Message similarity as a proxy to repetitive thinking: Associations with non-suicidal self-injury and suicidal ideation on social media

Detecting signs of rumination (specifically negative repetitive thinking) in social media data could be beneficial to predicting mental health, as rumination is associated with mental health problems. The objective of this study is to evaluate message similarity as a proxy measure of repetitive thinking (a core component of rumination), using data from Vent — a social media platform dedicated to emotion sharing. Our analyses suggest that automatic assessment of message similarity aligns with human judgements. Furthermore, message similarity is positively associated with signs of suicidal ideation/non-suicidal self-injury, and this association is stronger in users who post predominantly negative content, in line with observations from the literature. This effect has a relatively small magnitude and may be less visible in machine learning models with a large number of predictors. Our data suggests that message similarity may be a useful way of capturing repetitive content, which can potentially be used as a stepping stone to automatic rumination detection in social media data.