Data from University College London's 'The Great Brain Experiment' reveals that we are more likely to make risky decisions later in the day.
05 June 2023
By Emma Young
All kinds of everyday decisions carry some sort of risk. However, we don’t approach potential losses and gains in the same way. With gains, in general, we’re more likely to pick a 100% chance of getting a small reward over a smaller chance of getting a larger reward. With losses, though, if the alternative is a certain small loss, we’re inclined to gamble and risk losing even more.
These distinct risk preferences are thought to be influenced by dopamine and serotonin, neuromodulators whose levels vary throughout the day. This begs the question: might risk-related decision-making fluctuate during the day, too? In a new paper in Scientific Reports, investigations by Rachel L. Bedder and colleagues find that risk-taking in relation to potential losses — though not gains — may indeed be more likely later in the day.
The team analysed data from a risky decision task (presented as a game) that participants completed via an app on their phones, as part of The Great Brain Experiment run by University College London. Each participant started out with 500 points and completed 30 trials. On each trial, they could choose between taking the ‘safe’ option — a guaranteed specified points change — or the ‘risky’ option, which gave them a 50/50 chance of two potential outcomes.
The trials came in three types. On ‘gain trials’, the safe option was a specified points boost, while the gamble would give them either even more points, or none. On ‘loss’ trials, the safe choice was a specified points loss; opting to gamble led to either a bigger loss of points or no points being deducted. In mixed trials, the choice was between no change to their points, or a gamble with a potential loss and a potential gain.
The participants also indicated their age, country and gender, and their responses were time-stamped, so the researchers knew when they had been made.
For their first main analysis, Bedder and her colleagues looked at data from 2,599 participants who had completed the task at least twice on different days. Half of this group had played their second game earlier on in the day than their first (so the order in which participants had played their games was balanced).
The analysis showed that time of day didn’t affect participants’ decisions in the gain or mixed trials. However, on average, they chose more risky options with potential losses later in the day than earlier in the day. Neither age nor gender affected this result. Given the results from all three types of trial, the team concluded that a reduced sensitivity to increasing losses over the day underpinned this result.
For their second main analysis, the team looked at data from 26,720 people who had completed the task via the app at least once, so they could compare the decisions of different individuals. They found the same time of day effect on loss, but not gain, trials. And again, participant age made no difference. However, this time, for the women — but not the men — there was also a time of day effect on risky decisions in the mixed trials. This effect might not have been found for participants who had played the game twice simply because that group was too small for it to become apparent, the team suggests.
Other studies have found sex differences in risk-taking, but little is known about how sex hormones may interact with the circadian rhythms of neuromodulators, including serotonin (which has been linked to decision-making that relates primarily to losses) and dopamine (which has been linked to sensitivity to loss), the team notes.
Though levels of both serotonin and dopamine are known to vary at different points in the day, more work will be needed to fully establish whether changing levels link to variations in risk-taking behaviour.
For now, though, the team’s findings do suggest that people make different decisions later on in the day. The effect sizes reported were small, but there could be real world consequences of this phenomenon, the researchers argue.
For example, perhaps doctors making decisions at night would be more likely to go for riskier, more potentially harmful procedures than they would if making the same decision in the morning. The time of day effect may also influence decisions made by investors on the stock market, for instance. These new findings have “potential importance for real-life decisions that include voting, medical decisions, and financial investments,” the team believes, making this a potentially important topic for future investigation.
Read the paper in full: https://doi.org/10.1038/s41598-023-31738-x
SOURCE:
https://www.bps.org.uk/research-digest/daredevils-dusk-risk-taking-increases-day-draws(accessed 7.6.23)
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