Facial expression megamix: Tests of dimensional and category accounts of emotion recognition

Abstract

We report four experiments investigating the perception of photographic quality continua of interpolated ('morphed') facial expressions derived from prototypes of the 6 emotions in the Ekman and Friesen (1976) series (happiness, surprise, fear, sadness, disgust and anger). In Experiment 1, morphed images made from all possible pairwise combinations of expressions were presented in random order; subjects identified these as belonging to distinct expression categories corresponding to the prototypes at each end of the relevant continuum. This result was replicated in Experiment 2, which also included morphs made from a prototype with a neutral expression, and allowed 'neutral' as a response category. These findings are inconsistent with the view that facial expressions are recognised by locating them along two underlying dimensions, since such a view predicts that at least some transitions between categories should involve neutral regions or identification as a different emotion. Instead, they suggest that facial expressions of basic emotions are recognised by their fit to discrete categories. Experiment 3 used continua involving 6 emotions to demonstrate best discrimination of pairs of stimuli falling across category boundaries; this provides further evidence of categorical perception of facial expressions of emotion. However, in both Experiment 1 and Experiment 2, reaction time data showed that increasing distance from the prototype had a definite cost on ability to identify emotion in the resulting morphed face. Moreover, Experiment 4 showed that subjects had some insight into which emotions were blended to create specific morphed images. Hence, categorical perception effects were found even though subjects were sensitive to physical properties of these morphed facial expressions. We suggest that rapid classification of prototypes and better across boundary discriminability reflect the underlying organisation of human categorisation abilities.

Effects of MDMA and Intranasal Oxytocin on Social and Emotional Processing

“…The first task was the Morphed Facial Expression Task (mFER), which employs standardized faces taken from the Pictures of Facial Affect set (Ekman and Friesen, 1976), morphed by 10% increments between 0% emotional expression (ie, a neutral face) and 100% emotional expression (Young et al, 1997). The version of the task includes four basic emotions (ie, anger, fear, happiness, and sadness).…”

Effects of the 5-HT2C receptor agonist meta-chlorophenylpiperazine on appetite, food intake and emotional processing in healthy volunteers

“…The pictures (from Ekman and Friesen 1976) were morphed from neutral to 100% expressions (Young et al 1997) in 10% stages, producing 10 intensities for each emotion.…”

Morphing between expressions dissociates continuous from categorical representations of facial expression in the human brain

“…These results show that facial expressions that differ in perceived emotion are discriminated more easily than facial expressions that are perceived to convey the same emotion. This finding is widely considered to form the strongest test for behavioral evidence of categorical perception (12).…”

“…Evidence for categorical perception of expression is shown by the consistency with which the basic emotions are recognized (7) and the greater sensitivity to changes in facial expression that alter the perceived emotion (8, 9). In contrast, continuous or dimensional models are better able to explain the systematic confusions that occur when labeling facial expressions (2) and can account for variation in the way that basic emotions are expressed (10) and the fact that we are readily able to perceive differences in intensity of a given emotional expression (11,12).…”