Prolonged Social Isolation is Associated with Increased Behavioural Sensitivity to ‘Likes’ on Social Media

Short-term isolation studies indicate that social isolation increases sensitivity to social rewards, yet ethical constraints limit the translation of this finding to prolonged isolation in humans. To address this, we investigated social reward processing during prolonged isolation by modelling Twitter activity during COVID-19, when online spaces substituted for in-person contact. By fitting computational models to US Twitter users (n=535 and n=553,945 tweets), we found that social media posting was driven by both reinforcement learning (receiving more ‘likes’ decreased time between posts) and habitual processes (time between posts was influenced by previous behaviour). During prolonged social isolation, users were more sensitive to social media social rewards: ‘likes’ more strongly influenced the decision to post more or less frequently. These findings provide the first large-scale study of social reward processing during prolonged isolation, using ecologically valid data and more representative samples to translate principles of social reward processing into human prolonged isolation.