Estimating one's own systolic blood pressure: effects of feedback training

This study was aimed at discovering the ability of subjects to estimate absolute levels of systolic blood pressure after feedback of daily blood pressure information. Twenty-one subjects were studied who had shown a variation of at least +/- 20 mm Hg in systolic pressure during 8 days of base-line measurements. Subjects' estimates were found to be moderately accurate even before any specific blood pressure information feedback was given (mean error was +/- 12.4 mm Hg). Then during 15 days of information feedback, subjects' accuracy improved, e.g., for 10 subjects who were given correct information feedback the mean error was +/- 7.4 mm Hg, a highly significant improvement. This is a high degree of accuracy-especially in comparison with the mean variation of +/- 5.8 mm Hg from 1 min to the next in their systolic blood pressure. The learning of one's range of blood pressures appeared to be the principal component of the improvement. Range information had been provided by giving the subject his range of fluctuation for the 8-day base-line period, and by daily blood pressure information feedback immediately after each estimate. Two types of estimators were distinguished: Those who were relatively accurate versus those who were inaccurate in estimating at their own extremes of blood pressure. Those who were inaccurate at their own extremes (1) paid less attention to the feedback of information they were provided with as well as to the internal cues from their own blood pressure and (2) were more field independent.