无意识的情绪面孔加工及其潜在神经机制

Unconscious processing of emotional faces and its probable neural mechanism

随着探索无意识信息加工实验技术的日渐精湛,越来越多的研究表明,无意识的视觉信息能够对人类的认知和行为产生影响.本文综述了由自下而上的视觉输入强度不足而非注意资源不足而导致的无意识情况下人们对恐惧面孔加工的实验研究.采用视觉掩蔽、双眼竞争、眼间抑制等范式的研究和对脑损伤病人的研究均互为印证发现,一些皮层下结构(如上丘、丘脑和杏仁核)以及它们之间的功能连接对无意识的恐惧面孔加工起到重要作用,从而可以推测人类对情绪面孔(尤其是带有威胁性的恐惧面孔)的加工可能得益于一条绕过初级视觉皮层的皮层下快速通路.但这条通路对无意识恐惧面孔加工的贡献还需要更多来自于揭示因果关系而非相关关系的实验研究的证据,并且这条高效的通路在意识上又会发挥何种作用亦有待于今后的研究考察.

With the advancement of techniques in probing unconscious visual processing, an increasing number of researches have demonstrated that unconscious visual information could have an impact on human being’s cognition and behavior. This review mainly introduces those studies regarding processing of fearful faces which are rendered subconscious through weak bottom-up inputs rather than insufficient top-down attentional resources. Studies that adopted backward masking, binocular rivalry, and interocular suppression paradigms and those conducted on patients who suffered from visual cortex lesion have shown converging evidence that some subcortical structures, like superior colliculus, thalamus, and amygdala, and the functional connectivity between these regions contribute to the unconscious processing of fearful faces. It is thus suggested that the human brain is able to process unconscious emotional faces through a rapid subcortical route bypassing early visual cortex. However, this route still needs further studies to delineate its causal instead of correlational relationship with unconscious processing. In addition, how the highly efficient subcortical route adds to the conscious processing of emotional faces is worthy of future investigations.