Avoidance behaviour performed in the context of a novel, ambiguous movement increases threat and pain-related fear.

The fear-avoidance model of chronic pain predicts that catastrophic (mis)interpretation of pain elicits pain-related fear that in turn may spur avoidance behaviour leading to chronic pain disability. Here we investigated whether performing a movement to avoid a painful stimulus in the context of a novel movement increases threat and pain-related fear towards this novel movement, and whether avoidance behaviour persisted when given the choice between performing the acquired movement to avoid a painful stimulus or an alternative, novel movement. Applying a robotic arm-reaching task, participants could choose between two movements to reach a target location: a short, but painful movement trajectory, or a longer non-painful movement trajectory. After avoidance acquisition, the option to choose the painful trajectory was removed. The Experimental Group (N=50) could choose between the longest trajectory or a novel intermediate trajectory, whereas the Control Group (N=50) was allowed to only perform the novel trajectory. In a final test, participants of both groups were allowed to choose any of the three trajectories. Post-acquisition, Experimental Group participants showed elevated pain-expectancy and pain-related fear towards the novel trajectory, compared to the Control Group. During test, the Experimental Group participants persisted in performing the longest pain-free (avoidance) trajectory, and were less likely to choose the novel trajectory. In addition, these participants maintained higher levels of pain-related fear for the novel trajectory compared to the Control Group. These findings suggest that avoidance in the context of other neutral activities/movements may lead to the development and maintenance of threat appraisals and irrational fears.