The StrengthModel of Self-Control

CU R RE N T D I R E CT I O NS I N P SYC H OL OG I C AL SC I EN C E
The Strength Model of
Self-Control
Roy F. Baumeister,1 Kathleen D. Vohs,2 and Dianne M. Tice1
1Florida State University and 2University of Minnesota
ABSTRACT—Self-control is a central function of the self
Self-control enables a person to restrain or override one re-
and an important key to success in life. The exertion of
sponse, thereby making a different response possible.
self-control appears to depend on a limited resource. Just
Self-control has attracted increasing attention from psychol-
as a muscle gets tired from exertion, acts of self-control
ogists for two main reasons. At the theoretical level, self-control
cause short-term impairments (ego depletion) in subsequent
holds important keys to understanding the nature and functions
self-control, even on unrelated tasks. Research has
of the self. Meanwhile, the practical applications of self-control
supported the strength model in the domains of eating,
have attracted study in many contexts. Inadequate self-control
drinking, spending, sexuality, intelligent thought, making
has been linked to behavioral and impulse-control problems,
choices, and interpersonal behavior. Motivational or
including overeating, alcohol and drug abuse, crime and
framing factors can temporarily block the deleterious effects
violence, overspending, sexually impulsive behavior, unwanted
of being in a state of ego depletion. Blood glucose is an
pregnancy, and smoking (e.g., Baumeister, Heatherton, & Tice,
important component of the energy.
1994; Gottfredson & Hirschi, 1990; Tangney, Baumeister,
& Boone, 2004; Vohs & Faber, 2007). It may also be linked
KEYWORDS—self-control; ego depletion; willpower; impulse;
to emotional problems, school underachievement, lack of
strength
persistence, various failures at task performance, relationship
problems and dissolution, and more.
Every day, people resist impulses to go back to sleep, to eat
fattening or forbidden foods, to say or do hurtful things to their
LIMITED RESOURCES
relationship partners, to play instead of work, to engage in in-
appropriate sexual or violent acts, and to do countless other sorts
Folk discussions of self-control have long invoked the idea of
of problematic behaviors—that is, ones that might feel good
willpower, which implies a kind of strength or energy. During the
immediately or be easy but that carry long-term costs or violate
heyday of the behaviorist and cognitive revolutions, however,
the rules and guidelines of proper behavior. What enables the
psychology had little use for theorizing in energy terms, and
human animal to follow rules and norms prescribed by society
self theories in particular had scarcely mentioned energy
and to resist doing what it selfishly wants?
since Freud. However, in the 1990s, research findings began to
Self-control refers to the capacity for altering one’s own re-
point toward an energy model of self-control. There might be
sponses, especially to bring them into line with standards such
something to the willpower notion after all.
as ideals, values, morals, and social expectations, and to support
The idea that self-control depended on a limited energy
the pursuit of long-term goals. Many writers use the terms self-
resource was suggested by us (Baumeister et al., 1994) based on
control and self-regulation interchangeably, but those who make
our review of multiple research literatures. We observed that
a distinction typically consider self-control to be the deliberate,
self-control appeared vulnerable to deterioration over time from
conscious, effortful subset of self-regulation. In contrast,
repeated exertions, resembling a muscle that gets tired. The
homeostatic processes such as maintaining a constant body
implication was that effortful self-regulation depends on a limited
temperature may be called self-regulation but not self-control.
resource that becomes depleted by any acts of self-control,
causing subsequent performance even on other self-control
tasks to become worse.
The basic approach to testing the depleted-resource hypothesis
Address correspondence to Roy F. Baumeister, Florida State Uni-
was to have some research participants perform a first self-control
versity, Department of Psychology, 1107 W. Call Street, Tallahassee,
FL 32306-4301; e-mail: baumeister@psy.fsu.edu.
task, while others performed a comparable but neutral task, and
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Copyright r 2007 Association for Psychological Science
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The Strength Model of Self-Control
then all would move on to perform a second, unrelated self-
are these patterns due to participants refusing to exert themselves
control task. If self-control consumes a limited resource, then
on the second task because they think they have done enough on
performing the first task should deplete the person’s resource,
the first task, as various findings have shown (see Baumeister,
leaving less available for the second task—and therefore
Gailliot, DeWall, & Oaten, 2006); for example, it has been found
causing poorer performance on the second task. Other theories
that depleted participants will subject themselves to more
would make different predictions. For example, if self-control
boredom than will nondepleted ones on a second task.
mainly involved activating a cognitive schema or mental
Is willpower more than a metaphor? Gailliot et al. (2007)
program, then the first self-control task should prime the schema
explored the role of glucose, a chemical in the bloodstream that
and activate the self-control system, so performance on the
can be converted to neurotransmitters and thus furnishes fuel
second self-control task should improve, not worsen.
for brain activity. Acts of self-control cause reductions in blood-
Early laboratory evidence for depleted resources in self-
glucose levels, which in turn predict poor self-control on
regulation was reported by Muraven, Tice, and Baumeister
behavioral tasks. Drinking a glass of lemonade with sugar helped
(1998) and Baumeister, Bratslavsky, Muraven, and Tice (1998).
counteract these effects, presumably by restoring glucose in
In one study, watching an emotionally evocative film while trying
the blood. Lemonade mixed with diet sweeteners (no glucose)
either to amplify or to stifle one’s emotional response caused
had no such empowering effect.
poorer performance on a subsequent test of physical (handgrip)
stamina, as compared to watching the film without trying to
ELABORATING THE STRENGTH MODEL
control one’s emotions. (Stamina counts as a measure of
self-control because it involves resisting fatigue and overriding
The analogy between self-control and a muscle was suggested
the urge to quit.) In another study, suppressing a forbidden
by the early findings that self-control performance deteriorates
thought weakened people’s ability to stifle laughter afterward.
after initial exertions, just as a muscle gets tired from exertion.
In another, resisting the temptation to eat chocolates and
Other revealing aspects of self-control performance also extend
cookies (and making oneself eat health-promoting but un-
the resemblance to a muscle (see Box 1).
appetizing radishes instead) caused participants to give up faster
First, just as exercise can make muscles stronger, there are
on a subsequent frustrating task, as compared to people who
signs that regular exertions of self-control can improve willpower
had not exerted self-control (see Fig. 1). These studies all
strength (for a review, see Baumeister et al., 2006). These
pointed toward the conclusion that the first self-control task
improvements typically take the form of resistance to depletion,
consumed and depleted some kind of psychological resource
in the sense that performance at self-control tasks deteriorates at
that was therefore less available to help performance on the
a slower rate. Targeted efforts to control behavior in one area,
second self-control task.
such as spending money or exercise, lead to improvements
The term ego depletion was coined to refer to the state of
in unrelated areas, such as studying or household chores.
diminished resources following exertion of self-control (or other
And daily exercises in self-control, such as improving posture,
tasks that might deplete the same resource). These ego-depletion
altering verbal behavior, and using one’s nondominant hand
effects are not due to a diminished a sense of self-efficacy or to the
for simple tasks, gradually produce improvements in
inference that one is poor at self-control. Wallace and Baumeister
self-control as measured by laboratory tasks. The finding
(2002) explicitly manipulated feedback about success and failure
that these improvements carry over into tasks vastly different
at self-control and measured self-efficacy, but neither factor had
from the daily exercises shows that the improvements are
any discernible impact on the ego-depletion patterns. Nor
not due to simply increasing skill or acquiring self-efficacy
from practice.
Second, just as athletes begin to conserve their remaining
25
strength when their muscles begin to tire, so do self-controllers
20
when some of their self-regulatory resources have been
(min)
expended. The severity of behavioral impairment during
nce 15
depletion depends in part on whether the person expects further
siste
challenges and demands. When people expect to have to exert
per 10
of
self-control later, they will curtail current performance more
5
severely than if no such demands are anticipated (Muraven,
Duration
Shmueli, & Burkley, 2006).
0
Third, and consistent with the conservation hypothesis,
Eat radish
Eat chocolate
No-food control
people can exert self-control despite ego depletion if the stakes
Fig. 1. Speed of giving up on an unsolvable task after eating chocolate or
are high enough. Offering cash incentives or other motives for
exerting self-control to resist chocolate in favor of radishes on a previous
good performance counteracts the effects of ego depletion
task (as compared to a no-food control). From Baumeister, Bratslavsky,
Muraven, & Tice, 1998.
(Muraven & Slessareva, 2003). This may seem surprising but in
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Roy F. Baumeister, Kathleen D. Vohs, and Dianne M. Tice
BOX 1.
How far the muscle analogy can be pushed remains an open
Contexts, Moderators, Mediators, and Implications of the
question. Are there self-control states resembling sprained or
Limited-Resource Effect
injured muscles? One might speculate that burnout or
other pathological states resemble the incapacities stemming
Responses that require self-regulation include
from muscles that have been abused beyond their normal
 Controlling thoughts
capacity for recovery.
 Managing emotions
Multiple lines of work have identified procedures that can
 Overcoming unwanted impulses (e.g., not eating tempting candies
because of being on a diet)
moderate or counteract the effects of ego depletion. Inducing
 Fixing attention
a state of positive emotion such as humor seems to have that
 Guiding behavior
effect (Tice, Baumeister, Shmueli, & Muraven, 2007). Having
 Making many choices
implementation intentions—formulating ‘‘if–then’’ statements
Behaviors that are sensitive to depletion of self-regulatory resources include
about how to behave in a situation prior to entering it—seems
 Eating among dieters
to be effective most likely because such intentions operate
 Overspending
as behavioral plans and guidelines that reduce the need for
 Aggression after being provoked
 Sexual impulses
executive control (Webb & Sheeran, 2003). To be sure, none of
 Intelligent and logical decision making
these procedures clearly counteracts the depleted state in the
Interpersonal processes that require self-regulatory resources include
sense of replenishing the depleted resource. Rather, they may all
 Self-presentation or impression management
operate by inducing the person to expend more of the depleted
 Kindness in response to a partner’s bad behavior
resource. In contrast, there is some reason to think that
 Dealing with demanding, difficult partners
replenishing glucose in the bloodstream does actually rectify the
 Interracial interactions
Moderators of ego depletion include
depletion by restoring the depleted resource (Gailliot et al., 2007).
 Heightened motivation to achieve a goal
 Collectivistic cultural background
PRACTICAL APPLICATIONS
Physical indicators of ego depletion include
 Heart-rate variability
Understanding self-control has potential applications across
 Neural changes using electroencephalograph methods
Mediators of ego depletion include
a broad spectrum of human behavior. At the positive end, self-
control is associated with good adjustment, secure attachment,
 Subjective time perception (time perception is elongated—i.e., time
moves slowly)
and other favorable psychological states (Tangney et al., 2004).
 Blood-glucose levels
At the negative end, poor self-control is associated with elevated
Harmful effects of depletion may be counteracted through
rates of psychopathological complaints and symptoms, as well as
 Humor and laughter
increased vulnerability to various substance-abuse and eating
 Other positive emotions
disorders (Tangney et al., 2004). Evidence that ego depletion
 Cash incentives
contributes to a variety of problem behaviors—including
 Implementation intentions (‘‘if ... then’’ plans)
excessive alcohol consumption, overeating, sexual misbehavior,
 Social goals (e.g., wanting to help people; wanting to be a good
relationship partner)
prejudicial discrimination, and violence—is accumulating.
Intelligent behavior is vital to human success, and it depends
partly on self-control. Some processes, such as rote memory, are
fact it may be highly adaptive. Given the value and importance
fairly automatic and independent of executive control, and these
of the capacity for self-control, it would be dangerous for a
appear to be relatively unaffected by depletion. But logical
person to lose that capacity completely, and so ego depletion
reasoning, extrapolation, and other controlled processes
effects may occur because people start conserving their
depend on control by the self, and performance on these tasks
remaining strength. When people do exert themselves on the
dips sharply when people are depleted (Schmeichel, Vohs, &
second task, they deplete the resource even more, as reflected in
Baumeister, 2003).
severe impairments on a third task that they have not anticipated
Interpersonal processes also seem to hinge on self-regulatory
(Muraven et al., 2006).
operations, with some needing self-control more than others.
To be sure, we think there are levels of depletion beyond
Richeson and Shelton (2003) reasoned that self-control is needed
which people may be unable to control themselves effectively,
for discussing delicate, sensitive issues—for instance talking
regardless of what is at stake. Pragmatic and ethical limitations
about racial politics with a member of a different race—because
have prevented us from showing this in laboratory work thus far.
one has to avoid saying anything that might give offense or be
Again, the muscle analogy is relevant: Mildly tired athletes can
misinterpreted. The researchers had White participants engage
indeed manage to summon the strength for a major exertion at
in such a conversation with a Black person; afterwards, the
decisive moments, but after a certain point fatigue becomes
participants showed impaired performance on the Stroop task,
insurmountable.
a classic measure of self-control in which participants are
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The Strength Model of Self-Control
instructed to say the color in which other color words are printed
regimens work better than others. Finding a reliable way to
(e.g., when seeing the word green printed in blue, the participant
improve self-control would not only shed light on how the self
must override the automatic response of saying ‘‘green’’ in
functions but would also have practical value for therapists,
order to say ‘‘blue’’). Having such a conversation with a member
coaches, educators, parents, and many others.
of one’s own race does not deplete the self and impair sub-
Identifying the biological substrates of self-control depletion
sequent self-control.
(and replenishment) would be another helpful direction for
Presenting a desired image to others can also tax self-control
further work. Better understanding of the developmental process
strength resources (Vohs, Baumeister, & Ciarocco, 2005). After
would likewise strengthen the theory and make it more
exerting effort at managing the impression they made (e.g., when
applicable to human welfare and problems.
trying to convey a particular image while making a recording),
people showed deficits at self-control. Moreover, and conversely,
CONCLUDING REMARKS
after people had exerted self-control, they were less effective at
managing their behavior so as to make a good impression and in
Psychology can contribute to society by finding ways to enable
fact sometimes behaved in annoying or off-putting ways.
people to live healthier, more successful, and more satisfying
lives. Self-control is a promising avenue to achieve this. It
IMPLICATIONS FOR THEORY
appears to facilitate success in life in many spheres, and,
crucially, it appears amenable to improvement. Indeed,
The existence of a single energy resource that is used for a broad
self-control can be grouped with intelligence among the (rather
range of self-control acts suggests that self theory must move
few) traits that are known to contribute to success in human
beyond merely cognitive models. The self is more than a network
life across a broad variety of spheres; yet unlike intelligence,
of cognitive schemas: It is a dynamic system able to manage
self-control appears amenable to improvement from psycho-
behavior in advanced, complex, and biologically expensive
logical interventions, even in adulthood. The strength model can
ways.
illuminate how self-control operates and functions. By building
The use of the body’s energy for complex action control
on this knowledge, psychology may be able to improve the
extends beyond self-control. Recent studies indicate that the
mental health and well-being of many people.
same energy is used for effortful decision making, as well as for
active rather than passive responses (e.g., Vohs et al., 2007).
These seem to correspond to what laypersons understand as
Recommended Reading
‘‘free will,’’ namely the ability to override impulses, behave
Baumeister, R.F., Schmeichel, B.J., & Vohs, K.D. (2007). Self-regulation
morally, show initiative, and behave according to rational
and the executive function: The self as controlling agent. In A.
choices (Baumeister, in press).
Kruglanski & E.T. Higgins (Eds.), Social psychology: Handbook
of basic principles (2nd ed., pp. 516–539). New York: Guilford. A
Most broadly, the strength model of self-control offers
recent and thorough overview of the research in a broad context.
suggestions about how and why the human self evolved in its
Gailliot, M.T., Baumeister, R.F., DeWall, C.N., Maner, J.K., Plant, E.A.,
current form. The functional purposes of the self almost certainly
& Tice, D.M. et al. (2007). (See References). Reports experiments
include managing behavior toward fostering enlightened
linking behavioral self-control measures to blood glucose.
self-interest and facilitating group membership by garnering
Baumeister, R.F., Gailliot, M., DeWall, C.N., & Oaten, M. (2006). (See
social acceptance. Self-control is helpful for both these goals.
References). An overview of the research program on self-control with
emphasis on personality implications and alternative explanations.
The role of energy suggests that self-control is a complex,
biologically expensive form of behavior. Thus, we may infer that,
to enable humans to create and sustain the complicated groups
to which they belong, including cultural systems, evolution had
Acknowledgments—The authors gratefully acknowledge re-
to find a way to use the body’s energy to control behavior in
search support from the Templeton Foundation.
these advanced and subtle ways. For example, human beings
everywhere regulate their behavior according to various rules,
REFERENCES
such as social norms, moral principles, and laws.
Baumeister, R.F. (in press). Free will in scientific psychology.
FURTHER DIRECTIONS
Perspectives on Psychological Science.
Baumeister, R.F., Bratslavsky, E., Muraven, M., & Tice, D.M. (1998).
A particularly broad and important question is what other forms
Ego depletion: Is the active self a limited resource? Journal of
Personality and Social Psychology, 74, 1252–1265.
of behavior (beyond self-control and choice) use this limited
Baumeister, R.F., Gailliot, M., DeWall, C.N., & Oaten, M. (2006). Self-
resource: How special is this form of mental effort? We noted that
regulation and personality: How interventions increase regulatory
success at building self-control through exercises has been
success, and how depletion moderates the effects of traits on
inconsistent, so it is also necessary to explore why some
behavior. Journal of Personality, 74, 1773–1801.
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Roy F. Baumeister, Kathleen D. Vohs, and Dianne M. Tice
Baumeister, R.F., Heatherton, T.F., & Tice, D.M. (1994). Losing control:
Tangney, J.P., Baumeister, R.F., & Boone, A.L. (2004). High self-control
How and why people fail at self-regulation. San Diego, CA:
predicts good adjustment, less pathology, better grades, and
Academic Press.
interpersonal success. Journal of Personality, 72, 271–322.
Gailliot, M.T., Baumeister, R.F., DeWall, C.N., Maner, J.K., Plant, E.A.,
Tice, D.M., Baumeister, R.F., Shmueli, D., & Muraven, M. (2007).
& Tice, D.M., et al. (2007). Self-control relies on glucose as a
Restoring the self: Positive affect helps improve self-regulation
limited energy source: Willpower is more than a metaphor. Journal
following ego depletion. Journal of Experimental Social Psychol-
of Personality and Social Psychology, 92, 325–336.
ogy, 43, 379–384.
Gottfredson, M.R., & Hirschi, T. (1990). A general theory of crime.
Vohs, K.D., Baumeister, R.F., & Ciarocco, N. (2005). Self-regulation
Stanford, CA: Stanford University Press.
and self-presentation: Regulatory resource depletion impairs
Muraven, M., Shmueli, D., & Burkley, E. (2006). Conserving self-control
impression management and effortful self-presentation depletes
strength. Journal of Personality and Social Psychology, 91,
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524–537.
ogy, 88, 632–657.
Muraven, M., & Slessareva, E. (2003). Mechanisms of self-control failure:
Vohs, K.D., Baumeister, R.F., Twenge, J.M., Nelson, N.M., Rawn, C.D.,
Motivation and limited resources. Personality and Social
Schmeichel, B.J., & Tice, D.M. (2007) Making choices impairs sub-
Psychology Bulletin, 29, 894–906.
sequent self-control: A limited resource account of decision making, self-
Muraven, M., Tice, D.M., & Baumeister, R.F. (1998). Self-control
regulation, and active initiative. Manuscript submitted for publication.
as limited resource: Regulatory depletion patterns. Journal of
Vohs, K.D., & Faber, R.J. (2007). Spent resources: Self-regulatory
Personality and Social Psychology, 74, 774–789.
resource availability affects impulse buying. Journal of Consumer
Richeson, J.A., & Shelton, J.N. (2003). When prejudice does not pay:
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Effects of interracial contact on executive function. Psychological
Wallace, H.M., & Baumeister, R.F. (2002). The effects of success
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