagery, and preparation to satisfy the desire. This quickly escalates into greater expression of the imagery that incorporates working memory, interferes with performance on simultaneous cognitive tasks, and strengthens the emotional response. Essentially the mind is consumed by the craving for a desired substance, and this craving in turn interrupts any concurrent cognitive tasks.^[39][15] A craving for nicotine or alcohol is an extreme case, but EI theory also applies to more ordinary motivations and desires.

Deprivation is the time in which an individual does not receive a reinforcer; satiation occurs when an individual has received a reinforcer to such a degree that it temporarily has no reinforcing power.^[27]: 40 If we deprive ourselves of a stimulus, the value of that reinforcement increases.^[40] For example, if a person has been deprived of food, they may go to extreme measures to get that food, such as stealing. On the other hand, if a person eats a large meal, they may no longer be enticed by the reinforcement of dessert.

One may manipulate one's own behavior by affecting states of deprivation or satiation. By skipping a meal before a free dinner one may more effectively capitalize on the free meal. By eating a healthy snack beforehand the temptation to eat free "junk food" is reduced.^[38]: 235

Imagery is important in desire cognition during a state of deprivation. One study divided smokers divided into two groups: The control group was instructed to continue smoking as usual until they arrived at the laboratory, where they were then asked to read a multisensory neutral script (one not related to a craving for nicotine). The experimental group, however, was asked to abstain from smoking before coming to the laboratory in order to induce craving, and upon their arrival were told to read a multisensory urge-induction script intended to intensify their nicotine craving.^[15][41] After the participants finished reading the script they rated their craving for cigarettes. Next they formulated visual or auditory images when prompted with verbal cues such as "a game of tennis" or "a telephone ringing". After this task the participants again rated their craving for cigarettes. The study found that the craving experienced by the abstaining smokers was decreased to the control group's level by visual imagery but not by auditory imagery alone.^[15][41] That mental imagery served to reduce the level of craving in smokers suggests that it can be used as a method of self-control during times of deprivation.

Manipulating emotional conditions can induce certain ways of responding.^[42] One example of this can be seen in theatre. Actors often elicit tears from their own painful memories if it is necessary for the character they are playing to cry. One may read a letter or book, listen to music, or watch a movie, in order to get in the proper state of mind for a certain event or function.^[27] Additionally, considering an activity either as "work" or as "fun" can have an effect on the difficulty of self-control.^[43]

To analyze the possible effects of the cognitive transformation of an object on desire, a study was conducted on 71 undergraduate students, all of whom were familiar with a particular chocolate product. The participants were randomly assigned to one of three groups: the control condition, the consummatory condition, and the nonconsummatory transformation condition.^[15][44] Each group was then given three minutes to complete their assigned task. The participants in the control condition were told to read a neutral article, about a location in South America, that was devoid of any words associated with food consumption. Those in the consummatory condition were instructed to imagine as clearly as possible how consuming the chocolate would taste and feel. The participants in the nonconsummatory transformation condition were told to imagine as clearly as possible odd settings or uses for the chocolate. Next, all the participants underwent a manipulation task that required them to rate their mood on a five-point scale in response to ten items they viewed. Following the manipulation task, participants completed automatic evaluations that measured their reaction time to six different images of the chocolate, each of which was paired with a positive or a negative stimuli. The results showed that the participants instructed to imagine the consumption of the chocolate demonstrated higher^[specify] automatic evaluations toward the chocolate than did the participants told to imagine odd settings or uses for the chocolate, and participants in the control condition fell in-between the two experimental conditions.^[15][44] This indicates that the manner in which one considers an item influences how much it is desired.

Aversive stimulation is used as a means of increasing or decreasing the likelihood of target behavior.^[42] An averse stimuli is sometimes referred to as a "punisher" or an "aversive".^[27] Closely related to the idea of a punisher is the concept of punishment. Punishment is when in some situation, a person does something that is immediately followed by a punisher; that person then is less likely to do the same thing again in a similar situation. An example of this can be seen when a teenager stays out past curfew, the teenager's parents ground the teenager, and this punishment makes it less likely that the teenager will stay out past their curfew again.

Low doses of stimulants, such as methylphenidate and amphetamine, improve inhibitory control and are used to treat ADHD.^[45] High amphetamine doses that are above the therapeutic range can interfere with working memory and other aspects of inhibitory control.^[46][47] Alcohol impairs self-control.^[48]

Operant conditioning, sometimes referred to as Skinnerian conditioning, is the process of strengthening a behavior by reinforcing it or weakening it by punishing it.^[42] By continually strengthening and reinforcing a behavior, or weakening and punishing a behavior, an association as well as a consequence develops. A behavior that is altered by its consequences is known as operant behavior.^[27] There are multiple components of operant conditioning. These include reinforcement such as positive reinforcers and negative reinforcers. A positive reinforcer is a stimulus which, when presented immediately following a behavior, causes the behavior to increase in frequency. Negative reinforcers are stimuli whose removal immediately after a response cause the response to be strengthened or to increase in frequency. Components of punishment are also incorporated such as positive punishment and negative punishment.^[27] Examples of operant conditioning are commonplace. When a student tells a joke to one of his peers and they all laugh at this joke, this student is more likely to continue this behavior of telling jokes because his joke was reinforced by the sound of their laughing. However, if a peer tells the student his joke is "silly" or "stupid", he will be punished by telling the joke and his likelihood of telling another joke is decreased.

Self-punishment of responses would include the arranging of punishment contingent upon undesired responses. This might be seen in the behavior of whipping oneself which some monks and religious persons do. This is different from aversive stimulation in that, for example, the alarm clock generates escape from the alarm, while self-punishment presents stimulation after the fact to reduce the probability of future behavior.^[38]: 237

Punishment is more like conformity than self-control because with self-control there needs to be an internal drive, not an external source of punishment, that makes the person want to do something. With a learning system of punishment the person does not make their decision based upon what they want, rather they base it on the additional external factors. When you use a negative reinforcement you are more likely to influence their internal decisions and allow them to make the choice on their own whereas with a punishment the person will make their decisions based upon the consequences rather than exerting self-control. The best way to learn self-control is with "free will" in which people perceive they are making their own choices.^[30]

Skinner noted that various philosophies and religions exemplified this principle by instructing believers to (for example) love their enemies.^[49] When we are filled with rage or hatred we might control ourselves by "doing something else" or, more specifically, something that is incompatible with our desired but inappropriate response.

Functional imaging of the brain has shown that self-control correlates with activity in an area in the dorsolateral prefrontal cortex (dlPFC), a part of the frontal lobe. This area is distinct from those involved in generating intentional actions, attending to intentions, or selecting between alternatives.^[50] Self-control occurs through top-down inhibition of the premotor cortex,^[51] which essentially means using perception and mental effort to reign in behavior and action as opposed to allowing emotions or sensory experience (bottom-up) to control and drive behavior. There is some debate about the mechanism of self-control and how it emerges. Researchers believed the bottom-up approach, relying on sensory experience and immediate stimuli, guided self-control behavior. The more time a person spends thinking about a rewarding stimulus, the more likely he or she will experience a desire for it. Information that is most important gains control of working memory, and can then be processed through a top-down mechanism.^[52] Evidence suggests that top-down processing plays a strong role in self-control. Top-down processing can regulate bottom-up attentional mechanisms. To demonstrate this, researchers studied working memory and distraction by presenting participants with neutral or negative pictures and then a math problem or no task. They found that participants reported less negative moods after solving the math problem compared to the no task group, which they attributed to an influence on working memory capacity.^[15][53]

Many researchers work on identifying the brain areas involved in the exertion of self-control. Many different areas are known to be involved. In relation to self-control mechanisms, the reward centers in the brain compare external stimuli versus internal need states and a person's learning history.^[15][54] At the biological level, a loss of control is thought to be caused by a malfunctioning of a decision mechanism.

Much of the work on how the brain makes decisions is based on evidence from perceptual learning combined with neuroimaging where it has been found that the pre-frontal cortex has a major impact on how people make choices.^[55]

Subjects are often tested on tasks that are not typically associated with self-control, but are more general decision tasks.^{[citation needed]} Nevertheless, the research on self-control is informed by such research. Sources for evidence on the neural mechanisms of self-control include fMRI studies on human subjects, neural recordings on animals, lesion studies on humans and animals, and clinical behavioral studies on humans with self-control disorders.^{[citation needed]}

There is broad agreement that the cortex is involved in self-control, specifically the pre-frontal cortex.^[55] A mechanistic account of self-control could have tremendous explanatory value and clinical application. What follows is a survey of some important literature on the brain regions involved in self-control.

The prefrontal cortex is located in the most anterior portion of the frontal lobe in the brain. It forms a larger portion of the cortex in humans, taking up about a third of the cortex, and being far more complex than in other animals.^[56] The dendrites in the prefrontal cortex contain up to 16 times as many dendritic spines as neurons in other cortical areas. Due to this, the prefrontal cortex integrates a large amount of information.^[57]: 104 The orbitofrontal cortex cells are important in self-control. If an individual has the choice between an immediate reward or a more valuable reward they can receive later, they would most likely try to control the impulse of taking the inferior immediate reward. If that individual has a damaged orbitofrontal cortex, this impulse control will most likely not be as strong; they may be more likely to take the immediate reinforcement. Lack of impulse control in children may be attributable to the fact that the prefrontal cortex develops slowly.^[57]: 406

Todd A. Hare et al. use functional MRI techniques to show that the ventromedial prefrontal cortex (vmPFC) and the dorsolateral prefrontal cortex (DLPFC) are crucial to the exertion of self-control. They found the vmPFC encoded the value placed on pleasurable, but ultimately self defeating behavior versus that placed on long-term goals. Another discovery was the fact that the exertion of self-control required the modulation of the vmPFC by the DLPFC. The study found that a lack of self-control was strongly correlated with reduced activity in the DLPFC. Hare's study is especially relevant to the self-control literature because it suggests that an important cause of poor self-control is a defective DLPFC.^[58]

Alexandra W. Logue studies how outcomes change the possibilities of a self-control choice being made. Logue identifies three possible outcome effects: outcome delays, outcome size, and outcome contingencies.^[30]

outcome delays

A delay in a positive outcome results in the perception that the outcome is less valuable than an outcome which is more readily achieved. The devaluing of the delayed outcome can cause less self-control. A way to increase self-control in situations of a delayed outcome is to pre-expose the outcome. Pre-exposure reduces the frustrations related to the delay of the outcome. An example of this is signing bonuses.

outcome size

There tends to be a relationship between the value of the incentive and the desired outcome: the larger the desired outcome, the larger the value. Some factors that decrease value include delay, effort/cost, and uncertainty. A decision tends to be based on the option with the highest value at the time of the decision.

outcome contingencies

The relationship between responses and outcomes, or "outcome contingencies", impact the degree of self-control that a person exercises. For instance, if a person is able to change his choice after the initial choice is made, the person is far more likely to take the impulsive, rather than self-controlled, choice. Additionally, it is possible for people to make a precommitment action—one meant to lead to a self-controlled action at a later period in time. When a person sets an alarm clock, for example, they are making a precommitted response to wake up early in the morning. Hence, that person is more likely to exercise the self-controlled decision to wake up, rather than to fall back in bed for a little more sleep.

Cassandra B. Whyte studied locus of control which is the degree to which people think that they, as opposed to external sources, have control over their outcomes. Results indicated that academic performance was higher among people who think their decisions meaningfully impact their outcomes. These outcomes may be due to the belief that they have options from which to choose from, which facilitates more hopeful decision-making behavior when compared to dependence on externally determined outcomes that require less commitment, effort, or self-control.^[59]

Many things affect one's ability to exert self-control; one of these is glucose levels in the brain. Exerting self-control depletes glucose. Reduced glucose, and poor glucose tolerance (reduced ability to transport glucose to the brain) are correlated with lower performance in tests of self-control, particularly in difficult new situations.^[60] Self-control demands that an individual work to overcome thoughts, emotions, and automatic responses/impulses. These efforts require higher blood glucose levels. Lower blood glucose levels can lead to unsuccessful self-control abilities.^[61] Alcohol causes a decrease of glucose levels in both the brain and the body,^{[citation needed]} and it also has an impairing effect on many forms of self-control. Furthermore, failure of self-control is most likely to occur during times of the day when glucose is used least effectively. Self-control thus appears highly susceptible to glucose.^[60]

An alternative explanation of the limited amounts^[specify] of glucose that are found^[specify] is that this depends on the allocation of glucose, not on limited supply of glucose. According to this theory, the brain has sufficient resources of glucose and also has the possibility of delivering the glucose, but the personal priorities and motivations of the individual cause the glucose to be allocated to other sites. As of 2012 this theory has not been tested.^[62]

In the 1960s, Walter Mischel tested four-year-old children for self-control via the "marshmallow test": the children were each given a marshmallow and told that they can eat it anytime they want, but if they waited 15 minutes, they would receive another marshmallow. Follow-up studies showed that the results correlated well with these children's success levels in later life in the form of greater academic achievement.^[63]

A strategy used in the marshmallow test was to focus on "hot" or "cool" features of an object. The children were encouraged to think about the marshmallow's "cool features" such as its shape and texture, possibly comparing it to a cotton ball or a cloud. The "hot features" of the marshmallow would be its sweet, sticky tastiness. These hot features make it more difficult to delay gratification. By focusing on the cool features, the mind is adverted from the appealing aspects of the marshmallow, and self-control is more plausible.^[64]

Years later Mischel reached out to the participants of his study, who were then in their 40s. He found that those who showed less self-control by taking the single marshmallow in the initial study were more likely to develop problems with relationships, stress, and drug abuse later in life. Mischel carried out the experiment again with the same participants in order to see which parts of the brain were active during the process of self-control. The participants received MRI scans to show brain activity. The results showed that those who exhibited lower levels of self-control had higher brain activity in the ventral striatum, the area that deals with positive rewards.^[65]

Self-control is negatively correlated with sociotropy^[66] which in turn is correlated with depression.^[67]

Ego depletion is the theory that self-control requires energy and focus, and over an extended period of self-control demands, this energy and focus can fatigue. There are ways to help this ego depletion. One way is through rest and relaxation from these high demands. Additionally, training self-control with certain behaviors such as practicing self awareness^[68] may also help to strengthen an individual's self-control, as may motivational incentives and supplementation of glucose.^[69] Training on self-control tasks such as improving posture and monitoring eating habits might help boost one's ability to resist giving in to impulses. This may be particularly effective in those who would otherwise have difficulty controlling their impulses.^[70]

However, there is conflicting evidence about whether ego depletion is a real effect; meta-analyses have mostly found no evidence that the effect exists. For more details, see the main ego depletion page.

• Discipline in our life (religious tract)
• Teaching Children the Art of Self-Control