Brain-to-brain Synchronization Represents Interpersonal Interaction And Its Gender Difference During Spontaneous Lie

Deception is defined as a psychological process by which an individual deliberately attempts to convince another to accept as true what the first individual knows to be false to gain benefits or to avoid losses.Usually,the other in the interaction will detect the lie for the sake of interests.However,previous researches mostly examined the brain activity of the liar or the detector separately.Very little paid attention to the intrinsic nature of the lying behavior in the interactive condition from brain-to-brain viewpoint.Otherwise,we know little about the brain activity related to the success of lying,as well as the role nonverbal interactive behavior played.Present study discussed the problem above and explored lying in real time interaction from brain-to-brain perspective.In Study 1,female college students were made pairs respectively.Each pair was asked to complete a spontaneous lying task in the sender(liar)-receiver(detector)paradigm.To investigate the role nonverbal cues played in lying behavior,the face-toface and face-blocked condition(i.e.a clapboard between two subjects)were set up.Meanwhile,a hyperscanning study was conducted by using functional near-infrared spectroscopy to record the brain activity of two participants' dorsolateral prefrontal cortex(DLPFC)and right temporal parietal junction(rTPJ)simultaneously.This study attempts to figure out the brain-to-brain mechanism behind lying behavior by analyzing the relation between interpersonal neural synchronization(INS)and the behavior in the task.The behavioral results showed that(i)there was no significant difference in the rate of succeed in lying between the face-to-face and face-blocked interaction,however,compared with the face-blocked condition,the receivers in the face-to-face condition used less random guessing,and that(ii)under controlling the sender's Machiavelli score and extraversion score,as well as the receiver's extraversion score and selfrecognition of the ability of lying,the average eye-contact duration between the interactive subjects were positively correlated with the rate of succeed in lying significantly,and there was a marginal significant positive correlation between the average eye-contact frequency and the rate of succeed in lying.The hyperscanning results showed that(i)in the process of face-to-face interaction,there was INS in DLPFC between the female pairs,while INS was significantly decreased in faceblocked interaction lacking in nonverbal clues;and that(ii)only in face-to-face condition,was there a significant positive correlation between INS and the rate of succeed in lying,moreover,INS played as a mediator in the relation between eye contact and the rate of succeed in lying.To sum up,the results indicated that nonverbal cues(especially eye-contact)played an important role in interacting with strangers.In addition,many previous studies found that there was gender difference in lying behavior,but they paid little attention to the brain-to-brain mechanisms behind more detailed lying behavior(e.g.the strategies of lying,successful lying).Therefore,Study 2 recruited male participants additionally based on Study 1 to go deeply into the brainto-brain mechanism of lying behavior and its gender differencesThe behavioral results showed that i)both boys and girls were more likely to adopt simple lie strategies rather than sophisticated lie;and that ii)boys told sophisticated lies more frequently than girls in face-to-face conditions,while the strategy that girls and boys adopted had no significant difference in face-blocked conditions.The hyperscanning results showed that(i)in the process of face-to-face interaction,there was INS in rTPJ between the male pairs,while INS was significantly decreased in face-blocked interaction lacking in nonverbal clues;and that(ii)for female pairs,INS between the sender's rSMG and receiver's DLPFC was much higher in the face-to-face condition than that in the face-blocked condition.Moreover,INS above was significantly positive correlated with the sender's simple lie rate during the faceto-face interaction rather than face-blocked interaction.For males,INS between the sender's DLPFC and the receiver's pre-and supplementary motor cortex increased in face-to-face condition.Besides,there was a significant positive correlation between the INS above and the sender's sophisticated lie rate in face-to-face interaction rather than face-blocked interaction.From the perspective of brain-to-brain,the present study revealed that nonverbal cues(especially eye-contact)played an important role in the process of strategic interaction with strangers,and that gender could moderate the effect of interaction condition on lying,which was reflecting both on behavior and on brain-to-brain mechanism.When successful lying or using lie strategies,girls and boys depended on different psychological processes.