Scalable, Low-Cost Augmented Reality Mobile Treatment for Spider Phobia: A Randomized Controlled Trial (Preprint)

BACKGROUND Background: The global gap between demand for and access to evidence-based psychological treatment is large and accelarating. Smartphone-based augmented reality may help reduce this gap by improving accessbility to exposure-based therapies and reducing cost. OBJECTIVE Objective: This study evaluated the effectiveness and user engagement of a fully automated smartphone-based augmented reality treatment for spider phobia symptoms. METHODS Methods: We conducted a single-blind randomized controlled trial to evaluate the effectiveness of a fully automated smartphone-based AR cognitive behavioural therapy (CBT) app for spider phobia. A total of 113 adults (ages 18-65) with spider phobia symptoms were randomized to either the 6-week AR-CBT intervention (n = 56) or a wait-list control group (n = 57). All participants completed assessments remotely at baseline, post-intervention (6 weeks), and 3- and 12-month follow-ups. The intervention guided users through graded AR-based exposure to spiders via their own smartphone without therapist involvement. The primary outcome was change in spider phobia symptoms, measured by the Fear of Spiders Questionnaire. Secondary outcomes included anxiety, depression, app engagement, and in-app fear/disgust ratings. Analyses followed the intention-to-treat principle and were preregistered. RESULTS Results: The intervention group showed significantly greater spider phobia reductions at post-test compared to controls (d = 1.25; 95% CI, 0.77–1.73; P< .001). Effects were maintained at 3-month- (d = 1.69) and 12-month follow-up (d = 1.64). Number needed to treat was 2.1. Longer session duration predicted greater improvement; practice session count did not. Overall dropout was 21%. CONCLUSIONS Conclusions: This study is the first to demonstrate that a fully automated mobile AR-CBT intervention, delivered in real-world settings without therapist involvement, can lead to strong and sustained reductions in spider phobia symptoms. By leveraging everyday smartphones and cutting-edge mobile AR technology, this intervention offers a low-threshold, widely accessible, scalable alternative for treating specific phobias. CLINICALTRIAL Prospectively Registered, Overview of Medical Research in the Netherlands, NL70238.029.19 (TrialNL9221) (https://onderzoekmetmensen.nl/nl/trial/27993).