Brain Follows Crowd in Uncertain Times

Abstract

When making risky choices in social contexts, humans typically combine social information with individual preferences about the options at stake. It remains unknown how such decisions are made when these preferences are inaccessible or disrupted, as might be the case for individuals confronting novel options or experiencing cognitive impairment. Thus, we examined participants with lesions in insular or dorsal anterior cingulate cortex, key regions implicated in risky decision-making, as they played a gambling task where choices were made both alone and after observing others' choices. Participants in both lesion groups showed disrupted use of standard utility-based computations about risky options. For socially situated decisions, these participants showed increased conformity with the choices of others, independent from social utility-based computations. These findings suggest that in social contexts, following others' choices may be a heuristic for decision-making when utility-based risk processing is disrupted.

In uncertain situations where information is lacking, individuals often find themselves imitating the choices of others. For example, if all the customers at a Chinese restaurant are ordering Jajangmyeon (Noodles with Black Bean Sauce), one might also choose Jajangmyeon, even if they prefer Jjamppong (Spicy Seafood Noodle Soup). This behavior highlights a tendency to conform to others when faced with ambiguity. Computational neuroscience research has shown that the decision to follow others unconditionally serves as an alternative strategy that activates certain brain processes in uncertain environments.

A research team, led by Professor Dongil Chung from the Department of Biomedical Engineering at UNIST, along with collaborators from Virginia Tech, investigated how the decisions of others influence individual decision-making in uncertain contexts.

Decision-making in social situations typically involves a value judgment process that integrates both personal preferences and the choices of others. This study uncovers the strategies the brain employs when access to individual preferences is compromised.

According to the research findings, the brain employs a 'heuristic' strategy that reflects social information from the choices of others during decision-making. When value judgments based on individual preferences are not possible, individuals tend to take the shortcut of imitating the decisions made by others.

The research team arrived at these conclusions through experiments conducted on participants with partial damage to the brain's insula or dorsal anterior cingulate cortex (dACC), regions known to play critical roles in processing uncertain information.

In the study, participants engaged in a gambling task where they chose between two options. Each option was associated with a fixed probability of reward-one being a risky choice with a wide range of potential outcomes and the other a safer option with a narrower reward range. Some trials allowed participants to observe the choices made by others before deciding, while other trials required them to make their decisions independently.

Results indicated that participants with brain damage struggled to evaluate options according to their risk preferences. Moreover, the effect of conforming to others' decisions was notably heightened in social situations where participants had the opportunity to observe the choices of others.

The research team noted that the implications of these findings could extend to adolescents, whose individual preferences may be in flux. Both situations of uncertainty and the lack of established personal preferences render value judgments based on individual preferences challenging.

Professor Chung remarked, "This study sheds light on why individuals with unclear personal preferences may be particularly sensitive to the opinions of those around them." He emphasized the importance of creating a supportive environment and implementing educational approaches to help establish individual preferences as a means of addressing social issues such as addiction.

This research was published in PLoS Computational Biology, a journal dedicated to computational analyses in biology on December 2, 2024.

Journal Reference

Mark A. Orloff, Dongil Chung, Xiaosi Gu, et al., "Social conformity is a heuristic when individual risky decision-making is disrupted," PLoS Comput. Biol., (2024).