Hesitating between a piece of fruit and a cake – who has never been faced with this kind of situation? However, we don’t all react in the same way; some of us resist immediate gratification, while others tend to give in more easily. A team of researchers explains why.

Economic theory states that we attribute a value to each of the options that are presented to us in order to choose one of those options. In neuroscience, studies suggest that the regions of the brain involved in forming memories, such as the hippocampus, are involved in thinking up new situations. The team of Mathias Pessiglione (Brain and Spinal Cord Institute, France - ICM) started out with the following hypothesis: the hippocampus might play a critical role in assessing imagined outcomes – in other words, it plays a role in our ability to resist temptation. Typically, this concerns intertemporal choices, which means choosing between an immediate modest reward and a big reward in the future. Previous studies have already shown that people who know how to wait have greater activity in the dorsolateral region of the prefrontal cortex, an area involved in controlling behavior.
Here, the idea was to change the way in which various options were represented to show them via either a perception system or via a mental simulation system.

Twenty people volunteered to choose between immediate concrete rewards (food, or a cultural or sporting activity), in the form of a photograph, and abstract rewards at a time in the future, in the form of text. Brain activity in the subjects was recorded using a functional MRI while they were replying to questions such as: “Would you prefer a packet of crisps now or a dinner on a Parisian boat in a month?”

The results show that at the time of making the decision, the people who opted to wait for their reward had a higher level of activity in their hippocampus. To take this further, the researchers decided to include in their study people suffering from Alzheimer’s disease, because it is known that the hippocampus becomes atrophied in these patients. The results for these patients indeed show that they tend to prefer immediate rewards. According to researchers, this behavior could explain why they find it hard to imagine future rewards, because of the deterioration of their hippocampus.

The effort involved in imagination in order to think about a future reward would be a source of motivation that might explain why we are able to resist temptation.