Computerized anxiety sensitivity treatment (CAST), which has been used by researchers already in many RCTs. This involves 30 minutes of psychoeducational video material delivered via computer presentation followed by 30 minutes of repeated interoceptive exposure practice exercises such as 60 seconds of breathing through a coffee straw, shaking head from side to side, and looking into a mirror.

Developed as a 30-minute online intervention that provides education about physical health habits that can impact mental health, such as diet, exercise, and sleep. This intervention has been used in prior clinical trials to control for effects of general education, general coping techniques, and use of technology. Participants in past clinical trials have reported that HET is engaging and beneficial.

CAST is a transdiagnostic cognitive behavioral therapy (CBT)-based protocol designed to address elevated AS, particularly the amplification of cognitive stress symptoms including perceived confusion and memory problems. CAST is a fully computerized, 1-hour intervention. CAST contains video animation and audio narration throughout, as well as interactive features (e.g., brief quizzes to promote comprehension). Procedures draw heavily on standard CBT techniques; AS, a core vulnerability for anxiety and depression is targeted using these procedures. In this study, participants complete CAST as a group alongside other participants.

18 item self-report measure indexing anxiety sensitivity (Taylor et al., 2007). Scores range from 0-72 with higher scores indicating more severe anxiety sensitivity

8-item self-report measure indexing overall anxiety (Pilkonis et al., 2011). Scores range from 8 to 40 with higher scores reflecting worse anxiety symptoms.

8 item self-report measure indexing depressive symptoms (Polkonis et al., 2014). Scores range from 8-40 with higher scores reflecting worse depression symptoms.

7-item self-report measure used in prior studies (Short et al., 2017). Scores range from 0-21 with higher scores indicating more favorable acceptability ratings.

Participants were given two items assessing how frequently they: 1) thought about CAST content in the past month; 2) engaged in interoceptive exposure practice.

12 item self-report measure indexing intolerance of uncertainty (Carleton et al., 2007). Scores range from 12-60 with higher scores reflecting worse intolerance of uncertainty.

Self-report measure assessing how close group members felt with other members of their group (adapted from Byrne et al., 1971)

Brief measure of numerical ability (Cokely et al., 2011) with scores ranging from 0-4, higher scores indicate better numerical ability.