Attentional interference, but no attentional bias, by tonic itch and pain stimulation

Introduction: Attentional processes are involved in the experience of itch and pain. They interrupt task performance (ie, attentional interference) or bias allocation of attention toward the somatosensory stimulation, that is, attentional bias (AB). Research on AB toward pain is mostly focused on stimuli with short durations; hampering generalization to tonic pain sensations. Evidence for AB toward itch is lacking so far. This study investigated attentional interference by—and AB toward—experimentally induced tonic itch and pain. Methods: Fifty healthy volunteers performed a somatosensory attention task (SAT), that measured attentional interference and AB during tonic (35 s duration) pain, itch and vibrotactile stimuli. In addition, a dot-probe task measured AB toward visual representations of itch and pain, a Flanker task was used to assess attentional inhibition, and self-reported characteristics were measured. Results: Attentional interference during itch and pain stimuli compared with vibrotactile stimuli was found during the SAT. Exploration of shorter time segments within one tonic stimulus showed slowed responses for all three stimulus types during the first 5 seconds of stimulation. However, no prolonged interference in the following time segments was found. There was no AB toward somatosensory and visual stimuli. Furthermore, there was no association between any of the attentional measures and self-reported characteristics. Discussion: These findings suggest that the beginning of any somatosensory stimulus is interfering with cognitive performance, but the results for prolonged interference by itch and pain are equivocal. There was no indication for biased attention allocation. Whether this pattern is different in patients remains to be investigated in the future.