NO EFFECT OF INVERSION ON PERCEIVED SIMILARITY OF FACIAL EXPRESSIONS OF EMOTION
We studied discrimination of briefly presented upright vs. inverted emotional facial expressions (FEs), hypothesising that inversion would disrupt holistic FE processing and hence decoding emotions. Stimuli were photographs of seven emotion prototypes, of a male and female poser (Ekman & Friesen, 1976), and eight intermediate morphs. Subjects made Same/Different judgements on pairs of upright or inverted FEs, presented for 500 ms. %Same judgements were taken as an index of pairwise perceptual similarity and analysed with multidimensional scaling. The outcome was a 4D â€˜emotion expression spaceâ€™, with Happyâ€“ Sad, Surprise/Fear, Disgust and Anger dimensions. Inverting FEs caused minor changes in the structure or dimensional salience, but solutions for the two posers differed substantially more. The findings imply that briefly presented FEs are processed as patterns of lightness and texture. However, upright and inverted FEs with elements of Happiness were processed categorically, indicating that mouth curvature â€“ conveying Happiness â€“ is processed very early.