We all know that food shopping when hungry is a bad idea but new research from the University of Dundee suggests that people might want to avoid making any important decisions about the future on an empty stomach.
The study, carried out by Dr. Benjamin Vincent from the University’s Psychology department, found that hunger significantly altered people’s decision-making, making them impatient and more likely to settle for a small reward that arrives sooner than a larger one promised at a later date.
Participants in an experiment designed by Dr. Vincent were asked questions relating to food, money and other rewards when satiated and again when they had skipped a meal.
While it was perhaps unsurprising that hungry people were more likely to settle for smaller food incentives that arrived sooner, the researchers found that being hungry actually changes preferences for rewards entirely unrelated to food.
This indicates that a reluctance to defer gratification may carry over into other kinds of decisions, such as financial and interpersonal ones. Dr. Vincent believes it is important that people know that hunger might affect their preferences in ways they don’t necessarily predict.
There is also a danger that people experiencing hunger due to poverty may make decisions that entrench their situation.
“We found there was a large effect, people’s preferences shifted dramatically from the long to short term when hungry,” he said.
“This is an aspect of human behaviour which could potentially be exploited by marketers so people need to know their preferences may change when hungry.
“People generally know that when they are hungry they shouldn’t really go food shopping because they are more likely to make choices that are either unhealthy or indulgent.
Our research suggests this could have an impact on other kinds of decisions as well.
Say you were going to speak with a pensions or mortgage advisor – doing so while hungry might make you care a bit more about immediate gratification at the expense of a potentially more rosy future.
“This work fits into a larger effort in psychology and behavioural economics to map the factors that influence our decision making.
This potentially empowers people as they may forsee and mitigate the effects of hunger, for example, that might bias their decision making away from their long term goals.”
Dr. Vincent and his co-author and former student Jordan Skrynka tested 50 participants twice – once when they had eaten normally and once having not eaten anything that day.
For three different types of rewards, when hungry, people expressed a stronger preference for smaller hypothetical rewards to be given immediately rather than larger ones that would arrive later.
The researchers noted that if you offer people a reward now or double that reward in the future, they were normally willing to wait for 35 days to double the reward, but when hungry this plummeted to only 3 days.
The work builds on a well-known psychological study where children were offered one marshmallow immediately or two if they were willing to wait 15 minutes.
Those children who accepted the initial offering were classed as more impulsive than those who could delay gratification and wait for the larger reward.
In the context of the Dundee study, this indicates that hunger makes people more impulsive even when the decisions they are asked to make will do nothing to relieve their hunger.
“We wanted to know whether being in a state of hunger had a specific effect on how you make decisions only relating to food or if it had broader effects, and this research suggests decision-making gets more present-focused when people are hungry,” said Dr. Vincent.
“You would predict that hunger would impact people’s preferences relating to food, but it is not yet clear why people get more present-focused for completely unrelated rewards.
“We hear of children going to school without having had breakfast, many people are on calorie restriction diets, and lots of people fast for religious reasons.
Hunger is so common that it is important to understand the non-obvious ways in which our preferences and decisions may be affected by it.”
The research is published in the latest edition of the journal Psychonomic Bulletin & Review.
In their daily lives, people are frequently confronted with self-control dilemmas requiring them to choose between an immediate but small reward or a larger reward in the long run. 
Opting for a small reward when a bigger one is available can be regarded as self-control failure, even when the bigger one is delayed.
Yet, many people tend to engage in this kind of disadvantageous choices, such as weight watchers who prefer a high caloric muffin for breakfast over a slim waist or business men preferring a night out at the casino over preparing next day’s meeting.
Indeed, an overwhelming amount of evidence exists indicating that people become more impulsive and opt for immediate gratification of their desires when they are emotional, hungry, sexually aroused or otherwise in a hot state.
For example, sexually aroused people engage in more impulsive decision making about sexual encounters, even when aware of the potential negative consequences. 
These findings make sense when considering that hot states in general, and visceral drives in particular, are adaptive physiological states that increase the motivation to satisfy important immediate (physical) needs, such as drinking water when thirsty. 
However, these urges become problematic when they are in conflict with a long term-goal, such as indulging in food when someone has a goal of weight watching or engaging in incidental sexual encounters when one has the goal of being faithful in a marital relationship.
Moreover, and potentially even more problematic, visceral states do not only affect motivation for rewards corresponding with the drive (e.g., getting food when hungry) but also may generalize to unrelated rewarding behaviors, such as when people report a stronger desire for money when hungry  or become more impulsive when sexually aroused .
There thus seems to be consensus that visceral drives and other hot states make people myopic for the future’ and hurt their long-term interests. .
Despite the apparent evidence that hot states compromise advantageous decision making, most studies so far have examined decisions about satisfaction of immediate needs in simple decision contexts where the potential long-term consequences are relatively straightforward.
In contrast, there is initial evidence suggesting that hot states may not compromise but rather facilitate advantageous decision making when these decisions are complex and long-term outcomes are uncertain, such as when delayed benefits are involved. In this kind of situations one cannot always rationally deliberate on multiple alternatives and reflect on their future consequences; other sources of information, such as intuitions ,  and emotions ,  are required.
According to Damasio and coworkers , in situations of uncertainty or complexity, emotional responses may provide valuable information about the potential consequences of a behavioral option, and enable faster and experience-driven decision making by steering attention towards the outcomes to which a given action may lead.
To illustrate, it has been demonstrated that people with deficits in brain areas involved in the processing of emotions (ventromedial prefrontal cortex) perform worse on complex decision-making tasks. 
Relying on one’s gut feeling, as normal people without emotion processing deficits typically do, thus may favor rather than compromise decisions with uncertain long-term benefits.  From these findings, it can be inferred that hot states are crucial in promoting advantageous decision making in contexts that do not allow for explicit deliberation about the long-term consequences of these decisions.
Thus far, direct experimental evidence for the notion that hot states may support advantageous decisions with uncertain outcomes is lacking.
Studies examining the straightforward benefits of hot states – rather than the disadvantages of not being able to use one’s emotions in complex decision making – are lacking. Moreover, there are no studies that examine the causal effect of hot states on complex decision making in normal samples, precluding conclusions about the assumed advantages of hot states in uncertain conditions.
Findings from a correlational study in a non-clinical sample, however, lend initial support to our counterintuitive hypothesis, showing that stock investors who experienced more intense feelings achieved a better decision-making performance. 
In the present study, we explore the notion that people who have an inclination to act on impulse because of being in a hot state, are capable of decisions that increase their maximum benefit when complex decisions with uncertain outcomes are involved.
Specifically, we examine the novel idea that the hot state of being hungry may leave people to rely more on their gut feeling and that this does not necessarily lead to bad decisions but may rather foster advantageous decision making when these decisions are too complex to explicitly deliberate upon their consequences.
While there is until now no direct evidence suggesting that people in hot states may benefit from their impulsive inclinations, this idea aligns well with recent literature challenging the sharp distinction that has been made in dual systems theories of self-regulation between cool and hot systems. 
Whereas traditionally it is assumed that the cool system is responsible for ‘good’ behaviors and the hot system produces ‘bad’ behaviors, it is now acknowledged that sometimes impulsive states can generate adaptive behavior as well.  These new insights provide a reason to explore the idea that hot states may benefit rather than harm decision making.
We observed no significant differences between conditions in terms of age, F(1, 44) = 2.88, p = .10, gender, BMI, or BIS, all Fs <1, or BAS, F(1, 44) = 1.27, p = .27, indicating that randomization was successful.
An ANOVA with condition as the independent variable and hunger as the dependent variable was conducted to test the validity of the hunger manipulation, yielding a significant effect, F(1, 44) = 53.68, p<.001, pη 2 = .55. As expected, participants in the hot (hunger) condition reported more hunger (M = 3.08, SD = .90) than those in the cool (sated) condition (M = .96, SD = 1.07).
Before conducting the main analyses, we examined correlations of the dependent variables with the BIS/BAS scales. These correlations were not significant (all r’s <.25, p’s >.09). These scales were therefore not included as a covariate. BMI was not significantly correlated with performance on the delay discounting task (r’s <.24, p’s >.10), and therefore not considered as a covariate. Non-parametric tests of the effect of condition on the skewed dependent variable k revealed a significant effect on k large (p<.05), but not on k medium or k small (p’s >.25). Participants in the hot (hunger) condition reported lower discounting rates for large monetary rewards (Md = .004, SD = .015) than participants in the cool (sated) condition (Md = .010, SD = .013), showing that participants in a hot state were better able to appreciate big rewards that they needed to wait for.
Analysis of risk taking
To examine risk taking, an ANOVA with condition as the independent variable and BART performance as the dependent variable revealed no significant effect, F <1, demonstrating that participants in the hot (hungry) condition did not take more risks in pursuing a reward than participants in the cool (sated) condition.
Analysis of reward value
To examine reward perception, size perceptions of objects were analyzed with a repeated measures ANOVA with size perceptions of object type (cookies vs. coins vs. circle) as a within-subjects factor and condition (hot vs. cool as a between-subjects factor. Two participants who reported size estimates of coins (N = 1) or circles (N = 1) >3 SDs from the mean were excluded from the analysis. The analysis revealed a marginally significant main effect of condition, F(1, 32) = 3.98, p = .055, pη 2 = .11, with participants in the hot condition perceiving objects as bigger (M = 9.05, SD = 3.50) than those in the cool condition (M = 6.96, SD = 2.58). Significant effects for object type or the interaction between condition and object type were absent, Fs <1.
These results demonstrate that a hot state (hunger) did affect size perception of food, money and a neutral object to the same extent, although this effect was only marginally significant. Objects were in general estimated as bigger under conditions of hunger than under sated conditions, showing that (reward) perception is increased in a hot state while ruling out the alternative explanation that participants in the hunger condition were simply more interested in food rewards and less interested in monetary rewards compared to sated participants because of being hungry (Table 3).
Study 3 provided further evidence that the hot state of hunger promoted rather than compromised complex decisions with uncertain outcomes that are advantageous in the long run as hungry participants were better able to resist (hypothetical) choices that brought immediate big (but not medium or small) rewards but were ultimately disadvantageous.
Hunger did not affect BART performance, demonstrating that hungry people do not take more risk to jeopardize an amount of money to win a larger amount.
Importantly, similar risk taking tendencies across both conditions were observed despite the perception of increased rewarding value of food and money in the hot condition, thus showing that the hot state of hunger increases motivation to get a reward but not at all prices.
Similar size perceptions of food and monetary rewards also ruled out the alternative explanation that hungry participants did not care for money because of being more interested in food.
Contrary to our expectations, the hot state of hunger also resulted in greater size estimations of a neutral object, challenging the notion that size perception relates to objects with a rewarding value only.
More information:Psychonomic Bulletin & Review (2019). DOI: 10.3758/s13423-019-01655-0
Journal information: Psychonomic Bulletin & Review
Provided by University of Dundee