Hemispheric effects in facial and emotional perception

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Student Showcase of Research & Engagement Spring 2019
Milligan, Megan
This study investigated the effect of hemispheric field upon the perception of normal and Thatcherized (faces with inverted mouth and eye features) faces. The prevailing evidence is that faces are processed either locally in parts (eyes, nose, mouth) or globally by the relationships between parts. Emotional processing theories include the valence hypothesis (positive emotions processed in left hemisphere, negative in the right), the approach-withdrawal hypothesis (approach emotions processed in the left hemisphere, withdrawal in the right), and the right hemisphere hypothesis (all emotions processed in the right hemisphere) (Adolphs, Jansari, & Tranel, 2001; Quaranta, Siniscalchi, & Vallortigara, 2007; Natale, Gur, & Gur, 1983). Faces were presented on PowerPoint slides at 12 respective angles (0 to 330 degrees rotation) for 0.20 seconds in either the left or right visual field. Normal faces were generally seen as happier than distorted faces, and normal faces differed significantly based on hemisphere and angle (F(11)=2.17, p=.01), as did distorted faces (F(11)=4.55, p=.00) with a Tukey's post hoc revealing significant differences between angles 60 and 300 (F(1)=20.61, p=.00). There was a general trend of misidentifying emotions when the mouth was tilted away from the focal point, indicating that the mouth may be essential in identifying happiness.