How Trait Confidence and Communication Shape Dyadic Decision Outcomes and Confidence Matching

When individuals collaborate, they often rely on momentary estimates of their own and their partner’s confidence (decision confidence) to guide collective decisions and achieve their goals. Through interaction, these confidence estimates tend to align over time. This process is known as confidence matching. More stable, dispositional trait confidence is also emerging as a key factor shaping the dynamics and outcomes of collaborative action. We examined how trait confidence and type of communication impact the accuracy of dyadic decisions, decision confidence, and the dynamics of decision confidence, including confidence matching. In this study, 210 participants completed general knowledge tests individually and collaboratively, forming 105 dyads. The tests were completed under three communication conditions: isolated (no interaction), passive (viewing the partner’s response and numeric confidence rating), and active (verbal discussion). Participants assessed as high-trait or low-trait confidence (controlling for cognitive ability) were allocated to three types of dyads: low-trait (two low-trait members), mixed-trait (one low-trait and one high member), or high-trait (two high-trait members) confidence dyads.Trait confidence moderated decision accuracy and decision confidence gains: dyads with mixed-trait or high-trait confidence showed greater decision accuracy improvements in the active than the passive communication condition compared to their individual decisions. Whereas low-trait confidence dyads benefited equally from active and passive communication. Collaboration increased decision confidence overall, especially for high-trait confidence dyads under active communication. Confidence matching occurred rapidly in both passive and active communication but predicted decision accuracy gains only in the passive condition where participants had limited social information. Although active verbal communication led to the greatest overall decision accuracy, these gains were not driven by confidence matching. Our findings highlight the critical role of trait confidence in shaping collaborative outcomes in dyads and extend previous research by showing that confidence matching occurs naturally during verbal communication.