Hunger is assumed to motivate eating, which satisfies the caloric needs underlying the motivation. However, hunger’s influence extends beyond food consumption to the acquisition of nonfood items that cannot satisfy the underlying need (e.g., binder clips), suggesting that domain-specific motives can influence behavior in unrelated domains that are irrelevant to the motive. This is likely to occur when the domain-specific response includes concepts and behaviors that can also guide decisions in other domains. 
 
 Abstract 
 
 Hunger motivates people to consume food, for which finding and acquiring food is a prerequisite. We test whether the acquisition component spills over to nonfood objects: Are hungry people more likely to acquire objects that cannot satisfy their hunger? Five laboratory and field studies show that hunger increases the accessibility of acquisition-related concepts and the intention to acquire not only food but also nonfood objects. Moreover, people act on this intention and acquire more nonfood objects (e.g., binder clips) when they are hungry, both when these items are freely available and when they must be paid for. However, hunger does not influence how much they like nonfood objects. We conclude that a basic biologically based motivation can affect substantively unrelated behaviors that cannot satisfy the motivation. This presumably occurs because hunger renders acquisition-related concepts and behaviors more accessible, which influences decisions in situations to which they can be applied. ||||| Shopping when hungry could be a bad idea (Image: UpperCut Images/Getty) 
 
 Shopping on an empty stomach? Go and eat something quick! People buy far more stuff and spend more money when they're hungry than when they're full, and that extends to non-edible goods, too, according to a study of the association between our bellies and our belongings. 
 
 One day in 2007, Alison Jing Xu, who studies decision-making at the University of Minnesota, Minneapolis, sat down at a mall restaurant and suddenly regretted everything she had just bought. "I wondered why half an hour ago it had seemed like a good idea to buy 10 pairs of tights, not just the two I needed," she says. 
 
 "As a researcher interested in human behaviour, I wanted to understand this. We already know that when we are hungry in a supermarket, we buy more food – I wondered whether hunger might have also increased my desire to purchase non-food items." 
 
 To find out, she and her colleagues conducted five different experiments. 
 
 In one experiment, 77 volunteers going in or out of a cafe were asked to rate how hungry they were, and then asked to rate a set of 10 items for how likeable they were and a different set for their desire to have them. 
 
 The sets always included a variety of five food items such as a sandwich or a cookie, and five non-food items such as a wireless mouse or a spa visit. On average, hunger had increased how much the participants liked food items and had no effect on non-food items, but it significantly increased their desire to acquire both food and non-food items. 
 
 Gimme those clips! 
 
 In another experiment, 63 people came to the lab with an empty stomach. Half were then fed some cake. All the volunteers were asked to examine a binder clip and decide how many they would like to try out. They were also asked how much they liked the clips and how hungry they were from one to 10. 
 
 Once again, hunger had no effect on how much people liked the clips. However, hungry participants – who had an average score of 7.72 on the hunger scale – asked to take away 70 per cent more free clips than those who had just eaten and had an average rating of 2.91 on the hunger scale. 
 
 To find out if the same association held true for real purchases, the team hung around outside a large department store that mainly carried non-food goods. 
 
 They asked 81 customers leaving the store whether they could have a peek at their receipt. They also asked them to rate their hunger and their mood, and to say how long they had been in the store. Customers who were hungry – whose hunger score was above the median score for the whole group - spent 64 per cent more money than those who were less hungry – even when the team allowed for mood and time spent shopping. 
 
 Spill-over effect 
 
 So what's going on? When we are hungry, our stomach releases a hormone called ghrelin. This acts on an area of the brain called the ventromedial prefrontal cortex, which is involved in reward and motivation, making people want to seek out and consume calories. 
 
 Jing Xu suggests that ghrelin's effect also spills over into non-food domains – prompting you to acquire more of everything when you are hungry. "We'd like to make consumers aware of the possibility that if they go shopping on an empty stomach, they might spend more money that they intend to – so better feed themselves before they go out," she says. 
 
 She adds: "We're now going to look at how hunger might influence other behaviours, like how people communicate with others." 
 
 Journal reference: PNAS, DOI: 10.1073/pnas.1417712112 
 
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– You probably know that walking into a grocery store on an empty stomach is unwise. Now a new study suggests walking into a mall while hungry is just as bad—at least for your wallet. The study's title sums up the finding: "Hunger promotes acquisition of nonfood objects." Reporting in the journal PNAS, researchers at the University of Minnesota say they conducted five experiments whose results consistently showed an increase in the desire to acquire things when people reported being hungry. In one experiment where the items (in this case, binder clips) were free, the hungry cohort left with 70% more than satiated participants. And even when people had to pay (this time for department store items), the hungry ones spent 64% more. "It's probably better to feed yourself before any type of shopping, whether you're going on an actual shopping trip or shopping online," researcher Alison Jing Xu tells Smithsonian. "And if you're really hungry, you'd better think twice before purchasing any items at all or you might regret those purchases later." (The study notes that "hunger does not influence how much they like nonfood objects.") New Scientist reports Xu was inspired by a shopping trip of her own, during which she bought 10 pairs of tights on an empty stomach, "not just the two I needed." She says ghrelin, a hormone released by the stomach that makes people seek out food, may also affect other behaviors. (Doctors are puzzled by a boy who's never hungry.)