«Katherine L. Milkman Julia A. Minson Kevin G.M. Volpp The Wharton School, University of Pennsylvania Last Revised: June 6, 2013 Abstract: We ...»
Holding the Hunger Games Hostage at the Gym:
An Evaluation of Temptation Bundling
Katherine L. Milkman Julia A. Minson Kevin G.M. Volpp
The Wharton School, University of Pennsylvania
Last Revised: June 6, 2013
Abstract: We introduce and evaluate the effectiveness of temptation bundling – a method for
simultaneously tackling two types of self-control problems by harnessing consumption
complementarities. We describe a field experiment measuring the impact of bundling instantly-gratifying but guilt-inducing “want” experiences (enjoying page-turner audiobooks) with valuable “should” behaviors providing delayed rewards (exercising). We explore whether such bundles increase should behaviors and whether people would pay to create these restrictive bundles. Participants were randomly assigned to a full treatment condition with gym-only access to tempting audio novels, an intermediate treatment involving encouragement to restrict audiobook enjoyment to the gym, or a control condition.
Initially, full and intermediate treatment participants visited the gym 51% and 29% more frequently, respectively, than control participants, but treatment effects declined over time (particularly following Thanksgiving). After the study, 61% of participants opted to pay to have gym-only access to iPods containing tempting audiobooks, suggesting demand for this commitment device.
Keywords: commitment devices; temptation bundling; self-control; field experiment Acknowledgements: We thank the Pottruck Health & Fitness Center and Wharton Behavioral Lab for their assistance with this project. We are particularly grateful to Elizabeth Herrick, Amy Wagner, Kaity Moore and Young Lee as well as our Research Assistants Samantha Lee, Benjamin Kirby, Daniel Milner and Alexander Rogala. We also thank Max Bazerman, Barbara Mellers, Klaus Wertenbroch, Uri Simonsohn, and participants at the SCP Winter 2013 Conference as well as the CMU-Penn 2010 and 2012 Roybal Center Retreats for their insightful feedback on this research. Finally, we thank the Wharton Dean’s Research Fund, the Wharton Behavioral Lab, the Penn-CMU Roybal Center on Behavioral Economics and Health (NIA 1P30AG034546-01), and the NBER Roybal Center for Behavior Change in Health and Saving (NIH P30AG034532) for funding support.
1. Introduction With 68% of adult Americans overweight or obese as of 2008 (Flegal, Carroll, Ogden, & Curtin,
2010) and 112,000 deaths in the United States per year attributable to obesity (Flegal, Graubard, Williamson, & Gail, 2007), promoting weight loss is an urgent public health priority. Further, in light of skyrocketing healthcare costs caused in part by obesity, programs designed to encourage weight loss are of tremendous interest to most organizations (Finkelstein, Fiebelkorn, & Wang, 2005; Finkelstein, daCosta DiBonaventura, Burgess, & Hale, 2010). Despite the many benefits that exercise provides, including promoting weight loss (Andersen, 2010), only 50% of Americans exercise sufficiently, a percentage that has been steadily declining ("U.S. Physical Activity Statistics," 2007).
Recent research has highlighted the possibility that public policy interventions built on an understanding of the psychology surrounding the challenges associated with increasing physical activity may be particularly effective. For example, groundbreaking research conducted in the last several years has shown that incentivizing exercise is not only an effective way to increase physical activity, but that incentivizing repeated gym attendance can produce long-lasting exercise habits that remain after incentives are removed (Charness and Gneezy, 2009; Acland and Levy, 2011). This work underscores the value of taking both economics and psychology into account when seeking to increase exercise rates.
If low exercise rates are in part the result of self-control problems, as much past research suggests (see for example Della Vigna and Malmandier (2006)), interventions that use psychological tools and insights to tackle this obstacle may be particularly valuable and cost-effective. Limited willpower has been shown to play an important role in decisions made by individuals that affect weight gain, such as healthy eating and exercise: people intend to exercise and diet tomorrow but frequently lack the necessary willpower to act on those good intentions today (Della Vigna & Malmendier, 2006; Milkman, Rogers, & Bazerman, 2009; Read & van Leeuwen, 1998; Royer, Stehr, & Sydnor, 2012). On the other hand, limited willpower makes it difficult for individuals to resist engaging in many highly tempting behaviors involving indulgences that induce regret after-the-fact (for a review, see Milkman, Rogers, & Bazerman (2008)).
We propose that valuable, healthy behaviors could be increased while guilt and wasted time from
indulgent behaviors are simultaneously decreased through the use of a previously unstudied intervention:
“temptation bundling.” Temptation bundling involves the coupling of instantly gratifying “want” activities (e.g., watching the next episode of a habit-forming television show, checking Facebook, receiving a pedicure, eating an indulgent meal) with engagement in a “should” behavior that provides long-term benefits but requires the exertion of willpower (e.g., exercising at the gym, completing a paper review, spending time with a difficult relative). For example, imagine only allowing yourself to: enjoy the next episode of your favorite TV show while exercising, receive a pedicure while completing an
-2overdue manuscript review, or indulge in the burger you crave when spending time with your cranky uncle. Temptation bundling can solve two problems at once by increasing the desire of those with selfcontrol problems to engage in beneficial behaviors requiring willpower, and reducing the likelihood that people will engage in indulgent activities that they will later regret. Temptation bundling may be particularly effective because it exploits complementarities that often exist between wants and shoulds to create added value. The simultaneous engagement in wants and shoulds can reduce the guilt associated with indulgences and offer a distraction from the unpleasantness of many beneficial activities.
We theorize that people with limited willpower who are aware of their self-control problems (“sophisticates” (O'Donoghue & Rabin, 1999)) would gain from and value an opportunity to force their future selves to engage in beneficial should activities while simultaneously preventing those future selves from indulging in pleasurable but ultimately guilt-inducing want activities. We test a previously unexplored method for enforcing these preferences by creating a temptation bundling program that bundles a highly tempting activity (listening to low-brow, page-turner audio novels) with an activity that requires exerting self-control (exercising).1 By bundling access to a hedonic experience with exercise, exercise is made “tempting” and increasingly appealing, while the squandering of time and resources on a potentially regret-inducing indulgent activity is prevented. In short, the inverted shapes of the utility streams obtained from engaging in want and should behaviors are strategically combined by temptation bundling. This insures that those who discount the future heavily will engage in shoulds and will limit their engagement in wants to moments when the downstream negative consequences (e.g., guilt and wasted time) are minimized if not eliminated (see Figure 1).
In the present investigation we focus on two questions pertaining to the value of “temptation bundling.” First, our field experiment examines whether temptation bundling programs have the potential to induce behavior change, setting aside the question of whether individuals would be “sophisticated” enough about their self-control problems to voluntarily seek out such programs (O'Donoghue & Rabin, 1999). Answering this first question allows us to establish whether the temptation bundling idea has value. We do this by measuring the effectiveness of temptation bundling as a means of increasing exercise frequency. We also examine whether individuals are able to effectively self-impose a suggested temptation bundling rule. Previous research on mental accounting and goal setting indicates that without external referees, people often (though not always: see Burger, Charness and Lynham, 2011) have the capacity to adhere to pre-determined rules designed to mitigate self-control problems (Abeler & Marklein, 1 Note that exercise does not fit the definition of a should for all individuals, nor does listening to lowbrow audio novels universally fit the definition of a want. However, we follow past want/should research that defines goods and experiences as wants and shoulds based on the attitudes of most individuals (see for example Milkman, Rogers, & Bazerman, 2009).
-3Camerer, Babcock, Loewenstein, & Thaler, 1997; Cheema & Soman, 2008; Heath, Larrick, & Wu, 1999; Milkman & Beshears, 2009; Shefrin & Thaler, 1988; R. Thaler, 1985; R. H. Thaler, 1990, 1999; R.
H. Thaler & Shefrin, 1981). By including an intermediate intervention in our experiment to test the effectiveness of suggested temptation bundling, we are able to disentangle the effectiveness of merely giving people the insight regarding the potential value of this technique from that of creating a structured environment that limits their ability to behave myopically.
The second question we address is whether individuals are willing to restrict their own behavior in order to garner the benefits of temptation bundling. We investigate this critical question after first establishing the power of temptation bundling to change behavior in our field experiment. Measuring willingness to pay for temptation bundling devices is important because non-zero willingness to pay would be crucial for widespread adoption of temptation bundling without government or employer incentives, suggesting a potential market in which for-profit entities could package and sell these types of commitment devices. This second question is further of considerable theoretical interest, as evidence of a non-zero willingness to pay would add to the mounting literature contradicting the neoclassical economic models of behavior whereby rational actors see no value in restricting their future selves.
Indeed, past research has demonstrated that people value mechanisms that prevent their future selves from making unwise decisions such as procrastinating (Ariely & Wertenbroch, 2002), under-saving (Ashraf, Karlan, & Yin, 2006; Beshears, Choi, Laibson, Madrian, & Sakong, 2011), smoking cigarettes (Giné, Karlan, & Zinman, 2010), failing to achieve workplace goals (Kaur, Kremer, & Mullainathan, 2010), and giving into repeated temptations in the laboratory (Houser, Schunk, Winter, & Xiao, 2010).
Study participants have expressed a willingness to use “commitment devices” such as placing money in restrictive accounts that prevent premature savings withdrawals (Ashraf et al., 2006; Beshears et al., 2011); self-imposing deadlines with associated late penalties to prevent procrastination on coursework (Ariely & Wertenbroch, 2002); and placing money on the line for forfeiture if they fail to quit smoking, exercise or lose weight (Halpern, Asch, & Volpp, 2012; John, Loewenstein, & Volpp, 2012; Royer et al., 2012; Volpp et al., 2008).
Conceptually, temptation bundling devices are a previously unstudied form of commitment device with several distinct features. First, temptation bundling devices do not require monetary transfers (or any other form of punishment) between the user and an outside entity. Rather than imposing a cost on individuals who break commitments to exert self-control, a temptation bundling device makes the activity whose pursuit requires willpower more alluring. Second, temptation bundling may be particularly effective if complementarities exist between a temptation item and the healthy behavior it is bundled with.
For example, complementarities may exist between exercising and listening to tempting audio novels such that exercising while listening to fiction may create more net utility than that created from engaging
-4in both activities separately. Third, to the extent that the tempting activities bundled with should behaviors are habit-forming, they may be particularly powerful motivators (Solomon & Corbit, 1974). In other words, individuals may be particularly eager to return to the gym to hear the next chapter of their novel or to view the next episode of a television show after a cliffhanger. Finally, previous psychology research has suggested that engaging in healthy behaviors like exercise depletes willpower, which is a finite resource (Baumeister, Bratslavsky, Muraven, & Tice, 1998; M. Muraven, Tice, & Baumeister, 1998; Mark Muraven & Baumeister, 2000), while engaging in indulgences has the opposite, repleting effect.2 Temptation bundling may be particularly effective if giving into a temptation increases an individual’s available willpower, making the net impact of exercise on willpower less depleting (and potentially even positive).
2. Research Overview To investigate our first research question – whether temptation bundling can create value – we conducted a three-condition randomized, controlled trial in collaboration with a large University fitness facility. Participants were randomly assigned to one of three experimental conditions and their frequency of gym attendance was measured. In the full treatment condition, participants were given access to an iPod containing four “want” audio novels of their choice that they could only listen to at the gym. In the intermediate treatment condition, participants were also given access to four “want” audio novels of their choice, but these novels were loaded onto their personal iPods, which they could access at any time.
These participants were encouraged to try self-imposing a rule whereby they only allowed themselves to enjoy audio novels while exercising. Finally, in the control condition, participants were given a $25 Barnes and Noble gift certificate at the start of the study (valued equivalently to the loan of four audio novels, see 2.2 Procedures).