Double-Blind Acupuncture Needle: A Potential Tool to Investigate the Nature of Pain and Pleasure

Figure 2

Pain intensity for the penetrating needles with a pleasant sensation and with an unpleasant sensation. There was no significant difference between the penetrating needles with the pleasant sensation and those with the unpleasant sensation in the subjects who had pain associated with needle insertion. Pain intensity was expressed on 100 mm visual analogue scale. The top, middle, and bottom lines of the boxes correspond to the 75th, 50th, and 25th percentiles, respectively. The whiskers extend from 10th to the 90th percentile. The circles indicate the arithmetic mean.