Beliefs About Willpower Moderate The Effect of Previous Day Demands on Next Day’s Expectations and Effective Goal Striving

Abstract

Research suggests that beliefs about willpower affect self-regulation following previous self-regulatory demands (Job et al., 2010). Some people believe that their willpower is limited, meaning that after a demanding task it needs to be replenished (limited theory). By contrast, others believe that willpower is not limited and that previous self-control tasks even activate willpower (non-limited theory). We hypothesized that when people experience a demanding day their beliefs about willpower predict their expected capacity to self-regulate and their actual self-regulation on the following day. In a daily diary study (N = 157), we measured students' daily level of demands, their expected performance in unpleasant tasks, and their effective goal striving. Results showed that following a demanding day, students with a non-limited theory had higher expectations about their progress in unpleasant tasks and were striving more efficiently for their goals than students with a limited theory. These findings suggest that beliefs about willpower affect whether demands experienced on a previous day have positive or negative consequences on people's self-regulation.

Full text

ORIGINAL RESEARCH
published: 14 October 2015
doi: 10.3389/fpsyg.2015.01496
Edited by:
Marcel Zentner,
University of Innsbruck, Austria
Reviewed by:
Martin S. Hagger,
Curtin University, Australia
Benjamin P. Chapman,
University of Rochester Medical
Center, USA
*Correspondence:
Veronika Job,
Developmental Psychology:
Adulthood, Department
of Psychology, University of Zurich,
Binzmuehlestrasse 14/11,
8050 Zurich, Switzerland
v.job@psychologie.uzh.ch
Specialty section:
This article was submitted to
Personality and Social Psychology,
a section of the journal
Frontiers in Psychology
Received: 02 June 2015
Accepted: 16 September 2015
Published: 14 October 2015
Citation:
Bernecker K and Job V (2015) Beliefs
about willpower moderate the effect
of previous day demands on next
day’s expectations and effective goal
striving. Front. Psychol. 6:1496.
doi: 10.3389/fpsyg.2015.01496
Beliefs about willpower moderate the
effect of previous day demands on
next day’s expectations and effective
goal striving
Katharina Bernecker1and Veronika Job2*
1Psychology of Motivation, Volition, and Emotion, Department of Psychology, University of Zurich, Zurich, Switzerland,
2Developmental Psychology: Adulthood, Department of Psychology, University of Zurich, Zurich, Switzerland
Research suggests that beliefs about willpower affect self-regulation following previous
self-regulatory demands (Job et al., 2010). Some people believe that their willpower
is limited, meaning that after a demanding task it needs to be replenished (limited
theory). By contrast, others believe that willpower is not limited and that previous self-
control tasks even activate willpower (non-limited theory). We hypothesized that when
people experience a demanding day their beliefs about willpower predict their expected
capacity to self-regulate and their actual self-regulation on the following day. In a daily
diary study (N=157), we measured students’ daily level of demands, their expected
performance in unpleasant tasks, and their effective goal striving. Results showed that
following a demanding day, students with a non-limited theory had higher expectations
about their progress in unpleasant tasks and were striving more efficiently for their
goals than students with a limited theory. These findings suggest that beliefs about
willpower affect whether demands experienced on a previous day have positive or
negative consequences on people’s self-regulation.
Keywords: implicit theories about willpower, goal striving, self-control, optimism, self-efficacy
Introduction
Over a century ago, William James (1907) argued that people’s levels of physical and mental energy
are not always the same but change from day to day. He argued that “Every one is familiar with
the phenomenon of feeling more or less alive on different days. Every one knows on any given
day that there are energies slumbering in him which the incitements of that day do not call forth,
but which he might display if these were greater” (p. 322). In recent years, the idea of temporal
changes in energy levels was applied to an important mental capacity, namely self-control. Self-
control is the ability to alter thoughts, emotions, and behaviors in a way that helps individuals to
achieve their long-term goals (Baumeister et al., 1998, 2007). The influential strength model of
self-control argues that self-control fluctuates because it is based on a limited resource, which gets
easily depleted when self-control is exerted (Baumeister and Heatherton, 1996;Baumeister, 2002;
Oaten and Cheng, 2005). As support for the model numerous experimental studies found that
self-control performance is impaired by previous acts of self-control (Hagger et al., 2010). Thus,
according to the strength model, self-control capacity fluctuates due to the depletion of a limited
resource.
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Bernecker and Job Willpower theories and previous day demands
James (1907) had a different idea about what might
cause fluctuations in daily levels of energy. In contrast to
the strength model of self-control, he argued that people
generally possess an indefinite amount of mental and physical
resources; what changes is how much they tap into these
resources on a given day. He further believed that most people
habitually fail to use the plenty reservoirs of energy they
possess (James, 1907). Recent empirical findings support this
notion and suggest that people’s beliefs about willpower affect
self-control performance following initial self-control exertion
(Job et al., 2010). People with a limited theory believe that
exerting self-control, for instance, by working on a strenuous
mental task or resisting a temptation, depletes their willpower
resource. In order to be available again the resource needs
to be restored, for instance, by taking a break or eating.
In contrast, people with a non-limited theory believe that
exerting self-control can even activate their willpower (Job
et al., 2010). Several laboratory experiments showed that people
who endorse a limited theory show self-control impairments
after initial self-control exertion, while people with a non-
limited theory perform well regardless of previous self-control
demands (Job et al., 2010;Miller et al., 2012). Importantly,
the same pattern of results emerged when willpower theories
were not measured but manipulated (Job et al., 2010;Miller
et al., 2012). These results suggest that willpower beliefs play
a causal role and determine whether people are able to recruit
the required willpower to succeed in consecutive self-control
tasks.
Despite these apparently functional effects of a non-limited
theory, a recent study suggests that a non-limited theory may
backfire when people face sustained self-regulatory demands
(Vohs et al., 2013). Whereas participants with an induced
non-limited theory outperformed participants with an induced
limited theory when self-regulatory performance was measured
after mild depletion (two self-control tasks), the pattern reversed
after severe depletion (four self-control tasks) (Vohs et al.,
2013). Based on these findings it was speculated that a non-
limited theory may persuade people to overexert their resources,
resulting in self-control failure in the face of high demands.
In spite of these considerations, field studies examining self-
control performance in real life show that people with a non-
limited theory are even better able to exert self-control in
phases of high self-regulatory demands than people with a
limited theory (Job et al., 2010, 2015b). In one study, students
were surveyed once at the beginning, once in the middle,
and once at the end of the term during final exams (Job
et al., 2010, Study 4). Results showed that in the final exam
period students with a limited theory reported more self-
regulatory failure than students with a non-limited theory.
They procrastinated more, ate less healthy, and reported worse
self-regulation with regard to a challenging personal goal.
In the middle of the term, when students faced low self-
regulatory demands, self-control failure was overall less likely
independent of students’ willpower theories (Job et al., 2010,
Study 4). In a second study, students were surveyed weekly
in the five weeks before their exams (Job et al., 2015b). As
an improvement of the previous study, self-regulatory demands
(e.g., assignments, interpersonal conflicts, health problems) were
assessed alongside with different indicators of self-regulation.
Inconsistent with Vohs et al.’s (2013) findings, students with
a limited theory reported worse self-regulation when they
faced high demands as compared to the average student. In
contrast, students with a non-limited theory even showed the
opposite trend and reported a healthier diet when facing high
demands. This study further assessed students’ grade point
average and found that a limited theory predicted lower grades
(controlling for previous grades), especially among students
with a high course load. Students with a non-limited theory
even performed slightly better when they had a heavy course
load. For them increased self-regulatory demands had a positive
effect on their performance (Job et al., 2015b). In sum, the
findings suggest that willpower theories predict self-control
performance when demands accumulate and that people with
a non-limited theory might even benefit from increased self-
regulatory demands.
However, one limitation of both studies is that effects of
demands were observed only on the between-subjects level. That
is, the effects of willpower theories were compared for individuals
with high versus low demands (i.e., comparing individuals’
weekly demands to the average demand of all students in that
week, Job et al., 2015b). But willpower theories might also
interact with demands on a within-subject level in predicting
self-control performance (i.e., comparing weekly demands to
individuals’ own average in demands). In one study, within-
person effects of demands were examined but turned out to
be not significant (Job et al., 2015b). This was probably due to
the long time periods between measurement points (i.e., one
week), causing the variance in demands to be greater between
participants than within participants. Yet, examining within-
subject processes is important, because research shows that
they do not necessarily converge with between-person processes
(Hoffman and Stawski, 2009). Further, between-subjects effects
can be caused by third variables or general person characteristics
that may explain the differences between subgroups of people in
asample.
The present research, therefore, aims to test whether willpower
theories interact with within-person variations in previous
demands to predict effective goal striving as a measure for
successful self-regulation in everyday life. We hypothesized that
people with a limited willpower theory show less effective goal
striving when previous demands exceed their own personal
average. In contrast, people with a non-limited theory should
show effective goal striving even when previous demands exceed
their personal average. This is because individuals with a non-
limited theory should perceive themselves as having sufficient
resources to strive for important personal goals even if they
had to deal with previous self-regulatory demands. People
endorsing a limited theory should be more guided by the
motive to conserve resources once these resources have been
taxed and thus apply less of their resources to current personal
goals.
Adopting James (1907) idea of daily fluctuations in the use
of energy resources we conducted a daily diary study. This
design allowed us to test whether demands experienced on
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Bernecker and Job Willpower theories and previous day demands
any given day affect how effectively people strive for their
goals on the next day. The daily diary method allows people
to closely discriminate between days and therefore naturally
increases the ratio of within- to between-person variance.
Further, the high frequency measurement increases the power
of detecting a probably small carryover effect of previous
day demands to the next day. One reason why we expected
previous day demands to matter is that research showed
that willpower theories moderate the effects of previous self-
regulatory demands (Job et al., 2010). Further, retrospective
reports of demands and effective goals striving reported on
the same day might influence each other. Therefore, testing
effects of the previous day has the methodological advantage
of independent measurement of demands and self-control
performance.
The second goal of the present study is to examine the
role of expectations in the context of willpower theories.
When people view their willpower either as limited or non-
limited this should affect their expectations about their ability
to exert self-control, particularly when their willpower was
previously taxed. Individuals who believe that their resources
are diminished due to a previous self-control act, might
be more motivated to conserve what is left and thus align
their expectations about their future capacity to self-control
accordingly. Conversely, people who perceive themselves as
having sufficient resources should have higher expectations
about their future capacity to self-control. These differences
in expectations might be one plausible mediator of the effect
of willpower theories on self-control performance. However,
so far, no study has investigated the effects of willpower
theories on expectations. In the present study, we explored
whether willpower theories determine individuals’ expectations
particularly after a demanding day. Because change on the
expectations should be specific to tasks that require self-control,
we assessed people’s expectations about their performance in
unpleasant and pleasant tasks. Tasks that are unpleasant and
do not have any hedonic value should require self-control
to perform, because they are at odds with a person’s short-
term motives (Fujita, 2011). In contrast, pleasant tasks should
not require self-control because they satisfy a person’s short-
term motives. Thus, we expected that, after a demanding day
(more than after a non-demanding day), willpower theories
should affect people’s expected performance in unpleasant
tasks but not in pleasant tasks. Further, these differences in
expectation might be part of the mechanism and explain why
willpower theories interact with demands to predict effective goal
striving.
In addition to these task-specific expectations about
performance, we also aimed to examine how willpower
theories relate to more global expectations, such as optimism,
pessimism, and general self-efficacy. Although these constructs
should be related to willpower theories (people with a limited
theory might be less optimistic, more pessimistic, and have lower
general self-efficacy), controlling for these global expectations
should not affect the proposed interactive effects of implicit
theories about willpower and previous day demands on effective
goal striving.
Materials and Methods
This study was carried out in accordance with the ethical
standards of the institutional research committee and with
the 1964 Helsinki declaration and its later amendments for
comparable ethical standards. Informed consent was obtained
from all individual participants included in the study.
Participants and Procedure
Participants were 157 students from a public university in
Switzerland (132 women; Mage =22.96 years, Range: 18–
51 years) who were recruited via lectures, flyers on campus,
mailing lists, and online forums for students.
After signing up for the “Smartphone Study on Well-
being” via email participants received a link to the baseline
survey in the third week of the spring term. The baseline
survey assessed individual difference measures, such as willpower
theories, optimism, pessimism, and general self-efficacy. Within
the following 9 weeks, participants completed two diary phases
of five consecutive days each (Monday to Friday). To ensure
sufficient variance in daily demands we placed the first diary
phase in the beginning of the term (6th of 15 weeks) and the
second diary phase close to the exam period at the end of the
term (13th week). On each day participants were emailed a link to
a morning survey at 7:00 am with a request to respond until 11:00
am, and a link to an evening survey at 6:00 pm with the request to
answer until 11:00 pm. Both links expired at the announced time.
Participants received 10 Swiss Francs ($10.70) for completing
the baseline questionnaire, 10 Swiss Francs for completing
each diary period and another 20 Swiss Francs for completing
80% of the daily questionnaires. On average, participants
completed 18.00 (SD =3.29, Range: 3–20) daily questionnaires.
Overall, 1378 out of 1570 (87.8%) morning questionnaires
and 1390 out of 1570 (88.5%) evening questionnaires were
completed.
Individual Difference Measures Assessed at
Baseline
Implicit Theories About Willpower
At baseline, participants completed 12 items assessing implicit
theories about willpower with respect to strenuous mental
activities and resisting temptations (Job et al., 2010). Example
items are “After a strenuous mental activity your energy is
depleted and you must rest to get it refueled again” (limited
theory) and “Your mental stamina fuels itself; even after
strenuous mental exertion you can continue doing more of it”
(non-limited theory), which were answered on a 6-point scale
(1=Strongly agree,6=Strongly disagree, α=0.81). Items
representing a limited theory were reverse-scored so that on the
averaged scale higher values represent greater agreement with a
limited theory.
General Optimism and Pessimism
To examine whether the effects of implicit theories about
willpower were independent of optimism and pessimism, we
administered the German version of the revised Life Orientation
Test (LOT-R; Herzberg et al., 2006;Glaesmer et al., 2008)at
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Bernecker and Job Willpower theories and previous day demands
baseline. Participants indicated on a 5-point scale (1=Strongly
disagree, 5 =Strongly agree) how much they agreed with three
items assessing optimism (e.g., “If something can go wrong for
me, it will,” α=0.68) and three items assessing pessimism (e.g.,
“In uncertain times, I usually expect the best,” α=0.62). Because
optimism and pessimism represent two independent constructs
the items were averaged to two separate scales (Herzberg et al.,
2006).
General Self-efficacy
We assessed general self-efficacy with the German version of the
General Self-efficacy Scale (Schwarzer et al., 1997). Participants
answered 10 items (e.g., “I can always manage to solve difficult
problems if I try hard enough”) on a 4-point scale (1=Not at all
true,4=Exactly true, α=0.77).
Daily Measures of Expectations, Demands,
and Effective Goal Striving
In the morning questionnaire, we assessed expectations about
progress and exhaustion from unpleasant and pleasant tasks.
In the evening questionnaire, we assessed daily demands and
effective goal striving.
Expectations
In the morning, participants were instructed to think about all
unpleasant tasks they were facing that day. One item assessed the
expected amount of unpleasant tasks (“On how many unpleasant
tasks do you have to work today?”; 1=None,5=Agreat
many). Another item assessed their expected progress on these
unpleasant tasks (“What do you think, how much progress will
you make on these tasks?”, 1=None,5=Very much). Another
item assessed their expected exhaustion from these unpleasant
tasks (“What do you think, how exhausting will it be to work
on these tasks?”, 1=Not at all,5=Very much). As control
measure, we let participants answer the same three items about
upcoming pleasant tasks of the day. We did not expect any effect
of willpower theories on expectations about pleasant tasks.
Demands
In the evening, one item assessed demands throughout the day
(i.e., “Overall, how demanding was your day?”, 1 =Notatall,
5=Very much).
Effective Goal Striving
Two items assessed effective goal striving throughout the day
(i.e., “Overall, how efficiently have you worked today?”, 1 =Not
at all,5=Very much; “How often did you work on things
that are important to you? 1 =All the time, 6=At no time,
0.56 <αday <0.71).
Control Variables at Day-level
The order of the days within the diary was coded to control for
linear trends over time (0=1st day,9=10th day). Further, we
controlled in which diary phase the daily survey was completed
(0=1st week,1=2nd week).
Results
Data was analyzed with a hierarchical linear modeling approach
(Bryk and Raudenbush, 1992)usingR(R Core Team,
2013)andthelme4package(Bates et al., 2015). All day-
level variables (Level 1; e.g., demands) were centered at
the person mean (cf. Judge et al., 2006), and person-level
variables (Level 2; e.g., implicit theories about willpower) at the
grand mean. Because day-level variables were centered at the
person mean the results do not refer to differences between
participants but to daily fluctuations within participants. All
models were fitted using a maximum likelihood estimation
procedure.
Preliminary and Descriptive Analyses
For each day-level variable we estimated the ICC1,which
gives the proportion of between-person variance to the total
variance. The values ranged from 0.15 to 0.30, which means
that 15–30% of the variance was between person variance. This
result suggests that data are dependent on the person and,
therefore, justify the use of a multilevel model. However, a
substantial portion of the variance in expectations and effective
goal striving was within-person, which might be predicted
by cross-level interactions between variables measured at day-
level (e.g., demands) and person variables (e.g., willpower
theory).
Tab l e 1 shows the descriptive statistics and zero-order
correlations between the main variables of the study. Willpower
TABLE 1 | Descriptive statistics and zero-order correlations between main variables.
Vari able M(SD) 12345678
(1) Willpower theory 3.34 (0.47)
(2) Demands 2.30 (1.04) 0.10 0.18 0.00 0.15 0.15
(3) Expected amount of UT 2.48 (0.87) 0.17 0.36 −0.15 0.48 0.05
(4) Expected progress in UT 3.65 (0.88) −0.20 −0.07 −0.21 −0.23 0.23
(5) Expected exhaustion from UT 3.37 (0.96) 0.12 0.19 0.48 −0.26 0.09
(6) Effective goal striving 3.05 (1.21) −0.16 0.15 −0.09 0.27 0.04
(7) Optimism 3.68 (0.75) −0.15 −0.01 −0.14 0.04 −0.09 0.20
(8) Pessimism 2.30 (0.73) 0.11 0.13 0.16 0.01 −0.04 0.01 −0.40
(9) Self-efficacy 2.87 (0.38) −0.23 −0.03 −0.25 0.21 −0.14 0.17 0.36 −0.25
Correlations below the diagonal are person-level correlations (N =157) with correlations r >| 0.16| being significant at p <0.05. Correlations above the diagonal are
day-level correlations (N =1390) with correlations r >| 0.05| being significant at p <0.05. UT, unpleasant tasks.
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Bernecker and Job Willpower theories and previous day demands
theories were moderately correlated with people’s mean
reports on demands and expectations on the upcoming day.
People with a limited theory expected a greater amount of
unpleasant tasks, less progress, but more exhaustion resulting
from working on them on the following day. Furthermore,
people with a limited theory, indeed, reported lower effective
goal striving. Last, willpower theories were only moderately
correlated with optimism, pessimism, and self-efficacy,
suggesting that willpower theories differ from these general
expectations. As expected, people with a limited theory were
slightly less optimistic, more pessimistic, and had lower
self-efficacy.
Hypothesis Tests
Do People with a Limited Theory Experience More
Demands at Day-level?
No. We predicted daily demands by implicit theories about
willpower controlling for the effects of day and week. As
expected, demands were perceived to be higher in the
second diary week, b=0.34, SE =0.12, t(1093) =2.76,
p=0.006 (0.09, 0.58), but there was no linear trend
over time, b=−0.02, SE =0.02, t(1093) =−1.20,
p=0.228 (−0.06, 0.02). As expected, there was no effect
of implicit theories about willpower on demands, b=0.13,
SE =0.10, t(152) =1.33, p=0.185 (−0.06, 0.32). This finding
replicates previous research showing that willpower theories
are not related to people’s demands (Job et al., 2015b). The
independence of the two constructs also allows testing effects
of their two-way interaction on expectations and effective goal
striving.
Do People with a Limited Theory Expect to Have
More Unpleasant Tasks, Particularly After a
Demanding Day?
No. We analyzed the effects of willpower theories on expectations
about the amount of unpleasant and pleasant tasks separately. In
each model, the main predictors were willpower theories,
previous day demands, and their two-way interaction.
Additionally, we controlled for effects of day, week, person
mean demands, same day demands, optimism, pessimism, and
self-efficacy.
In the first model, we predicted the expected amount of
unpleasant tasks. The random effect of previous day demands
was added, because it significantly improved the model fit, which
was tested with a likelihood ratio test, X2(2) =12.10, p=0.002.
Results are summarized in Table 2. The effect of willpower
theories on the amount of unpleasant tasks was not significant,
while the effect of previous day demands was significant.
Demands of the previous day increased the expected amount
of unpleasant tasks reported the next morning. The interaction
between willpower theories and previous day demands was not
significant. We ran the same set of analysis on the expected
amount of pleasant tasks, but the main effect of willpower theory
and previous day demands, as well as their interaction were not
significant, ts<1. As expected, willpower theories did not affect
TABLE 2 | Linear multilevel model predicting expected amount of, progress in, and exhaustion from unpleasant tasks.
Expected amountaExpected progressbExpected exhaustionc
95% CI 95% CI 95% CI
Vari able bSE plower upper bSE plower upper bSE plower upper
Intercept 1.45 0.19 0.000 1.07 1.84 3.82 0.19 0.000 3.45 4.20 2.79 0.20 0.000 2.41 3.17
Day 0.02 0.02 0.249 −0.02 0.07 −0.04 0.02 0.088 −0.09 0.01 −0.04 0.03 0.100 −0.09 0.01
Week 0.32 0.12 0.007 0.09 0.55 0.09 0.14 0.503 −0.17 0.36 0.48 0.14 0.001 0.19 0.76
Optimism −0.06 0.07 0.355 −0.19 0.07 −0.03 0.06 0.677 −0.15 0.10 −0.04 0.06 0.538 −0.17 0.09
Pessimism 0.03 0.07 0.707 −0.11 0.16 −0.02 0.07 0.766 −0.15 0.11 −0.08 0.07 0.220 −0.21 0.05
Self-efficacy −0.19 0.13 0.139 −0.44 0.06 0.26 0.12 0.037 0.02 0.51 −0.08 0.12 0.536 −0.32 0.17
Person mean
demands
0.31 0.08 0.000 0.16 0.46 −0.02 0.08 0.839 −0.16 0.13 0.24 0.08 0.002 0.10 0.39
Same day demands 0.03 0.03 0.358 −0.03 0.08 0.02 0.03 0.581 −0.04 0.08 0.08 0.03 0.016 0.02 0.15
Previous day
demands
0.07 0.03 0.030 0.01 0.13 0.04 0.03 0.167 −0.02 0.11 0.06 0.03 0.108 −0.01 0.12
Willpower theory 0.09 0.10 0.320 −0.09 0.28 −0.13 0.09 0.161 −0.32 0.05 0.08 0.09 0.392 −0.10 0.26
Willpower theory∗
Previous day
demands
0.09 0.06 0.140 −0.03 0.21 −0.13 0.06 0.027 −0.25 −0.02 0.16 0.06 0.012 0.04 0.29
Variance components
Intercept (SD) 0.38 0.29 0.49 0.38 0.31 0.47 0.22 0.10 0.52
Demands (SD) 0.15 0.08 0.27 −−−−−−
Residual (SD) 0.72 0.67 0.77 0.77 0.72 0.81 0.89 0.83 0.95
Correlation −0.27 −0.74 0.37 −−−−−−
adfwithin =145, dfbetween =687; bdfwithin =145, dfbetween =669; cdfwithin =145, dfbetween =674.
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Bernecker and Job Willpower theories and previous day demands
the expectations about the amount of unpleasant or pleasant
tasks.
Do People with a Limited Theory Expect to Make
Less Progress in Unpleasant Tasks, Particularly After
a Demanding Day?
Yes. We predicted the expected progress in unpleasant tasks with
the same predictors as used in the previous model. The random
effect of demands did not improve the model fit, X2(2) =1.48,
p=0.476, and was therefore removed. As summarized in Table 2,
there was no significant main effect of willpower theories, nor
of previous day demands. However, the interaction between
willpower theory and previous day demands was significant. The
pattern of the interaction is depicted in Figure 1.Weconducted
simple slope analyses using a commonly used computational tool
(Preacher et al., 2006), which probes 2-way interaction effects
for hierarchical linear models and provides a z-test statistic for
each slope at a conditional value of the moderator. The analysis
showed that following a demanding day (+1SD)therewasa
significant difference in expected progress between people with a
limited and non-limited theory, b=−0.27, SE =0.11, z=−2.44,
p=0.015. There was no difference following non-demanding
days (−1SD), z<1, ns. People with a nonlimited theory (−1SD)
expected to make more progress after a demanding day than after
a non-demanding day, b=0.12, SE =0.04, z=2.82, p=0.005,
whilepeoplewithalimitedtheory(+1SD) did not differ in their
expectations, z<1, ns. We ran the same analysis for expected
progress on pleasant tasks, but there were no main effects of
willpower theory or previous day demands, and the interaction
was also not significant, ts<1.19, ns.
Do People with a Limited Theory Expect to be More
Exhausted from Unpleasant Tasks, Particularly After
a Demanding Day?
Yes. We predicted the expected exhaustion with the same
variables as in the previous two models. As summarized
FIGURE 1 | Expected progress in unpleasant tasks predicted by
willpower theory and previous day demands. Error bars show ±1SE.
in Tab l e 2 , there was no main effect of willpower theories
or previous day demands. However, there was a significant
interaction effect. The pattern of the interaction is depicted
in Figure 2. Simple slope analyses showed that following a
demanding day (+1SD) people with a limited theory (+1
SD) expected to be more exhausted from unpleasant tasks
than people with a non-limited theory (−1SD), b=0.29,
SE =0.11, z=2.65, p=0.008. There was no significant
difference in expected exhaustion following non-demanding days
(−1SD), z<1, ns. Further, people with a limited theory
expected to be more exhausted from unpleasant tasks following
a demanding day (+1SD) than following a non-demanding day
(−1SD), b=0.13, SE =0.05, z=2.83, p=0.005. Among
people with a non-limited theory, the expected exhaustion was
low independent of previous day demands, z<1, ns. The
same model was used to predict expected exhaustion from
pleasant tasks. Neither the main effects of willpower theories,
nor previous day demands, or the interaction were significant,
ts<1.13, ns.
Are People with a Limited Theory Less Effective in
Goal Striving, Particularly After a Demanding Day?
Yes. We predicted the overall effective goal striving on a
day using the same variables as in the previous models.
The results are summarized in Table 3.Therewasnomain
effect of willpower theory, but a significant effect of previous
day demands. Following a demanding day, people were more
productive. However, the effect was moderated by willpower
theories. The pattern of the interaction is depicted in Figure 3.
Simple slope analysis showed that after a demanding day (+1
SD) people with a non-limited theory (−1SD) reported more
effective goal striving than people with a limited theory (+1
SD), b=−0.32, SE =0.13, z=−2.51, p=0.012. After a
non-demanding day, there was no difference in effective goal
striving, z<1, ns. People with a non-limited theory showed
more effective goal striving following a demanding day than
following a non-demanding day, b=0.18, SE =0.05, z=3.34,
p=0.001. For people with a limited theory goal striving was
overall less effective independent of previous day demands,
z<1, ns.
Do Expectations Mediate the Effects of Willpower
Theories and Previous Day Demands on Effective
Goal Striving?
No. We tested whether the effect on effective goal striving was
mediated by expectations and included expectations about the
amount of unpleasant tasks, progress, and exhaustion (all person-
mean centered) in the model. Effective goal striving was positively
associated with the expected number of unpleasant tasks,
b=0.13, SE =0.05, t(662) =2.80, p=0.005, and expectations of
progress, b=0.19, SE =0.04, t(662) =4.91, p<0.001. Expected
exhaustion from unpleasant tasks was not significantly related
to goal striving, b=0.04, SE =0.04, t(662) =1.11, p=0.266.
Although expectations explained some variance in goal striving
the effect of the interaction between willpower theories and
previous day demands remained significant when expectations
were controlled, b=−0.12, SE =0.06, t(662) =−2.05, p=0.041.
Frontiers in Psychology | www.frontiersin.org 6October 2015 | Volume 6 | Article 1496

Bernecker and Job Willpower theories and previous day demands
FIGURE 2 | Expected exhaustion from unpleasant tasks predicted by
willpower theory and previous day demands. Error bars show ±1SE.
This finding suggests that expectations cannot account for the
effect of willpower theories on effective goal striving.
Discussion
Previous studies found that people with a limited theory show
lower self-regulation with respect to a challenging goal when
self-regulatory demands are high (Job et al., 2010). The aim
of the present diary study was to examine whether willpower
theories also moderate the effect of within-person changes
TABLE 3 | Linear multilevel model predicting effective goal striving.
Effective goal striving
95% CI
Vari able bSE plower upper
Intercept −0.15 0.18 0.384 −0.50 0.19
Day −0.05 0.02 0.014 −0.10 −0.01
Week 0.40 0.13 0.001 0.16 0.65
Optimism 0.12 0.06 0.054 0.00 0.23
Pessimism 0.02 0.06 0.710 −0.09 0.14
Self-efficacy 0.20 0.11 0.076 −0.02 0.42
Person mean demands 0.08 0.07 0.256 −0.06 0.22
Same day demands 0.04 0.03 0.165 −0.02 0.10
Previous day demands 0.07 0.03 0.018 0.01 0.13
Willpower theory −0.15 0.09 0.082 −0.32 0.02
Willpower theory∗Previous
day demands
−0.14 0.06 0.014 −0.25 −0.03
Variance components
Intercept (SD) 0.36 0.30 0.44
Residual (SD) 0.75 0.71 0.79
dfwithin =147, dfbetween =752.
FIGURE 3 | Effective goal striving predicted by willpower theory and
previous day demands. Error bars show ±1SE.
in demands on effective goal striving. We found that people
with a non-limited theory reported more effective goal striving
than people with a limited theory when the previous day was
demanding. Additionally, we examined the role of day-specific
expectations (reported in the morning) and general expectations
(i.e., optimism, pessimism, self-efficacy). We predicted that day-
specific expectations mediate effects of willpower theories on
effective goal striving (reported retrospectively in the evening).
As expected, a limited theory predicted lower expectations
regarding progress on unpleasant tasks (but not on pleasant
tasks) and higher expected exhaustion from unpleasant tasks
(but not on pleasant tasks) if the previous day was demanding.
Although morning expectations were related to effective goal
striving they did not mediate the effect of willpower theories and
previous day demands. In sum, the findings replicate previous
findings suggesting that willpower theories affect self-control
when demands accumulate (Job et al., 2010, 2015b). Thereby, the
present study also contributes to the current discussion in the
self-control literature and supports alternative perspectives that
provide motivational rather than resource-focused explanations
for self-control failure (Inzlicht and Schmeichel, 2012;Kurzban
et al., 2013;Inzlicht et al., 2014;Kool and Botvinick, 2014).
In the present study, we controlled for different variables
at the day-level and the person-level to rule out alternative
explanations. First, we controlled for persons’ mean level of
demands and demands experienced on the day when participants
reported their expectations and their effective goal striving.
Further, previous day demands were person-mean centered. That
means, previous day demands reflect the increment of the person
experiencing more or less demands on a specific day than she
would on average and controlling for the effects of being a
person with generally high demands and the demands on the
very same day. Thus, we can rule out that the effects of the
previous day were due to people having more demands in general.
Further, it is very unlikely that reports of effective goal striving
were biased by people’s demands ratings, because the critical
Frontiers in Psychology | www.frontiersin.org 7October 2015 | Volume 6 | Article 1496

Bernecker and Job Willpower theories and previous day demands
demand measure was completed 24 hours before the effective goal
striving measure. Second, we controlled for people’s optimism,
pessimism, and their level of self-efficacy to assure that willpower
theories and not general expectations were driving the observed
effects. Although, people with a non-limited theory were more
optimistic, less pessimistic, and had higher self-efficacy, it was
not the shared variance betweenthese constructs that determined
the impact of previous day demands on morning expectations
and effective goal striving. Although, recent research suggests
that state self-efficacy explains why self-control performance
suffers from previous attempts to self-control (Chow et al., 2015),
general self-efficacy seems not to account for the effects of
willpower theories on everyday self-regulation. However, since
the study has a correlational design, we cannot rule out all
possible third variables that might account for the observed
effects, such as for instance achievement motivation. This would
only be possible with an experimental design were willpower
theories are manipulated. There are promising findings from lab
studies suggesting that willpower theories can be manipulated in
the short term (Job et al., 2010;Miller et al., 2012;Vohs et al.,
2013). However, longer term manipulation of willpower theories
in the field is still a challenge that remains for future research.
Previous field studies showed that particularly within times of
high demands, people’s willpower theory predicts how successful
they strive for their personal goals (Job et al., 2010). In the current
study we replicated these findings with within-persons variations
in daily demands. However, the pattern of the interaction
suggests a positive effect of demands for people with a non-
limited theory rather than a negative effect of demands for
people with a limited theory. This “energizing” pattern might
be explained by the fact that atypically people in the present
sample agreed more with a non-limited theory than with a limited
theory (Job et al., 2010, 2015a). The greater endorsement of a
non-limited theory in the present sample might also explain why
previous day demands were overall positively related to effective
goal striving on the next day and not negatively. As mentioned
earlier, a non-limited theory includes the idea that engaging
in strenuous tasks can activate one’s willpower and therefore
improve subsequent performance.
The finding that previous day demands in general were
related to more effective goal striving on the following day
is surprising, because previous research suggests that demands
lead to depletion-like effects causing less effective goal striving
(Baumeister and Heatherton, 1996;Oaten and Cheng, 2005).
The fact that demands can have positive and negative effects on
performance is also reflected in new models of stress. Although
the classic view on stress is that it undermines performance (e.g.,
Glass and Singer, 1972), more recent models propose different
types of stress, which have different effects on performance.
For instance, the Challenge-Hindrance-Modell (Cavanaugh et al.,
2000) suggests that stressors can be categorized either as challenge
stressors which promote performance (e.g., time pressure) or
hindrance stressors which harm performance (e.g., red tape).
Studies often measure these different types of stressors, which are
categorized a priori as challenge or hindrance stressors. However,
it has been argued that the pre-categorization of stressors ignores
the socio-cognitive approaches to stress, which conceptualize
stress as a function of a person’s appraisals (Edwards et al., 2014).
The effects of stressors on performance might depend on the
individual’s appraisal of the specific stressor as threat or challenge.
If a person perceives to have sufficient resources to cope with the
demands in his or her environment stressors might be perceived
as a challenge and promote rather than impair performance
(Edwards et al., 2014). The present study suggests that willpower
theories determine the impact of previous day demands on
next day’s self-regulatory performance. The appraisal of self-
regulatory demands as a challenge or hindrance might play an
important role in this context. When people believe that their
willpower is limited they might perceive to have not sufficient
resources to overcome demands on the next day. Future studies
should therefore investigate whether self-regulatory demands are
perceived differently when people endorse a limited or non-
limited theory.
An open question that remains from the present research
concerns the role of expectations. Although morning
expectations were related to effective goal striving the effect
of willpower theories and previous day demands remained
significant when expectations were controlled. One reason for
this finding might be that the measure of expectations did not
exactly match the measure for effective goal striving. Perhaps, the
proposed mediation would emerge if measures of expectations
and effective striving would both refer to the same goal or
unpleasant task. Future studies should therefore ask people in
the morning about the specific unpleasant task or goal for that
day and then assess their progress in that specific task or goal in
the evening. Due to this methodological limitation of the study,
we cannot rule out that expectations play a role in explaining
effects of willpower theories on different outcomes.
Recently, studies suggest that one part of the mechanism
might be different goals people strive for after they exerted self-
control (Job et al., 2015a). Following a self-control task, people
with a limited theory have the goal to rest and are more likely
to engage in resting behavior (Job et al., 2015a). However, the
pursuit of the goal to rest is not incompatible with different
expectations about future self-control performance. These two
mechanisms might go hand in hand. People with a limited theory
might expect to perform less well on future tasks because they
believe that their resources are depleted. Further, they might
pursue the goal to rest and replenish these resources in order
to increase their likelihood of performing well on the upcoming
task. Future field studies should assess both expectations and the
goal to rest following a demanding day.
We also want to mention some limitations of the study
with regard to the sample and the measures used. Because our
main interest was to test a conceptual hypothesis that willpower
theories affect goal striving and expectations in interaction with
previous demands we chose a homogenous student sample
for this study. The question, however, remains whether the
findings can be generalized to the general population and whether
they are affected by different variables such as age, culture,
or social class. Further, the use of self-report measures is a
limitation of the present study. Sampling behavioral data on
effective goal striving would be a great improvement for future
studies.
Frontiers in Psychology | www.frontiersin.org 8October 2015 | Volume 6 | Article 1496

Bernecker and Job Willpower theories and previous day demands
Conclusion
The present study supports James’ (1907)notionthatdaily
fluctuations in levels of energy might depend on people’s
motivation to exert their mental and physical resources. The
present findings suggest that beliefs about willpower determine
whether demands prompt people to save their energies and put
their goals on hold or whether they encourage them to lean in
and fully tap into their resources.
Author contributions
KB was involved in the conception and design of study, as
well as the collection, analysis, and interpretation of data.
Further, KB was involved in drafting the work and gave
final approval of the version to be published. KB gives
agreement to be accountable for all aspects of the work in
ensuring that questions related to the accuracy or integrity
of any part of the work are appropriately investigated and
resolved.
VJ was involved in the conception and design of
study, as well as the interpretation of data. Further, VJ
was involved in drafting and revising the work and gave
final approval of the version to be published. VJ gives
agreement to be accountable for all aspects of the work in
ensuring that questions related to the accuracy or integrity
of any part of the work are appropriately investigated and
resolved.
Acknowledgments
This research was funded by the Swiss National Science
Foundation (grant number PZ00P1_131858) and the Stiftung
Suzanne und Hans Biäsch zur Förderung der Angewandten
Psychologie (Foundation Suzanne and Hans Biäsch for the
Advancement of Applied Psychology).
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Conflict of Interest Statement: The authors declare that the research was
conducted in the absence of any commercial or financial relationships that could
be construed as a potential conflict of interest.
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