ONGOING ISCHEMIC PAIN AS A WORKLOAD INDEXED BY P3 AMPLITUDE AND LATENCY IN REAL-VERSUS FEIGNED-PAIN CONDITIONS

We tested four independent groups: real pain, real pain/tracking, feigned pain, and feigned pain/tracking. After baseline (auditory oddball task only, .8/.2), the real pain groups had an ischemia cuff applied, which generated intense pain after 14 min. The pain feigners were instructed to simulate pain. The oddball task was repeated during low pain (6 min following cuff application) and during high pain (7-15 min following application). Real pain ratings were affected by low versus high pain and by tracking (reporting pain regularly), which elevated ratings. Nontracking feigned- and real-pain subjects differed in oddball-evoked P3 amplitude and latency during high pain. Oddball P3 amplitude decreased and latency increased from real low pain to high pain. Tracked but not untracked real low pain affected oddball P3 amplitude. Real and feigned pain-tracking subjects did not differ in P3 amplitude. P3 latency differed between real-pain and feigning subjects during low-pain tracking. A 91% individual hit rate (real vs. feign) obtained.