Exploration-exploitation dilemma in joint value-based decisions is driven by resistance to erratic randomness

Most value-based decisions in everyday human life are made collaboratively, yet research has primarily focused on individuals making private choices. We investigated how face-to-face joint decision-making influences exploration and exploitation in decision-making under uncertainty. To distinguish between seeking new options and prioritizing known rewards, we had participants choose between two virtual slot machines to maximize rewards. Some trials allowed participants to explore and learn about the options iteratively and others only allowed them one choice. This enabled us to distinguish between random, value-free exploration and directed, information-seeking exploration. Comparing individual versus dyadic decision-making we found that dyads outperformed individuals by reducing random exploration, leading to more precise choices and higher long-term gain. However, the extent of directed exploration for information remained similar. These findings suggest that social interaction stabilizes decision-making by curbing erratic choices rather than altering strategic information search.