The rest of it, apparently too long for the forum, had to cut up into two posts.
We are all prone to negative thoughts about the world, but that we can regulate them – until hunger breaks down our ability to do so
It discovered that the judges were more lenient at the start of the day and just after lunch, when they were full, than just before lunch or at the end of the day. While this study has been criticised – the effect could have resulted from other factors, such as how the cases were scheduled, rather than the judges' hunger levels – science does support the notion that we become more punitive when we haven't eaten.
According to Lindquist, it's hard to determine the cause of effects found in studies conducted in real world situations, such as during parole board hearings – there are always alternative, possible explanations. But you can often control for these under laboratory conditions.
To test whether people really were harsher towards others when hungry, then, Lindquist invited 236 people into her lab. About half had fasted for at least five hours while the other half had eaten beforehand. They were then asked to perform a tedious task rotating geometric shapes on a computer before it suddenly crashed (or so they thought) – forcing them to start over and do it all again.
At the end of this frustrating exercise, the participants were given the opportunity to review the researcher – and potentially deliver a little passive aggressive retribution.
"People who were hungry, especially those who weren't paying attention to their emotions or focused on their internal state, were more likely to rate the researcher as judgmental [a negative verdict the researchers took to be punitive] on a little rating sheet we provided," says Lindquist.
The exact reasons why hunger makes us feel and behave in this way are complex. It could be down to an impairment in self-control that arises when blood glucose levels are depleted by fasting. This theory seems to suggest that we are all prone to negative thoughts about the world, but that we can regulate them – until hunger breaks down our ability to do so.
The feelings that are generated in your body when hungry turn up the dial on what you are experiencing – Kristen Lindquist
The view has been criticised, however, and other theories are becoming increasingly popular. Lindquist, for example, believes that feelings such as "hanger" are really just a misinterpretation of a physiological state as an emotional one. This is supported by Lindquist's finding that hungry people who don't reflect on their emotions are more likely to misinterpret them and end up more angry and punitive as a result.
"The feelings that are generated in your body when hungry turn up the dial on what you are experiencing in that context," explains Lindquist. "So maybe you normally wouldn't be irritated at all by a slight from your co-worker, but when you're hungry you think it was a horrible thing to say."
This idea might be a game changer for people on diets. If the negative mental aspects of feeling hungry are caused by us misinterpreting a physical sensation, we could perhaps learn to reinterpret that physical sensation in a better way. This could work in a similar way to cognitive behavioural therapy (CBT), helping us to reframe our thoughts and feelings.
Jonker's study on the emotions of hungry women appears to back this up – she found that women with symptoms of eating disorders experienced more positive feelings when hungry than women without such symptoms. Although eating disorders are complex mental health conditions, the findings suggest these women had relearned the "normal" association of hunger as a negative experience.
Jonker's study on the emotions of hungry women appears to back this up – she found that women displaying some of the symptoms of eating disorders experienced more positive feelings when hungry than other women. Although eating disorders are complex mental health conditions, the findings suggest these women had relearned the "normal" association of hunger as a negative experience. While such mental reframing is highly counterproductive and dangerous when you're battling an eating disorder, Jonker is looking at ways it can be used in more positive ways.
There are evolutionary reasons why we might misinterpret hunger as something deeply unpleasant. After all, when we're running low on nutrients, our brains need us to act rather than sit around contentedly with our feet up.
"From an evolutionary standpoint, it makes sense that hunger would be accompanied by the impulse to go out and forage for things – to maybe prioritise immediate gains as opposed to long-term gains," adds Lindquist.
Food restriction also affects cognition more directly
Indeed, a study from the University of Dundee in the UK showed that people do become increasingly biased towards the present when they are hungry – and struggle to delay gratification.
The researchers offered study participants an immediate reward of either £20 cash or 20 song downloads – or double that amount in the future. If the participants weren't hungry, they were willing patiently to wait for 90 or 20 days, respectively, for the bigger reward. But among the hungry participants, these numbers shrank to 40 and 12 days, respectively. And that makes sense if the hunger signal is intended to spur us into action now, rather than plan for a more distant future.
Food restriction also affects cognition more directly. A 2021 review of the research investigating the effects of fasting on cognition found that attention and cognitive flexibility, the ability to switch between different tasks, are particularly affected.
Most of us will know what it feels like to have our attention hijacked by persistent thoughts of gooey chocolate cake, hot, crisp chips, or spicy noodles when we're hungry. And research has shown this is very common – hunger increases our attention to cues related to food. Again, this is also in keeping with the idea that the point of the physiological feeling of hunger is to make us go out and get food – and that shifting our attention away from whatever else we're doing is the first stage of this process.
In the modern world, and particularly in the West, it is rarely difficult to obtain food though. So being distracted by hunger isn't that useful anymore. It can create more disadvantages than advantages.
Jan Rummel, a cognitive psychologist at the University of Heidelberg in Germany and colleagues tested whether being hungry makes people more prone to intrusive mind-wandering, such as fantasising about food.
"Usually, if you find people mind-wandering, the performance in a task they are doing goes down," he explains, adding that this effect only applies when the task is sufficiently complex, such as reading. "If we are ironing or something, then I think we can have our minds wander and it doesn't affect the task performance because the task is simple enough."
Researchers discovered that the more people's minds were wandering, the worst they performed on the task
He set out to test the extent to which famished people are affected by mind wandering in a complex task – reading 27 pages of the epic novel War and Peace followed by a reading comprehension test. They were also asked whether their minds were wandering and, if so, what they were thinking about. In the test, 39 people were asked to show up to the laboratory without eating for five hours, while 91 were told to arrive satiated. Among the latter group, 46 people got to listen to a recording of an erotic story to see if that increased mind wandering.
