Using an ideal observer analysis to investigate the visual perceptual efficiency of individuals with a history of non-suicidal self-injury when identifying emotional expressions

Individuals who engage in non-suicidal self-injury (NSSI) often report significant interpersonal difficulties, with studies lending support to the idea of impaired social interactions. Perceptual processing deficits of facial expressions have also been associated with interpersonal difficulties, yet little research has assessed how individuals with a history of NSSI (HNSSI) process facial emotions. This study used an ideal observer analysis to assess emotion processing capabilities of these individuals. A total of 30 HNSSI and 31 controls were presented with static images of various facial expressions (fear, anger, disgust, happiness, sadness, surprise) at three intensity levels (50%, 75% and 100% emotion expressivity). Recognition of emotions were measured by signal-proportion thresholds, efficiency scores, and unbiased hit rate. Error responses were also recorded to investigate errors biases made by each group. No significant differences between HNSSI and controls were found in signal-proportion thresholds or efficiency scores. Decreased accuracy of HNSSI participants for recognizing fearful expressions was observed. An increased likelihood of mistaking angry for happy expressions and a decreased likelihood of mistaking sad for surprised expressions were recorded for the HNSSI group compared to controls. These findings provide support to the literature reporting deficits in accurate emotion identification for those engaged in NSSI behaviours.