Anselme & Güntürkün (A&G) present a mechanistic explanation for the enhanced foraging behavior observed in animals living under conditions of uncertainty. This commentary examines how their “incentive hope” hypothesis might also explain related phenomena based on behavioral observations in humans. In particular, we suggest that the greater rates of impulsive decision making associated with people in low-socioeconomic-status (SES) environments may stem from the relative resource scarcity they experience and the subsequent uncertainty of their future stability. We also describe some implications of this theoretical effort in addressing wealth inequality and promoting adaptive decision making in low-SES populations.

In modern society, impatience and impulsivity, where individuals pursue immediate gratification rather than long-term rewards, can have a significant impact on daily life decisions. Important examples include saving enough for retirement (Laibson et al. Reference Laibson, Repetto, Tobacman, Hall, Gale and Akerlof1998), investing in higher education (Castillo et al. Reference Castillo, Ferraro, Jordan and Petrie2011; Eckel et al. Reference Eckel, Johnson and Montmarquette2013), buying on impulse and accruing credit debt (Meier & Sprenger Reference Meier and Sprenger2010; Reference Meier and Sprenger2013), and obesity (Courtemanche et al. Reference Courtemanche, Heutel and McAlvanah2015; de Oliveira et al. Reference de Oliveira, Leonard, Shuval, Skinner, Eckel and Murdoch2016). A growing amount of evidence indicates that impulsive decision making is more prevalent among people in low-SES environments and is connected to a constellation of negative outcomes. For example, societies with significant income inequality, that is, Gini coefficients greater then 0.5, have higher rates of obesity and type II diabetes (Wilkinson & Pickett Reference Wilkinson and Pickett2011). There are also a greater number of low-income individuals taking out short-term, high-interest loans (Bair Reference Bair2005). This characteristic pattern of impulsivity has been systematically studied in the laboratory. Participants who are experimentally induced to experience low-SES indicators in terms of income or job types choose foods with higher caloric intake (Cheon & Hong Reference Cheon and Hong2017), make riskier financial decisions (Burdick et al. Reference Burdick, Roy and Raver2013; Payne et al. Reference Payne, Brown-Iannuzzi and Hannay2017; Shah et al. Reference Shah, Mullainathan and Shafir2012), and demonstrate greater impulsive spending (Yoon & Kim Reference Yoon and Kim2016). These findings introduce an apparent paradox: Why would individuals experiencing so much difficulty in their lives engage in greater amounts of impulsive behavior that increases their vulnerability?

One explanation for the greater levels of impulsivity found in low-SES groups is consistent with the incentive hope hypothesis, which focuses on the impact of resource scarcity in the surrounding environment. We believe that the life experiences and relative deprivation that people struggling with economic hardship face engenders a feeling of uncertainty and insecurity toward the future, which in turn motivates more impulsive resource-seeking behavior. The relationship between one's future prospects and impulsive decision making has often been studied via temporal discounting tasks, in which participants are asked to choose between receiving a smaller monetary amount sooner or a larger amount later. Studies have shown that discounting rates, which could be interpreted as a measure of impulsivity, can change by making people think more about their future (Appelt et al. Reference Appelt, Milch, Handgraaf and Weber2011; Brown et al. Reference Brown, Ivković and Weisbenner2015; Hershfield et al. Reference Hershfield, Goldstein, Sharpe, Fox, Yeykelis, Carstensen and Bailenson2011; Weber et al. Reference Weber, Johnson, Milch, Chang, Brodscholl and Goldstein2007). In general, people become less impulsive when prompted to think toward the future. However, future prospects are not equally bright for people in low-SES environments who face multiple challenges and ongoing struggles in their lives. Several studies have shown that poverty distorts an individual's mindset to be focused on the present and have distrust toward the future (Farah & Hook Reference Farah and Hook2017; Haushofer & Fehr Reference Haushofer and Fehr2014; Shafir Reference Shafir2017; Shah et al. Reference Shah, Mullainathan and Shafir2012). To directly test how having negative future prospects can change an individual's intertemporal choice, we recently conducted an experiment in which participants were primed with either a positive and promising or a negative and unstable future prospect in an economic, geopolitical, and environmental domain. We found that the negative future primes increased discounting rates relative to baseline measures, whereas no such effect was found with positive primes (Kwak et al. Reference Kwak, Walsh, Chen, Cheries and Ya2017). These results indicate that the way one's future is perceived can have a significant impact on how individuals trade off present and future consumption.

In the wild, the link between impulsivity and future uncertainty is most evidently shown under harsh environments; animals hoard and consume more food when exposed to an unpredictable food supply. A&G provide a mechanistic explanation for this, focusing on how the brain's motivational system changes when subjected to resource scarcity. Specifically, they describe how unpredictable access to resources enhances “incentive hope,” which manifests as an increase in seeking behavior and a greater motivational drive toward consumption. In humans, individuals in low-SES environments may experience comparable circumstances that trigger a similar response – limited access to resources contributes to an overall sense of uncertainty about one's future prospects. Facing repeated hardship and unpredictability in this way may result in a similar shift in the brain's motivational system. Overall, this increasing motivational drive might manifest itself in terms of both an immediate increase in the consumption of resources and a cascade of problematic behaviors such as substance use and pathological gambling, which are both more prevalent in these vulnerable populations (Casswell et al. Reference Casswell, Pledger and Hooper2003; Hiscock et al. Reference Hiscock, Bauld, Amos, Fidler and Munafò2012).

Understanding the nature of impulsivity in low-SES groups in terms of incentive hope also helps motivate potential interventions that may help mitigate some of the negative consequences of impulsive decision making, ranging from financial debt to obesity and other addiction-related outcomes. Specifically, if the feeling of unpredictability or uncertainty toward the future is what triggers greater incentive hope and a maladaptive motivational drive, we can start by focusing on mediations that build trust and reliability. A recent real-world intervention study demonstrates that providing a supportive social environment by promoting community trust can reduce impulsive decision making in low-income individuals as measured through temporal discounting (Jachimowicz et al. Reference Jachimowicz, Chafik, Munrat, Prabhu and Weber2017). These results are particularly intriguing as prior research indicates that low-SES individuals, in general, have less trust in society (Brandt et al. Reference Brandt, Wetherell and Henry2015; Sirola & Pitesa Reference Sirola and Pitesa2017). Future research should address ways to effectively enhance trust and reduce feelings of future uncertainty in our world's most susceptible groups. Increased focus on mechanistic explanations such as that proposed in the target article will, it is hoped, lead to more practical solutions to help mitigate the long-running wealth and health inequalities that societies face around the world.