Neurophysiological correlates of interpersonal discrepancy and social adjustment in an interactive decision-making task in dyads

Abstract

Introduction: The pursuit of convergence and the social behavioral adjustment of conformity are fundamental cooperative behaviors that help people adjust their mental frameworks to reach a common goal. However, while social psychology has extensively studied conformity by its influence context, there is still plenty to investigate about the neural cognitive mechanisms involved in this behavior.

Methods: We proposed a paradigm with two phases, a pre-activation phase to enhance cooperative tendencies and, later, a social decision-making phase in which dyads had to make a perceptual estimation in three consecutive trials and could converge in their decisions without an explicit request or reward to do so. In Study 1, 80 participants were divided in two conditions. In one condition participants did the pre-activation phase alone, while in the other condition the two participants did it with their partners and could interact freely. In Study 2, we registered the electroencephalographical (EEG) activity of 36 participants in the social decision-making phase.

Results: Study 1 showed behavioral evidence of higher spontaneous convergence in participants who interacted in the pre-activation phase. Event related Potentials (ERP) recorded in Study 2 revealed signal differences in response divergence in different time intervals. Time-frequency analysis showed theta, alpha, and beta evidence related to cognitive control, attention, and reward processing associated with social convergence.

Discussion: Current results support the spontaneous convergence of behavior in dyads, with increased behavioral adjustment in those participants who have previously cooperated. In addition, neurophysiological components were associated with discrepancy levels between participants, and supported the validity of the experimental paradigm to study spontaneous social behavioral adaptation in experimental settings.

Keywords: EEG; ERPs; adjustment; dyadic decision-making; social cognition.

Figure 1

(A) Disposition of the lab for the different group configurations in Study 1. Left: Cooperative dyad setting; Middle: Individual dyad setting; Right: during the task. Note that in Study 2, all participants were in the Cooperative setting. (B) Design of the task. The trial started with its number, and then a red point appeared on a line between two numbers. Participants had to enter the estimation of the position of the point using individual keypads, and after the two participants had pressed the intro key, the estimation of the two participants appeared on the screen (FB1). Then the same sequence with the same figure was presented two more times, and participants received the information about their and their peers’ estimation (FB2 and FB3). After that, the new trial started. The figure also explains what “discrepancy” and “adjustment” mean in our experiment.

Figure 2

Divergence in responses at every feedback repetition. First plot shows data from Study 1, and also compares between groups. Second plot shows the same tendency in data from Study 2.

Figure 3

Plots that depict the differences in responses to questions by Group: (A) “Did you like the experiment?,” (B) “Did you feel synched with your partner?,” (C) “Did you find you could trust your partner?” and (D) “Did you find rewarding working with your partner?

Figure 4

(A) ERPs at the central electrodes (Fz, Cz, Pz) for every feedback and the identification of the different ranges of interest over signals (225–275 ms., 275–350 ms., 350–500 ms., 500–700 ms.). (B) Topographies at three feedback conditions through the intervals.

Figure 5

Density plots showing minimum, maximum and differences in signal from the posterior data ( $P\left(D|\theta \right)$ ) at maximum Discrepancy in 1st feedback. Shadowed area in the differences plot represents the empirical ROPE. Dimmed white lines inside the posterior density represent three percentiles (0.025, 0.5, 0.975).

Figure 6

Time-frequency plots depicting the three feedback power changes per electrode and the difference between the 1st and the 3rd feedback power.