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Katie Gray, Freya Lygo, Miaomiao Yu, Daniel Baker; A common factor may underlie personality traits and both neural and perceptual responses to emotional faces. Journal of Vision 2016;16(12):75. doi: 10.1167/16.12.75.
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© 2017 Association for Research in Vision and Ophthalmology.
Difficulties in interpreting emotional faces are often linked with autistic traits and alexithymia. Yet it is unclear whether these problems are due to reduced neural processing of faces, or differences in decision strategies in perception experiments. To measure neural responses, we adapted a steady-state EEG paradigm (Liu-Shuang, Norcia & Rossion, 2014, Neuropsychologia, 52:57-72) for emotion detection. Random identity neutral faces were presented periodically (at 5Hz) with 'oddball' targets appearing every fifth cycle (at 1Hz). The targets were emotional faces of six emotions (angry, happy, sad, fear, disgust, surprise), morphed along a continuum relative to neutral (0, 6, 12, 24, 48, 96 and 144% emotional intensity). Lateralised occipito-parietal responses at harmonics of the oddball frequency (2, 3 & 4Hz) increased monotonically with morph level for 24 observers, and showed substantial individual variability that was unrelated to the baseline response at the flicker frequency. Observers also completed a 2IFC experiment using the same temporal parameters as the EEG experiment. Observers were presented with a target stream containing a single emotional face embedded within 8 neutral distractors, and a null stream containing only neutral faces, and asked to indicate which stream contained the emotional target. Accuracy increased as a function of morph level, and 75% correct thresholds were estimated from the psychometric functions. Inverting the faces significantly reduced detection performance and EEG responses. We also measured autism quotients and alexithymia using standard scales, and found a typical level of correlation between these measures (r=0.61, p< 0.01). Alexithymia correlated with psychophysical thresholds (r=0.49, p< 0.05), whereas autistic traits correlated negatively with maximum EEG amplitudes (r=-0.50, p< 0.05). Principal components analysis of all four variables identified a single factor with high loadings for each measure. These results suggest that personality differences are predictive of both neural responses to, and perceptual experience of, emotional expression.
Meeting abstract presented at VSS 2016
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