Theories of Willpower Affect Sustained Learning Eric M. Miller1*, Gregory M. Walton 1 , Carol S. Dweck1, Veronika Job 2 , Kali H. Trzesniewski3, Samuel M. McClure1 1 Department of Psychology, Stanford University, Stanford, California, United States of America, 2 Department of Psychology, University of Zurich, Zurich, Switzerland, 3 Department of Psychology, University of California Davis, Davis, California, United States of America Abstract Building cognitive abilities often requires sustained engagement with effortful tasks. We demonstrate that beliefs about willpower–whether willpower is viewed as a limited or non-limited resource–impact sustained learning on a strenuous mental task. As predicted, beliefs about willpower did not affect accuracy or improvement during the initial phases of learning; however, participants who were led to view willpower as non-limited showed greater sustained learning over the full duration of the task. These findings highlight the interactive nature of motivational and cognitive processes: motivational factors can substantially affect people’s ability to recruit their cognitive resources to sustain learning over time. Citation: Miller EM, Walton GM, Dweck CS, Job V, Trzesniewski KH, et al. (2012) Theories of Willpower Affect Sustained Learning. PLoS ONE 7(6): e38680. doi:10.1371/journal.pone.0038680 Editor: Joy J. Geng, University of California, Davis, United States of America Received October 11, 2011; Accepted May 8, 2012; Published June 22, 2012 Copyright: 2012 Miller et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: The experiment was funded by Stanford University and a grant from the Givaudan Corporation (SMM). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: ermiller@stanford.edu Introduction Acquiring new cognitive abilities often requires sustained, effortful engagement with challenging tasks. Evidence suggests that even for the most talented individuals, becoming an expert in a new domain can require over 10,000 hours of training [1]. Because of these steep requirements, the ability to persist in cognitively demanding tasks is crucial for achievement in many fields. We demonstrate that beliefs about the nature of willpower can promote or hinder learning on a strenuous mental task that taxes working memory. Recent findings have highlighted the pronounced role that implicit theories about the nature of intelligence and personality traits play in shaping behavior [2,3]. Most relevant to the current study, implicit theories about willpower have been shown to moderate the extent to which self-control suffers following a demanding mental task [4]. Those participants who held, or were primed to hold, a ‘‘limited resource theory’’–that is, who viewed, or were led to view, willpower as dependent on a resource that is easily be depleted through mental exertion–showed worse response inhibition and performance following a task with strong self-control demands. In contrast, holding the belief that mental exertion can be energizing (what we refer to as the ‘‘non-limited resource theory’’) eliminated these deficits. If the non-limited resource theory has a relative positive effect on people’s ability to sustain self-control, might these theories comparably affect cognitive growth in situations where learning requires sustained persistence on a strenuous task? We assess this by manipulating implicit theories about willpower and measuring sustained learning–improvement in performance (i.e., accuracy) over a series of trials on an extended, continuously challenging task that taxes working memory (see also [5]). Given the substantial attentional demands of this task, we predicted that participants primed to view willpower as relying on a limited resource would be less able to maintain the focus necessary to sustain learning compared to participants primed to view willpower as non-limited. Methods Fifty-six college students were randomly assigned to the ‘‘limited’’ or ‘‘non-limited’’ willpower group. Written informed consent was obtained from all participants, and the study was approved by the Institutional Review Board at Stanford University. Following past research, implicit theories about willpower were manipulated through 8-item biased question- naires intended to elicit agreement with one or the other theory about willpower [4] (see Text S1 for the full list of items contained in the questionnaires). For example, participants assigned to the limited resource theory group rated their agreement with items such as, ‘‘Working on a strenuous mental task can make you feel tired such that you need a break before accomplishing a new task.’’ Participants assigned to the non- limited resource theory group rated their agreement with items such as, ‘‘Sometimes, it is energizing to be fully absorbed with a demanding task.’’ Participants responded to each item on a 4- point scale with 4 indicating maximum agreement. In each group, participants expressed strong agreement with the items (Figure S1; Mlimited = 3.27, and Mnon-limited = 3.03; scale mid- point = 2.50), one-sample ts.6.80, ps,1027). The primary dependent measure was performance on a 20- minute (540 trial) spatial 3-back task. On each trial, an X appeared on the screen in one of four locations for 0.5 seconds. Participants were instructed to press one of four buttons, corresponding to the location of the stimulus that appeared three trials before the present trial. Successful performance required continuous updat- ing and maintenance of working memory. Improvement in performance over time constituted our measure of sustained learning. PLoS ONE | www.plosone.org 1 June 2012 | Volume 7 | Issue 6 | e38680