Exploring a Potential Facilitating Role for Pain-Related Attentional Bias in Nocebo Hyperalgesia

Abstract

The nocebo effect comprises the negative counterpart of the placebo. This occurs when administration of an inert intervention, coupled with negative information or conditioning, results in the occurrence of negative effects. While the literature agrees on the importance of negative expectancies in activating nocebo effects, other potential factors remain relatively overlooked. The aim of the present study was to use a novel gaze-augmented dot-probe task to investigate whether pain-related attentional bias contributes to nocebo effects. This was founded on theories within the pain literature, which propose a causal role for attentional biases in the subsequent experience of pain. Ninety-three participants (60 female, M = 19.67) were randomly allocated to one of four groups (nocebo-towards, nocebo-away, control-towards, control-away). A gaze-augmented variant of the the dot-probe training task was designed in an attempt to manipulate attentional biases either towards or away from pain. Participants then received either nocebo or control instruction and conditioning, by pairing a sham TENS device with contingently high pain stimulation (nocebo) or non-contingent pairing (control). Participants were required to rate pain intensity, expectancy and distress during a test phase where all TENS and no-TENS shocks were administered at the same intensity. Results showed an overall nocebo effect – rating TENS paired shocks higher than no-TENS – for all outcomes. No consistent training effect was shown for attentional bias across reaction time and eye-tracking measures. However, attentional bias was shown to interact with nocebo conditioning for intensity ratings, with tentative partial support shown for expectancy. The key interaction showed attentional bias condition to differentially affect nocebo extinction trends. Thus, results provide preliminary validation for exploration of attentional bias as a potential mechanism of nocebo hyperalgesia, however necessarily a more sensitive and dependable measure of attentional bias must be established to allow more definitive conclusions.