We aim to understand how two sources of social influences modulate participants’ risk preferences. We used the Balloon Analogue Risk Task (BART), which is one of the few risk tasks that has reliably predicted participants’ risk behavior in a wide variety of decision domains, to decompose social modulation of risk preferences into contexts shaped by beliefs about the likely behaviors of others, and from direct interaction.
Participants in the BART pump a balloon to accumulate tokens and aim to cash in these tokens before the balloon pops. In social contexts, two participants, each with their own balloon, play simultaneously and besides not popping their own balloons, should cash in higher than their opponent to secure their cashed tokens. In the belief only context, the identity of the opponent was known, but actions during play were hidden. In the interaction only context, opponent identity was hidden, but balloon pump actions were visible in real-time. To measure participants’ beliefs about balloons’ pop point and their opponents’ behavior, we introduced a novel belief elicitation task. In groups of 5-12 we collected data from a total of 159 participants stemming from 29 experimental sessions. In each experimental session, one participant underwent fMRI while playing the BART alone and in social contexts, in real-time, against other session participants who were seated outside the scanner.
Participants’ behavior was substantially influenced by social contexts. In the belief only context participants increase their willingness to take on risk (compared to playing alone) by pumping the balloon an average an additional 6 times. In the interaction only context, participants decrease the average number of pumps (2.5 less). However, the average interaction-only behavior does not tell the complete story. Participants show a preference for pumping to a similar level as their opponent, pumping less when the opponent ends at a lower number and more when the opponent pumps higher. FMRI analyses provide support for separate neural mechanisms underlying social belief and direct interaction. Although both contexts activate theory of mind regions, the belief only context shows a more pronounced activity pattern in frontal medial regions, whereas the interaction only context activates lateral components of brain areas associated with social processing.
In sum, participants’ risk preferences are influenced by social contexts, demonstrating social modulation of risk preferences that can both increase and decrease tolerance for risk as compared to behavior alone. These behavioral differences are supported by separable neural mechanisms which together provide clues for how social factors influence risk preferences in social situations. Furthermore, we replicate findings that behavior in the BART correlates with substance use, indicating the relevance of our task on understanding behavior outside the laboratory.