Periodic Reporting for period 1 - BETTERCHOICES (Understanding and improving choices: investigating the role of stress-related neuromodulators and psychiatric diagnoses in decision-making and precommitment)
Période du rapport: 2024-01-01 au 2026-06-30
Everyday decisions, such as deciding what to eat or whether to exercise, have a profound effect on our long-term health. For example, diets high in fat and sugar are associated with an increased risk of obesity and type 2 diabetes. Understanding the different factors which influence these everyday choices and testing the effectiveness of strategies aimed at improving decision making are key public health aims.
In this project, we focused on the effect of stress on health-related decision making and how we can make healthier choices under stress. Stress is both costly and highly prevalent with over a quarter of the European workers reporting that their mental wellbeing is affected by stress. The psychological and bodily changes associated with stress can have a detrimental impact on our health-related choices. For example, people often prefer unhealthier food when they are stressed and stress has been linked to higher rates of alcohol consumption and smoking.
We focused on the effectiveness of a self-control strategy called precommitment, which involves restricting one’s future choices or adding extra costs to future choice options which do not align with our long-term goals. For example, a person might avoid buying unhealthy food when grocery shopping, so they are not tempted to eat this food at home. Or we might agree to attend an exercise class with a friend so that there are extra costs involved in not exercising, such as our friend’s disappointment if we cancel the appointment.
Although precommitment has been shown to be effective for various types of decision making, whether it is an effective strategy under stress was not known. Therefore, the key objective of this project was to test whether precommitment can help people make healthier choices when they are stressed. This would provide a scientific basis for interventions aimed at improving decision making and potentially reduce the impact of stress-related disease.
In this project, we focused on the effect of stress on health-related decision making and how we can make healthier choices under stress. Stress is both costly and highly prevalent with over a quarter of the European workers reporting that their mental wellbeing is affected by stress. The psychological and bodily changes associated with stress can have a detrimental impact on our health-related choices. For example, people often prefer unhealthier food when they are stressed and stress has been linked to higher rates of alcohol consumption and smoking.
We focused on the effectiveness of a self-control strategy called precommitment, which involves restricting one’s future choices or adding extra costs to future choice options which do not align with our long-term goals. For example, a person might avoid buying unhealthy food when grocery shopping, so they are not tempted to eat this food at home. Or we might agree to attend an exercise class with a friend so that there are extra costs involved in not exercising, such as our friend’s disappointment if we cancel the appointment.
Although precommitment has been shown to be effective for various types of decision making, whether it is an effective strategy under stress was not known. Therefore, the key objective of this project was to test whether precommitment can help people make healthier choices when they are stressed. This would provide a scientific basis for interventions aimed at improving decision making and potentially reduce the impact of stress-related disease.
We developed a novel experimental procedure called the ‘precommit-to-eat’ paradigm to test how stress impacts precommitment. Participants, who reported trying to eat healthily in their everyday lives, came to the lab twice: once when they were placed under acute stress and once when they were in a non-stressful control condition. In each session, they completed two tasks in which they made choices about pairs of food items. In each pair, one food item had been rated as tastier but less healthy (e.g. chocolate muffin) than the other item (e.g. banana).
In the first task, participants were presented with the pairs of food items. For half of the pairs (viewing trials), participants simply observed the food items. However, for the other half of pairs (precommitment trials), participants could remove the tastier but unhealthier food item (e.g. the chocolate muffin) from their future choice, thereby limiting their later options (e.g. only the banana remained available). The number of unhealthier items participants removed indicated the extent of precommitment – that is, how much they restricted their future choice set.
In the second task, participants chose which food items they would like to eat at the end of the experiment from the same food pairs they had seen in the first task. If participants had removed the unhealthier item in the first task, then they were compelled to select the healthier item in this pair in the second task. This allowed a direct comparison between choices made with and without the opportunity for prior precommitment. We also collected salivary cortisol and measures of participants’ psychological stress throughout the experiment to assess stress responses.
We found that the opportunity to precommit – the chance to remove the unhealthier food items – increased the selection of healthier food items by over 40%. When participants felt more stressed, they were more likely to pick the unhealthier food items to eat in the second task, but only when they had not previously had the chance to precommit. When given the chance to precommit in the first task, participants who felt stressed made healthier choices in the second task at the same rate as those who did not feel stressed. Further analysis showed that increased feelings of stress were associated with more precommitment in the first task.
This shows that when behavioural strategies, such as precommitment, are available, stress can prompt greater use of these strategies. The results show that precommitment is an effective self-control strategy for maintaining healthier choices under stress.
In the first task, participants were presented with the pairs of food items. For half of the pairs (viewing trials), participants simply observed the food items. However, for the other half of pairs (precommitment trials), participants could remove the tastier but unhealthier food item (e.g. the chocolate muffin) from their future choice, thereby limiting their later options (e.g. only the banana remained available). The number of unhealthier items participants removed indicated the extent of precommitment – that is, how much they restricted their future choice set.
In the second task, participants chose which food items they would like to eat at the end of the experiment from the same food pairs they had seen in the first task. If participants had removed the unhealthier item in the first task, then they were compelled to select the healthier item in this pair in the second task. This allowed a direct comparison between choices made with and without the opportunity for prior precommitment. We also collected salivary cortisol and measures of participants’ psychological stress throughout the experiment to assess stress responses.
We found that the opportunity to precommit – the chance to remove the unhealthier food items – increased the selection of healthier food items by over 40%. When participants felt more stressed, they were more likely to pick the unhealthier food items to eat in the second task, but only when they had not previously had the chance to precommit. When given the chance to precommit in the first task, participants who felt stressed made healthier choices in the second task at the same rate as those who did not feel stressed. Further analysis showed that increased feelings of stress were associated with more precommitment in the first task.
This shows that when behavioural strategies, such as precommitment, are available, stress can prompt greater use of these strategies. The results show that precommitment is an effective self-control strategy for maintaining healthier choices under stress.
The project has advanced our understanding of how stress impacts health-related decision-making. Whilst previous work has highlighted the benefits of precommitment in a range of contexts, we have provided the first experimental evidence demonstrating the effectiveness of this behavioural strategy under stress. Our key finding that precommitment can prevent the detrimental effect of stress on unhealthier food choices has major implications beyond the state of the art.
Firstly, stress and altered decision making are major contributors to unhealthy lifestyles in clinical disorders, such as obesity and depression. This project provides a platform on which to test precommitment interventions in clinical populations, who are known to experience heightened stress and make fewer healthy everyday choices.
Secondly, our newly developed ‘precommit-to-eat’ paradigm quantifies the extent to which people use and benefit from precommitment. This is currently being used in a neuroimaging experiment to investigate the neurocognitive mechanisms underlying decision-making under stress.
Thirdly, these findings could be extended to domains beyond food choices. For example, engaging in exercise, adhering to medication, and consuming alcohol are all health-related behaviours which are impacted by stress. These domains are all exciting avenues for future work.
Together, this will provide us with deeper insights into the links between stress, cognition, and self-control, and potentially highlight the conditions under which precommitment is most effective.
Firstly, stress and altered decision making are major contributors to unhealthy lifestyles in clinical disorders, such as obesity and depression. This project provides a platform on which to test precommitment interventions in clinical populations, who are known to experience heightened stress and make fewer healthy everyday choices.
Secondly, our newly developed ‘precommit-to-eat’ paradigm quantifies the extent to which people use and benefit from precommitment. This is currently being used in a neuroimaging experiment to investigate the neurocognitive mechanisms underlying decision-making under stress.
Thirdly, these findings could be extended to domains beyond food choices. For example, engaging in exercise, adhering to medication, and consuming alcohol are all health-related behaviours which are impacted by stress. These domains are all exciting avenues for future work.
Together, this will provide us with deeper insights into the links between stress, cognition, and self-control, and potentially highlight the conditions under which precommitment is most effective.