AN EVALUATION OF FOREARM BLOOD FLOW AS A PSYCHOPHYSIOLOGICAL MEASURE

The usefulness of forearm blood flow (FBF) as a psychophysiological measure was investigated by comparing changes occurring during mental tasks in cardiovascular, sudomotor, and electromyographic measures. The measures were divided into those clearly physiologically independent and those physiologically related. ANOVA results showed that FBF, heart rate (HR), and skin conductance fluctuations (SCF) were equally reactive, and correlational analysis suggested that a close relationship existed between FBF, HR, and SCF, although correlations fell to near zero levels when intra-individual correlations were calculated with between task variance extracted. For some experimental purposes HR response may be considered equivalent to FBF response. The relationship between EMG and FBF was more variable, and tends not to support the idea that FBF is an indirect measure of muscle activity. The reliability of FBF in normal subjects at rest was poor, although it improved when measured during a simple task, and is probably stable enough for most experimental purposes.