Attentional bias modification for acute experimental pain: A randomized controlled trial of retraining early versus later attention on pain severity, threshold and tolerance

Background: Noxious attentional bias is thought to confer vulnerability to pain, suggesting that modifying the bias could reduce pain outcomes. Herein is presented a randomized controlled trial to test the effects of retraining the dot probe attentional bias at short versus long stimulus durations towards neutral stimuli, and away from threat stimuli, on acute pain experience, in comparison with a placebo control group. Methods: Eighty-one pain-free volunteers, blinded to condition, were randomized to complete either one of two neutral bias modification programs in which words were presented for 500 ms (ABM-500; n = 28) or 1250 ms (ABM-1250; n = 26), or to a sham training program that included both stimulus durations (ABM-Placebo; n = 27). Testing took place in a university laboratory. At post-training, participants completed the pain-inducing `cold pressor task', and measures of pain severity, threshold and tolerance were taken. Attentional bias was also measured at pre-and post-training. Results: Findings indicated that ABM-500 reliably increased pain threshold and tolerance, in comparison with the control group. In contrast, ABM-1250 did not affect any of the pain outcomes. Expected ABM effects on attentional bias were not evident at the group level, but nevertheless ABM-500 bias reduction was significantly associated with increased pain tolerance. Conclusions: These findings suggest that retraining attention at short stimulus exposure durations is relatively more efficacious in promoting transfer of attentional retraining effects to real-world acute pain stressors, in comparison with both the longer stimulus duration and ABM-Placebo. Significance: Testing of the impact of modifying maintained attentional bias on vulnerability to an acute pain stressor. Findings suggested that retraining rapid attentional bias using short exposure durations conferred greater analgesic benefit, in comparison with both the slower bias and sham-training.