All participants are assigned to the e-couch social anxiety program. Over a 5-week study period, participants are instructed to complete specific modules on a weekly schedule. They are asked to engage with the program at least once per week for approximately 30 minutes. Participants receive weekly reminders and guidance indicating which modules to complete each week.

Participants will be offered the use of a self-help tool, e-couch (https://ecouch.com.au), for 5 weeks. e-couch is an online, self-directed tool that provides interactive self-help and evidence-based information to help users understand and manage common mental health challenges including symptoms of depression and anxiety. The e-couch social anxiety program will be used in this study. It is structured like an interactive self-help book and participants can log back into at any time to learn and review skills. The e-couch social anxiety program includes a comprehensive information module, as well as self-help modules with interactive exercises and workbooks that teach evidence-based strategies. The content will cover topics such as cognitive restructuring and exposure, with an emphasis on learning strategies to reduce social anxiety.

Social anxiety symptom severity will be assessed using the Liebowitz Social Anxiety Scale (LSAS), a validated self-report questionnaire measuring fear and avoidance across social interaction and performance situations. The LSAS total score ranges from 0 to 144, with higher scores indicating greater social anxiety symptom severity.

LSAS total scores will be collected at baseline (pre-intervention) and at the end of the 5-week e-couch intervention period. The outcome metric is the individual-level change in LSAS total score, calculated as the end-of-intervention score minus the baseline score.

The primary outcome is the accuracy with which pre-intervention self-report measures and computerized behavioral task performance predict change in LSAS total score. Analyses will examine the extent to which individual differences in decision-making and cognitive task performance account for variability in symptom change across participants.