Processing of subliminal facial expressions of emotion: a behavioral and fMRI study

The recognition of emotional facial expressions is an important means to adjust behavior in social interactions. As facial expressions widely differ in their duration and degree of expressiveness, they often manifest with short and transient expressions below the level of awareness. In this combined behavioral and fMRI study, we aimed at examining whether or not consciously accessible (subliminal) emotional facial expressions influence empathic judgments and which brain activations are related to it. We hypothesized that subliminal facial expressions of emotions masked with neutral expressions of the same faces induce an empathic processing similar to consciously accessible (supraliminal) facial expressions. Our behavioral data in 23 healthy subjects showed that subliminal emotional facial expressions of 40 ms duration affect the judgments of the subsequent neutral facial expressions. In the fMRI study in 12 healthy subjects it was found that both, supra- and subliminal emotional facial expressions shared a widespread network of brain areas including the fusiform gyrus, the temporo-parietal junction, and the inferior, dorsolateral, and medial frontal cortex. Compared with subliminal facial expressions, supraliminal facial expressions led to a greater activation of left occipital and fusiform face areas. We conclude that masked subliminal emotional information is suited to trigger processing in brain areas which have been implicated in empathy and, thereby in social encounters.