Imagining bodily states, like feeling full, can affect our future preferences and behaviour

Our current bodily states influence our preferences and our behaviour much more than we usually anticipate – as anyone who has gone shopping hungry and come back with bags full of fattening food can attest. "Even when people have previous experience with a powerful visceral state, like pain, they show surprisingly little ability to vividly recall the state or to predict how it affects someone (including themselves) when they are not experiencing it," writes Janina Steinmertz at Utrecht University and her colleagues in their paper in Personality and Social Psychology Bulletin.

The good news is their research suggests we can exploit this phenomenon – we can trick ourselves into thinking we're feeling differently, thereby influencing our preferences in ways that help us. For instance, one potentially important finding from their paper was that people who thought themselves full went on to choose smaller food portion sizes.

The research builds on earlier work that's found that getting people to consider a particular experience can have a similar effect as actually doing it. For example, people who looked at pictures of salty, savoury foods and rated how much they'd enjoy them, subsequently enjoyed eating peanuts less than others who'd first looked at images of sweet foods. It's as if merely considering salty food had led to a degree of satiation.

Steinmertz and her colleagues wanted to investigate whether mentally simulating feeling warm or cold, and also hungry or full, affected people's subsequent preferences, and even their actual behaviour.

For the first study, 119 participants spent 30 seconds imagining themselves in a picture that either depicted a very cold environment (a snowy landscape or a picture of a glacier) or a hot environment (a desert or a lava lake). Afterwards, people in the cold condition reported feeling colder and were more likely to say they preferred "warming" activities, like a hot bath, to cooling activities, like a "cool, refreshing shower".

A similar effect occurs based purely on our imagination, without the aid of pictures. For the second study, 300 participants were spent 60 seconds imagining, in detail, feeling very hot – or cold, hungry, or full. They then wrote about how they thought they would feel, and how they would act. This kind of purely mental simulation also influenced their reported preferences for related activities – people who'd imagined being hungry were more likely to say they'd prefer to go on a date to a restaurant than a date to see a movie, for example.

To find out if we can exploit these effects to our advantage, the researchers recruited another 111 people to explore the effects of imagining bodily states on subsequent food choices. Participants spent a minute imagining either being hungry or full. Then they were asked to choose between a variety of rewards, including varying sizes of popcorn, chocolate ice cream and crisps, one of which they were told they would receive. Crucially, the participants who'd imagined being full chose smaller food portion sizes than those who'd imagined being hungry. This showed, the researchers write, that mentally simulating visceral states "can affect real choices with immediate consequences".