Experimental Investigation of Non-Verbal Communication in Eating Disorders.

This study aimed to be the first to measure non-verbal communication in 25 eating disorder (ED) and 25 non-ED control participants during a naturalistic social interaction incorporating positive, negative and neutrally-valenced topics. The first hypothesis, that ED participants would show significantly reduced facial emotional expression than controls, was not supported. Supporting the second hypothesis of between-group differences in non-verbal behaviour, ED participants were less likely to lean in towards their interlocutor (d=.81) discussing negatively-valanced topics and were more likely to be positioned upright when discussing positively-valenced topics (d=.1.09) than controls. Irrespective of emotional valence, ED participants positioned their gaze on their interlocutor significantly less (d=.29) and spent more time looking down (d=.54), or away than controls (d=.63). ED participants moved their hands along with speech significantly less (d=.63) and gestured fewer real/hypothetical/imagined images/actions/objects) than controls (d=.57), irrespective of emotional valence. Instead, ED participants indicated discomfort in the social interaction, touching their nose (d=.89) or playing with their nails (d=.95) more often than controls. ED participants, regardless of emotional valence, showed significantly lowered electro-dermal activity (d=.60) than controls, supporting the exploratory hypothesis. People with EDs appear to make less efficient use of non-verbal communication than controls.