The effects of noxious heat, auditory stimulation, a cognitive task, and time on task on pain perception and performance accuracy in healthy volunteers: A new experimental model

The effects of cognitive and competing sensory processing tasks on pain perception and as a function of time are only partially understood. To study these effects, we compared the simultaneous effects of noxious heat stimulation (HS), auditory stimulation (AS) (sinusoidally modulated speech-like signal, SMSLS), and a cognitive task (CT) (rate change detection of the SMSLS) on pain perception and task performance over repeated experimental runs. Sixty healthy paid volunteers were randomly assigned to four groups, one exposed to AS while performing the CT, one to HS (46 degrees C/6 min), one to AS and HS, and one to AS and HS while performing the CT. Each group performed the experimental run four times, each run for 6 min. Immediately after each run, the subjects rated pain intensity using a VAS (0-100). Two-way RM-ANOVA for analyzing pain intensities among the three heat pain groups demonstrated significant differences of VAS ratings (F-2,F-179 = 4.57, P=0.019), being highest in the HS group (55 +/- 0.7SEM), followed by the AS + HS (39 +/- 6.8) and AS + HS + CT (33 +/- 0.7) groups. Post-hoc analyses revealed that group HS differed significantly from group AS + HS + CT and from group AS + HS (P < 0.05, SNK), whereas group AS + HS did not differ significantly from group AS + HS + CT. Neither pain rating, nor rate of errors on the CT varied significantly across runs. These findings point to a significant influence of competing passive sensory processing on pain perception, with the cognitive task not necessarily adding to the perception of pain. Advantages and shortcomings of the present experimental model for future pain studies are discussed. (c) 2005 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.