The perception of emotional expressions of varying degrees of definition during the stroboscopic exposure of the face and its masking

This paper examines the role of facial apparent movements in the assessment of basic emotional expressions in favorable and adverse conditions of perception. A previous study has shown that movement could not improve the accuracy of the assessment of emotions in the presence of the detailed information about the configuration of the face. The present investigation aimed at searching conditions in which dynamics provided better assessment of facial expressions. In the psychophysical experiment the modality of expression (6 basic emotions and neutral face), the context, the time of exposure of the face (50, 100, or 200 ms), and the degree of its defocusing (clear or blurry images) varied. The stimulus situation type determined the content of the context: the stroboscopic exposure of expressions against the background of a neutral face or their direct and reverse visual masking by a randomized pattern. The use of a Gaussian filter with pixel values of 20, 40, or 60 provided defocusing. The authors analyzed the data using the method of mixedeffects logistic regression; the frequencies of correct answers in the experimental conditions were compared using linear contrasts. The findings of the study revealed that during stroboscopic exposure the apparent movement ensured the preservation of the accuracy of recognition of basic emotions even in the least favorable conditions of perception (at minimum exposure time and maximum image defocusing). For clear or slightly defocused images the accuracy of assessments when masking and the stroboscopic change of the expression coincided. Masking led to a significant reduction in the accuracy of the assessments of emotions when deteriorating the conditions of perception. The impact of masking was higher when assessing low-attractive emotions (disgust, fear, sadness, and anger); highattractive emotions (joy, surprise, and calm state) were assessed most adequately in all stimulus situations. The obtained effect of stroboscopic sensitization indicated the similarity of the impact of a real and apparent movement on the assessment of emotional states.