Perceived control, locus of control and preparatory information: effects on the perception of an acute pain stimulus

This study investigated the effects of differences in a pre-procedure briefing (providing or withholding preparatory information and explicit control) on the perception of the second of two identical acute pain stimuli. Sixty one healthy participants were allocated to one of three conditions: information + control (I+C), information–no control (I–NC) or no information–no control (NI–NC). Baseline measures of pressure pain threshold (PPT) and pain rating using visual analogue scales (VAS) were taken, as was a measure of general internal/external locus of control (LOC). Participants were read the briefing and subjected to a second pain stimulus of identical intensity to their baseline measures. Participants rated the second stimulus using the VASs, and compared it to the first using comparison scales. Results show that differences in a pre-procedure briefing significantly altered participants’ perception of the pain stimulus. Participants in the I–NC group rated the second stimulus more painful than the first, and participants in the NI–NC group rated the second stimulus as less painful than the first. There is also suggestive evidence that these differences may relate to individual LOC style. We recommend encouragement of patient participation to engender at least the perception of control in clinical situations involving acutely painful procedures.