右侧颞顶联合区及道德加工脑网络的功能连接预测社会性框架效应:来自静息态功能磁共振的证据

Functional connectivities of the right temporoparietal junction and moral network predict social framing effect:Evidence from resting-state fMRI

社会性框架效应指个体进行社会性决策时,描述方式(即框架)对其选择倾向的影响。采用“伤害/帮助框架”范式,本研究在行为上发现了显著的框架效应:被试在伤害框架下比帮助框架下,更倾向于选择利他选项,这可能是由于伤害框架凸显了伤害他人的后果及有意性,从而提高了道德冲突水平。在神经活动上发现(1)静息态下,右侧颞顶联合区(TPJ)的低频振荡振幅(ALFF)与框架效应强度存在显著正相关;(2)道德加工相关脑区构成的局部脑网络内部的功能连接强度(FC)能够有效预测框架效应强度。本研究首次利用静息态功能连接探讨个体的社会性决策受到语言表述方式影响的神经机制,为进一步揭示社会决策中的个体差异提供了神经学证据。

As an important cognitive bias,the framing effect shows that individuals'decision preferences are sensitive to the verbal description(i.e.,frame)of options.The social framing effect could be distinguished from the non-social one according to whether the decision would influence others.The psychological mechanisms of the non-social framing effect(e.g.,Gain/Loss framing effect)and that of the social one are essentially different.When making non-social decisions,frames affect people’s judgment of which option is more beneficial or less risky.When making social decisions,frames affect people’s preferences through the influence of other-regarding concerns and social norms.In the present study,a new paradigm was developed to induce the social framing effect.We asked participants to make a tradeoff between economic benefits and the feelings of others;when participants showed a stronger preference for income maximization,the probability for their partners to receive a painful electrical shock would increase proportionally.This decision was described as either a“harm”to,or simply“not helping”other persons in two frame conditions.30 participants(age:20.58±1.91 years old)were enrolled in the experiment and 24 of them were included in the final analysis.The resting-state functional magnetic resonance(rs-fMRI)data was acquired using the Echo Planar Imaging(EPI)sequence from a 3-T Siemens scanner.This scanning acquired 180 volumes with TR=2 s(lasting 6 min).Rs-fMRI data were processed and analyzed using the DPABI and RESTplus toolbox to calculate the amplitude of low-Frequency Fluctuation(ALFF)and Functional Connectivity(FC).On the behavioral level,we found that participants made more prosocial decisions in the Harm frame compared to the Help frame condition,resulting in a significant social framing effect.For the resting fMRI analysis,we first run a whole-brain correlation analysis between ALFF and the behavioral index and found the ALFF of the right temporoparietal junction(rTPJ)could significantly predict the behavioral index of the social framing effect.Considering the observed social framing effect would result from different levels of moral conflict between Harm and Help frames,we predicted that it would be closely related to the moral network.Therefore,we further localized 12 seeds from a new,meta-analysis of functional MRI studies for moral processing.Seed-based FC analysis showed that the functional connectivity between the medial prefrontal cortex and the caudate was significantly associated with the behavioral index of the social framing effect.Multivariate machine learning-based regression analysis further confirmed these results,suggesting the importance of rTPJ and moral network for the observed social framing effect.The present study is based on a novel experimental paradigm,using resting functional imaging techniques to explore the brain mechanism of the social framing effect.We found that the ALFF value of the right TPJ and the strength of the functional connectivity value between the medial prefrontal lobe and the caudate within a moral network can effectively predict the social framing effect.This study is the very first one to explore the extent to which individual social decision-making can be influenced by verbal description and its underlying neural mechanisms,which shed light on the further exploration of individual differences in social decision-making.