Efficacy of attention bias modification via smartphones in a large population sample

Negative affective biases are a key feature of anxiety and depression that uphold and promote negative mood. Bias modification aims to reduce these biases using computerized training, but shows mixed success and has not been tested at scale. The aim was to determine whether bias modification delivered via smartphones can improve mood in a large sample. In total, 153 385 self-referring participants were randomly assigned to modification or sham bias training on a dot-probe or visual-search task. The primary outcome of interest was balance of mood, assessed on the Positive and Negative Affect Schedule. In total, 22 933 participants who provided at least two mood ratings were included in analyses. There was a large amount of participant attrition. In the remaining smaller sample, results supported the prediction that visual-search modification would result in improved mood (95%CI [0.10, 0.82]; p = 0.01, d = 0.05, N = 2588 after two ratings; 95%CI [1.75,6.54]; p = 0.001, d = 0.32, N = 118 after six ratings), which was not seen for the sham version (N = 4818 after two ratings; N = 138 after six ratings). Dot-probe modification was not associated with mood improvements (p = 0.52). Visual-search, but not dot-probe, bias modification slightly but significantly improved mood. Although this effect size is very small and subject to large participant drop-off, it might be worth considering an adjunct to current treatments.