A Meta-Analysis of Bias at Baseline in RCTs of Attention Bias Modification : No Evidence for Dot-Probe Bias Towards Threat in Clinical Anxiety and PTSD

Background: Considerable effort and funding have been spent on developing Attention Bias Modification (ABM) as a treatment for anxiety disorders, theorized to exert therapeutic effects through reduction of a tendency to orient attention towards threat. However, meta-analytical evidence that clinical anxiety is characterized by threat-related attention bias is thin. The largest meta-analysis to date included dot-probe data for n=337 clinically anxious individuals. Baseline measures of biased attention obtained in ABM RCTs form an additional body of data that has not previously been meta-analyzed. Method: This paper presents a meta-analysis of threat-related dot-probe bias measured at baseline for 1005 clinically anxious individuals enrolled in 13 ABM RCTs. Results: Random-effects meta-analysis indicated no evidence that the mean bias index (BI) differed from zero (k= 13, n= 1005, mean BI = 1.8 ms, SE = 1.26 ms, p = .144, 95% CI [-0.6 - 4.3]. Additional Bayes factor analyses also supported the point-zero hypothesis (BF10 = .23), whereas interval-based analysis indicated that mean bias in clinical anxiety is unlikely to extend beyond the 0 to 5 ms interval. Discussion: Findings are discussed with respect to strengths (relatively large samples, possible bypassing of publication bias), limitations (lack of control comparison, repurposing data, specificity to dot-probe data), and theoretical and practical context. We suggest that it should no longer be assumed that clinically anxious individuals are characterized by selective attention towards threat. Conclusion: Clinically anxious individuals enrolled in RCTs for Attention Bias Modification are not characterized by threat-related attention bias at baseline