Attention and pain: are auditory distractors special?

It is well established that manipulations of attention and emotional state can modulate pain. Some researchers have used olfactory or visual distractors to manipulate these factors in combination, and have found that attention and emotion have different effects on pain intensity and unpleasantness. Specifically, distraction from pain was found to markedly reduce its intensity while having little effect on its unpleasantness. Other evidence indicates, however, that the strength of intermodal attentional shifts depends on the specific modalities involved, with auditory-somesthetic shifts being relatively weak. The present study was, therefore, undertaken to determine how pain intensity and unpleasantness are affected when auditory, rather than olfactory or visual, distractors are used. Attention was directed either to the pain from noxious thermal stimuli, or to simultaneously presented environmental sounds that had either positive (e.g., bird chirping) or negative (e.g., alarm clock) associations. To manipulate attention, subjects were instructed to make two-alternative forced-choice discrimination judgments concerning the temperature of the thermal stimuli (in heat blocks) or the loudness of the sound clips (in sound blocks). Unpleasant sound clips were used during half of the heat blocks and half of the sound blocks, with pleasant sounds in the other half. Participants rated two components of pain: intensity and unpleasantness, after each block of trials. Although pain unpleasantness was influenced both by attentional direction and by the valence of the sound clips, pain intensity was not affected by either of these experimental manipulations. The failure of auditory distractors to modulate pain intensity differs from the previously documented ability of olfactory distractors to do so. Our findings are, however, consistent with evidence that one can attend simultaneously to auditory and cutaneous stimuli. Thus, environmental sounds are not effective at reducing pain intensity, but are capable of modulating pain unpleasantness, perhaps because it is constructed at a later stage.