Physiological Synchrony and Its Impact on Reciprocity in Trust Games

During the experiment, participants wore headphones for audio instructions and did not speak to one another. The trustor in each pair sent between 0 and 6 euros to the trustee, who then had to decide how much of the tripled amount to return. The trustor received no feedback on how much their partner returned, which kept them reliant on live impressions and intuitive judgments. The study used sensors on the participants' fingers and torsos to record skin conductance and heart rate, while webcams filmed their faces to track facial muscle movements. Eye-tracking glasses were also used, but head movements during decisions degraded the recordings, leading to the exclusion of pupil data from the analysis. [1]

The researchers analyzed physiological signals by splitting them into overlapping eight-second windows to measure how closely partners' responses aligned within a four-second lag. They found that sweat synchrony was slightly higher during face-to-face interactions compared to when the barrier was in place, although this difference was smaller than in earlier studies. Additionally, the timing of partners' responses clustered tightly around simultaneous responses during visual contact, while scattering irregularly when the barrier was up. Video recordings indicated that visual contact altered facial behavior, with participants displaying more smiling, friendly expressions, and conversational eyebrow movements when face-to-face, whereas frowning and negative expressions were more common behind the barrier. [1]

The study's findings revealed that trustees returned a larger share of the tripled money when looking at their partner than when separated by the barrier, regardless of which block came first. However, within the face-to-face block, stronger skin conductance synchrony predicted lower reciprocity, meaning trustees returned a smaller proportion of the money when their sweat responses closely tracked their partner’s. This result was unexpected and prompted the researchers to reconsider the function of synchrony beyond its traditional affiliative role. The study also noted that trustors, who made blind choices under uncertainty, had higher overall arousal than trustees, who acted with full information. The negative link between face-to-face synchrony and reciprocity was strongest when the trustor showed low arousal, suggesting that emotional states may play a significant role in how synchrony affects behavior. [1]

The study's authors emphasized that the effects observed were small-to-medium in magnitude, as is typical in laboratory settings where many factors influence behavior and physiology simultaneously. They also cautioned against interpreting the results as a definitive tool for predicting generosity or cooperation, noting that the reversal in reciprocity needs further replication before it can be considered established. The researchers suggested that future studies should allow for conversation, vary feedback, and capture cleaner eye-tracking recordings to better understand when shared bodily rhythms support cooperation and when they undermine it. They also proposed that synchrony may serve as a mechanism for anticipating others' intentions, emotions, and likely actions, potentially enhancing social prediction abilities. [1]

A study published in the Proceedings of the Royal Society B found that physiological synchrony, specifically sweat synchrony, does not always lead to increased cooperation between strangers. The research team measured physiological responses using skin conductance sensors and webcams to track facial expressions. The study also revealed that the negative link between face-to-face synchrony and reciprocity was strongest when the trustor showed low physiological arousal. This finding challenges the assumption that bodily synchrony automatically fosters cooperation and highlights the role of emotional engagement in shaping social interactions (source ID: 1). [1]

The research involved 118 participants, who played an economic trust game under two conditions: face-to-face and with a barrier separating them. Skin conductance synchrony was slightly higher during face-to-face interactions, but this was associated with lower reciprocity from the trustee. The study suggests that mutual visibility strengthens and stabilizes sweat synchrony, but the relationship between synchrony and cooperation depends on the emotional state of the trustor. This adds complexity to the understanding of how physiological synchrony functions in social contexts (source ID: 1). [1]

The researchers found that trustees returned a larger share of the tripled money when looking at their partner than when separated by the barrier, regardless of which block came first. However, within the face-to-face block, stronger skin conductance synchrony predicted lower reciprocity. This unexpected result prompted the team to rethink the function of synchrony, suggesting that it may not always serve as a purely affiliative tool. The study also highlights the need for further research to explore how physiological synchrony influences decision-making in social interactions (source ID: 1). [1]

Sources

PsyPost: Relationships

Prepared with AI assistance from the cited sources.