Association between facial expression and PTSD symptoms among young children exposed to the Great East Japan Earthquake: a pilot study

"Emotional numbing" is a symptom of post-traumatic stress disorder (PTSD) characterized by a loss of interest in usually enjoyable activities, feeling detached from others, and an inability to express a full range of emotions. Emotional numbing is usually assessed through self-report, and is particularly difficult to ascertain among young children. We conducted a pilot study to explore the use of facial expression ratings in response to a comedy video clip to assess emotional reactivity among preschool children directly exposed to the Great East Japan Earthquake. This study included 23 child participants. Child PTSD symptoms were measured using a modified version of the Parent's Report of the Child's Reaction to Stress scale. Children were filmed while watching a 2-min video compilation of natural scenes ('baseline video') followed by a 2-min video clip from a television comedy ('comedy video'). Children's facial expressions were processed the using Noldus FaceReader software, which implements the Facial Action Coding System (FACS). We investigated the association between PTSD symptom scores and facial emotion reactivity using linear regression analysis. Children with higher PTSD symptom scores showed a significantly greater proportion of neutral facial expressions, controlling for sex, age, and baseline facial expression (p < 0.05). This pilot study suggests that facial emotion reactivity, measured using facial expression recognition software, has the potential to index emotional numbing in young children. This pilot study adds to the emerging literature on using experimental psychopathology methods to characterize children's reactions to disasters.