‘Fake it Till You Make It’: Investigating the Neural Correlates of Expression Authenticity Perception

Introduction: Human social interactions rely heavily on the ability to assess not just which emotions are expressed, but also whether they are authentic. Genuine expressions are congruent with internal emotional states, whereas posed expressions are intentionally produced for social or strategic purposes. Misjudging emotional authenticity can lead to social misunderstandings and is particularly relevant in psychiatric and neurological conditions. Despite its importance, the neural basis of authenticity perception remains underexplored. This study builds on evidence suggesting that posed and genuine expressions differ in both temporal features and underlying neural pathways and posits that the judgment of authenticity may engage additional brain regions beyond those involved in basic emotion recognition. Methods: Thirty-five healthy adults were recruited for an fMRI study assessing responses to dynamic facial expressions (genuine vs. posed) across three emotions (happiness, fear, disgust), using stimuli validated in a prior behavioral study. During scanning, participants viewed randomized video clips and judged the authenticity of each expression. fMRI data were acquired over three runs on a 3T Philips scanner and preprocessed using standard SPM12 procedures, including normalization and smoothing. A general linear model was applied at the single-subject level, followed by a second-level one-sample t-test comparing genuine and posed conditions across participants. Statistical significance was determined using a cluster-level FWE correction (p < .05, minimum extent = 78 voxels). Behavioral data were analyzed using signal detection metrics and linear mixed-effects modeling. Results: Neuroimaging results revealed significantly greater activation for genuine expressions than posed ones in right-lateralized clusters, specifically within the Superior and Middle Temporal Gyri and the Fusiform Gyrus - regions known to be implicated in face perception, emotion processing, and Theory of Mind (ToM). No significant activation was found for the reverse contrast (posed > genuine). Discussion: The findings suggest that judging emotional authenticity recruits distinct neural processes, with greater activation observed for genuine versus posed expressions in regions associated with social perception and Theory of Mind. These results support the hypothesis that authenticity evaluation is not merely a byproduct of basic emotion recognition but relies on additional inferential mechanisms. The increased cognitive demand reflected in slower reaction times and greater brain activation for genuine expressions underscores the complexity of interpreting subtle, socially significant cues.