SC Connecticut News

Yale researchers have discovered that hearing an unexpected sound just before making a decision can lead individuals to make riskier choices. The study, published on September 13 in Nature Communications, highlights how external auditory stimuli may influence decision-making processes and could offer insights into dopamine systems in the brain, potentially contributing to understanding conditions like schizophrenia and depression.

Robb Rutledge, an assistant professor of psychology at Yale’s Faculty of Arts and Sciences and senior author of the study, explained: “Many of us might have the intuition that hearing an unexpected sound would be distracting, that it might lead to errors or a loss of focus. But when we think about the neurobiology, we know that dopamine plays a role in decision-making and a surprising sound leads to a short burst of dopamine.” Rutledge added that these sounds might signal something important or rewarding, thereby affecting decision-making by altering dopamine levels.

Rutledge and Gloria Feng, a Ph.D. student in Rutledge’s lab and lead author of the study, hypothesized that surprising sounds unrelated to a decision could still influence it due to shared dopamine activity. To test this theory, they conducted seven experiments involving 1,600 participants who were asked to choose between safe and risky options with varying point values. Participants heard sequences of tones before making their choices; some sequences included an unexpected tone.

“We found that surprising sensory events, these unexpected sequences of tones, increased people’s risk-taking,” said Feng. Participants chose the risky option 4% more often after hearing rare sequences compared to common ones. They were also more likely to switch their choice from the previous trial after hearing rare sequences.

Further experiments revealed that playing both tone sequences equally often eliminated these effects. However, switching the frequency so that uncommon tones became common did not increase risky decisions but still led participants to change their previous choices more frequently.

“These two effects are separable,” noted Feng. “There could be something different about the underlying neurobiology driving them.”

Rutledge emphasized the consistency of these findings despite modest increases in risk-taking: “Think about say an urban environment where there are so many sounds that are mostly irrelevant to our daily decisions. Maybe those sounds are affecting decisions even when we don’t notice.” He speculated whether such effects might be prevalent in noisy environments like casinos: “If a slot machine goes off at the right moment, maybe someone at a Blackjack table is 4% more likely to make a riskier choice.”

Beyond immediate decision-making implications, these findings may enhance understanding of dopamine's role in mental illnesses such as schizophrenia and depression. Rutledge remarked on dopamine's involvement in psychosis related to schizophrenia: “Schizophrenia can be enormously damaging... We have some drug treatments for schizophrenia that block dopamine, but we need to do better.” He also highlighted potential applications for depression treatments targeting dopamine.

Feng suggested using sounds as tools for delivering temporary bursts of dopamine in humans could aid research into its effects on decisions: “This tool could help researchers better understand the effects dopamine has on the decisions we make.”

For further information contact Bess Connolly at elizabeth.connolly@yale.edu.

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