| The metaphor association that the clean is moral and the dirty is immoral exists in daily life across the Chinese and western culture backgrounds,and the psychological reality of moral purity metaphor had been supported by empirical researches.Embodied cognition theory on metaphor predicted that the processing of moral metaphors is essentially an interactive activity of mapping a concrete source domain with sensorimotor experience to an abstract target domain comprising abstract moral concepts,and then had an influence on moral cognitions and moral judgments.The present study adopted the moral dilemma paradigm to investigate the influence of different types of cleansing priming tasks on moral judgments and neural mechanism in the dynamic process of metaphorical mapping with functional near-infrared spectroscopy(fNIRS)measurement.In the behavioral study,some participants were asked to wash hands after making ethical or unethical behaviors and completed moral judgment tasks,while the rest performed an imagery version by imaging washing their hands under a voice guidance after an ethical or unethical behavior,followed by moral judgment task.Statistical analysis were used to explore the effect of two ways of cleansing on moral judgment.The results revealed a significant interaction between the morality value of participants’ behaviors and types of cleansing tasks.The behavioral results also showed that unethical-behavior participants made harsher moral judgment whether they completed the self-cleansing task or the imagined one,and participants washing their hands before made harsher moral judgment than imaging washing hands whether they making ethical or unethical behaviors.A functional near-infrared spectroscopy device was used to record cortical activation activities during the two cleansing tasks,especially hemoglobin concentration changes in 47 measurement channels,and examined hemodynamic activities in corresponding regions.The fNIRS results reported significant activations in premotor and supplementary motor cortex,dorsolateral prefrontal cortex and the right frontopolar area when ethical-behavior participants were washing their hands,and significant activations in premotor and supplementary motor cortex and the left frontopolar area in the unethical behavior group.In the cleansing imagery condition,unethical behavior group produced significantly greater change in cortical oxygen level in premotor and supplementary motor cortex and the right dorsolateral prefrontal cortex when they were washing their hands.In the washing-hands condition,the results showed a significant difference in the left frontopolar area between unethical and ethical behavior groups.For unethical-behavior group,significant difference were revealed in the right dorsolateral prefrontal cortex between the two types of cleansing tasks.Based on these findings,the current research suggested that the scores of moral judgment may differ in different ways of cleansing priming conditions although they may share the same neural basis of brain,which was affected by information processing style in physical cleansing experience and the morality value of participants’ behaviors.The mapping of moral purity metaphor should be regarded as a result of interactive activity amid several functional brain areas like somatosensory cortex and social cognition system. |
