This study examined how the outcomes of joint decision making relate to cardiovascular reactions when group members disagree about the decision to be taken. A conflict was experimentally induced during a joint decision-making task, while cardiovascular markers of challenge/threat motivational states were assessed following the biopsychosocial model of challenge and threat (BPSM; J. Blascovich, ). Results show that individuals were less likely to adjust their initially preferred decision alternative the more they exhibited a cardiovascular pattern indicative of threat (i.e., relatively high total peripheral resistance and low cardiac output) compared to challenge. This finding extends the BPSM by showing a link between threat and rigidity, and emphasizes the importance of psychophysiological processes for studying intragroup conflict and decision making.