A novel conversation-analytically informed paradigm was used to examine how joint decision-making interaction, with its various types of proposal sequences, is reflected in the physiological responses of participants. Two types of dyads–dyads with one depressed and one non-depressed participant (N = 15) and dyads with two non-depressed participants (N = 15)–engaged in a series of conversational joint decision-making tasks, during which we measured their skin conductance (SC) responses. We found that the participants’ SC response rates were higher and more synchronized during proposal sequences than elsewhere in the conversation. Furthermore, SC response rates were higher when the participant was in the role of a proposal speaker (vs. a proposal recipient), and making a proposal was associated with higher SC response rates for participants with depression (vs. participants without depression). Moreover, the SC response rates in the proposal speaker were higher when the recipient accepted (vs. not accepted) the proposal. We interpret this finding with reference to accepting responses suggesting a commitment to future action, for which the proposal speaker may feel specifically responsible for. A better understanding of the physiological underpinnings of joint decision-making interaction may help improve democratic practices in contexts where certain individuals experience challenges in this regard.

We used a novel interdisciplinary experimental paradigm where two types of dyads—15 dyads with one depressed and one non-depressed participant and 15 dyads with two non-depressed participants—engaged in a series of food-decision-making tasks. We examined how different communicative events during the decision-making process were reflected in the affective responses of the interacting participants, as indicated in their skin conductance (SC) response rates. The participants’ SC response rates were found to be higher during the emergence of the final decision, compared to the other segments during the process. Furthermore, relinquishing one’s initially expressed preferences was associated with SC response rates higher than the baseline. However, during the relinquishment segments, there was a negative interaction between depression diagnosis and SC response rates, which suggests that, compared to their non-depressed comparisons, it is affectively less arousing for the participants with depression to give up their previously expressed preferences.

Dyads with a depressed and a non-depressed participant (N = 15) and two non-depressed participants (N = 15) discussed a moral dilemma, during which the participants’ gaze direction and skin conductance (SC) were measured. Partner gazing occurred most frequently when a speaker took a strong stance toward saving a person in the dilemma, depressed participants however looking at their co-participants less often than non-depressed participants. The participants’ SC response rates were higher during responsive utterances expressing disagreement (vs. agreement) with co-participant ideas or suggesting that a person be sacrificed (vs. saved). We argue that a better understanding of the affective corollaries of human social interaction necessitates a balanced consideration of both contents of talk and behavioral patterns.