BLOOD-PRESSURE AND SENSITIVITY TO FLICKER

The relationship between acute changes in systolic blood pressure and visual sensitivity to flicker was examined. luminance thresholds for the detection of flicker were determined psychophysically. Systolic blood pressure was monitored continuously over the course of the experimental session. Fifteen subjects were tested and divided into two groups, those who demonstrated a substantial change in systolic blood pressure from a baseline measure (i.e., the ''reactive'' group) and those who did not (i.e., the ''nonreactive'' group). The reactive group showed an inverse relationship between changes in systolic blood pressure and flicker sensitivity measures. This relationship was statistically significant in seven of the eight subjects. For the nonreactive group, only one subject showed an inverse relationship between changes in systolic blood pressure and flicker sensitivity. Dworkin (1988) has suggested that acute elevations in blood pressure serve to inhibit sensory systems. The data from the present experiment are consistent with this hypothesis. A spectral analysis revealed statistically significant rhythms for both systolic blood pressure and flicker sensitivity in twelve of the Fifteen subjects. This replicates earlier reports of cycles (on the order of 3 minutes and longer) in systolic blood pressure and flicker sensitivity.