Interspecies research shows that the way decisions are made depends on uncertainty.
Scientists at Dartmoor College have learned how we (and our closest ape relatives) make decisions. College students and a group of monkeys had to complete game tasks, gaining points. Points were converted into money to pay for school (for humans) and delicious juice (for monkeys).
The results of the work, published in the journal Nature Human Behavior, call into question one of the main provisions of the theory of choice. According to existing views, decision-makers use a multiplicative assessment method.
According to research, both humans and primates choose this tactic if both the size of the reward and the likelihood of receiving it are known. If they are forced to make decisions in a situation of uncertainty, then they prefer the additive method.
A risk situation implies that the decision maker has a choice: to risk a higher probability of failure in order to receive a higher value of the reward, or to receive a lower reward with a lower probability of losing. The conditions and degrees of risk, as well as the amount of the reward, are fully known to you in advance.
The situation of uncertainty gives the receiver knowledge based on observation: he is not sure with what probability he can receive a reward, how much the risk of losing increases depending on the increase in the size of this reward. He can observe other players and try to deduce the pattern on his own.
The multiplicative method assumes that the person multiplies the probability function by the reward function. The subjective significance of the difference in the amount of the award or its complete possible non-receipt serves as the basis for making a decision. In a risk situation, most people choose the option with a lower probability of losing, that is, the probability has more weight than the value of the reward.
When the likelihood of receiving a reward is not clear, but the amount of the reward is known, the situation is perceived as more uncertain. Subjects then more often choose more risky options, focusing less on probability and more on the value of the reward. Not being able to assess the probabilities in a balanced way, the subjects tend to seek a large reward, which leads to the choice of an additive way of making a decision.
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The team also examined neural activity in monkey brains during task performance and found a correlation between this behavioral adjustment and how prefrontal neurons present information about reward. For example, neurons in the dorsolateral prefrontal cortex were more active, representing a reward when uncertainty was higher and the reward was more significant in decision making.
“This is the first interspecies study to use such an experimental design to show that both humans and monkeys change strategies when they move from risk-based choices (when the probabilities of reward are known) to uncertainty choices (when the probabilities of reward are unknown and should be studied), from combining information in a multiplicative way to comparing information in an additive way,”notes senior author Alireza Soltani.
The work shows that an overly straightforward understanding of the mechanisms that guide people in a situation of choice leads to errors in predictions. “More broadly, our results show that in the uncertainty of conditions for receiving rewards, which occurs in most cases, we cannot build the so-called subjective value, as prescribed by normative models of choice, and that being flexible is more important than being rational. or optimal,”adds Soltani.
Polina Gershberg
