Increased Interpersonal Brain Synchronization in Romantic Couples Is Associated with Higher Honesty: An fNIRS Hyperscanning Study

Abstract

Previous studies on the brain-brain interaction of deception have shown different patterns of interpersonal brain synchronization (IBS) between different genders. However, the brain-brain mechanisms in the cross-sex composition need to be better understood. Furthermore, there needs to be more discussion about how relationships (e.g., romantic couples vs. strangers) affect the brain-brain mechanism under interactive deception. To elaborate on these issues, we used the functional near-infrared spectroscopy (fNIRS)-based hyperscanning approach to simultaneously measure interpersonal brain synchronization (IBS) in romantic couples (heterosexual) and cross-sex stranger dyads during the sender-receiver game. The behavioral results found that the deception rate of males was lower than that of females, and romantic couples were deceived less than strangers. Significantly increased IBS was observed in the frontopolar cortex (FPC) and right temporoparietal junction (rTPJ) of the romantic couple group. Moreover, the IBS is negatively correlated with the deception rate. No significantly increased IBS was observed in cross-sex stranger dyads. The result corroborated the lower deception of males and romantic couples in cross-sex interactions. Furthermore, IBS in the PFC and rTPJ was the underlying dual-brain neural basis for supporting honesty in romantic couples.

Keywords: deception; fNIRS hyperscanning; gender composition; romantic love.

Figure 1

Experimental design. (a) Task design. There were four task blocks, each consisting of 12 trials. (b) Trial design. Events and time flow in a trial. (c) Experimental scene. (d) Optode probe set. The optode probes were placed on the prefrontal cortex and the right temporal parietal junction. The Fpz and P6 in the International 10–20 system were used as reference sites.

Figure 2

FDR-corrected p-maps of couple groups. The task-related IBS of the couple group was significantly higher than that in the resting-state session, ranging between 0.086 and 0.192 Hz (period 5–12 s) and between 0.011 and 0.022 Hz (period 44–94 s). Data values above 0.3 Hz were excluded. The red dashed lines represent the frequency band of interest.

Figure 3

Behavioral results. (a) Informer deception rate and (b) guesser winning rate in the four groups. Error bars indicate standard errors. * p < 0.05, ** p < 0.01, *** p < 0.001. ns: no significance.

Figure 4

Task-related IBS. (a) Upper graph: One-sample t-test map of task-related IBS (0.086–0.192 Hz) for the CMF group (false discovery rate (FDR)-corrected). Lower graph: Comparisons of IBS at CH01 (0.086–0.192 Hz) for the CMF group with the other three groups. (b) Upper graph: One-sample t-test map of task-related IBS (0.086–0.192 Hz) for the CFM group (false discovery rate (FDR)-corrected). Lower two graphs: Comparisons of IBS at CH03 and CH08 (0.086–0.192 Hz) for the CMF group with the other three groups. (c) Upper graph: One-sample t-test map of task-related IBS (0.086–0.192 Hz) for the CMF group (false discovery rate (FDR)-corrected). Lower graph: Comparisons of IBS at CH19 (0.011–0.022 Hz) for the CMF group with the other three groups. * p < 0.05, ** p < 0.01.

Figure 5

Correlations between behavioral results and IBS. (a) Pearson’s correlation between IBS at CH03 and the informer’s deception for the CFM group. (b) Pearson’s correlation between IBS at CH19 and the informer’s deception for the CMF group. (c) Pearson’s correlation between IBS at CH03 and the guesser’s winning rate for the CFM group. The gray area indicates the 95% confidence interval.

Figure 6

The mean Granger causalities in two directions. Error bars represent standard errors of the mean. ns: no significance.