Perceptual relationships to peripheral venous tone.

IN AN experiment performed a few years ago [l], which involved periodic drawings of venous blood from an indwelling cournand needle, it was observed that it was more difficult to withdraw venous blood (from a superficial arm vein) in Field Dependent (FD) than Field Independent (FI) Ss. A variety of other investigations have suggested that these two groups differ in the degree to which they are able to analyze discrete elements of a percept [2]. FD Ss perceive globally, tend to make major errors in the Rod and Frame test, have difficulties in finding the hidden figure in the Embedded Figures test, and also perform poorly on a variety of other perceptual and sensory integrative tasks [3]. FI Ss, at the other end of the population distribution, tend to perceive analytically and have much less difficulty with these tasks. Indeed our previous investigations [4] have suggested that the poor perceptual organization of FD Ss may lead them to the necessity of remaining more chronically aroused in order to cope with the uncertainty of their environment. In experiments where stimuli are absent or unclear, FD Ss increase in arousal. Where stimuli are discrete, FD Ss decrease in arousal. (As our colleague Bertram Cohen has suggested this might be likened to the increased alerting and tension an auto driver experiences as he drives through a fog. When the fog lifts, permitting the perception of clear stimuli, he relaxes). The observation that venous blood samples were more difficult to collect from FD Ss suggested the possibility that their veins were more constricted because of the above noted tendency to be more centrally aroused; i.e. that the hypothalamus and other autonomic centers were in these Ss, chronically discharging impulses along sympathetic vasoconstrictive fibers leading to constriction of the veins. Thus, it was decided to measure venous pressure in isolated venous segments, and the prediction was made that during the initial rest periods (prior to any stimulus), venous pressures would be higher in FD than FI Ss. Our previous work [5] and that of others [6, 71 had suggested that when specific stimuli impinge, i.e. when “uncertainty” decreases, the psychophysiologic responses of FI Ss are greater than those of FD Ss. Thus it was also predicted that during periods of specific stimulation, the venous pressures of FI Ss would be higher than FD Ss; and that resting levels would be similarly affected, i.e. resting levels after stimulation would also show the above noted reversal, presumably because of the altered set, i.e. the decrease in uncertainty.