The role of low spatial frequencies in facial emotion processing: A study on anorthoscopic perception

We examined the interaction among emotions, spatial frequencies (SF) and holistic analysis using an anorthoscopic paradigm, which is supposed to alter the holistic processing. Emotional and neutral faces were presented sliding behind a narrow aperture (anorthoscopy), or statically in the centre of the screen (whole-face presentation) as broadband images (Experiment 1), filtered at low-SF (Experiment 2), and "hybrids" (emotional low-SF superimposed to neutral high-SF of the same face; Experiment 3). Participants were required to evaluate how "friendly" each stimulus appeared (an indirect measure of emotion processing). These manipulations were aimed at investigating holistic accounts of emotional faces. Friendliness judgments decreased when low-SF and hybrid faces were presented anorthoscopically, possibly due to the impoverished presentation, in which a part-based analysis prevails on a global-based analysis. Although anorthoscopy does not prevent emotion processing, it alters holistic processing of emotional stimuli, confirming the complex interaction among emotions, SF and stimulus presentation.