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Degree of smiling (AU 12) (mean values (+SD) while undergoing non-painful and painful heat stimulation (study 1)). Values are given separately for the group of subjects being seated in sight of the experimenter (visual interaction) and for the group unobserved by the experimenter (nonvisual interaction). (Moderate (d > 0.5) and strong (d > 0.8) effect sizes between stimulus intensities are marked in bold.)
