Adaptive systems using psychophysiological measures to assess and predict operator states are increasingly prevalent. Yet, the search for a more sensitive and accurate measure is a high priority. The current research investigated the responsiveness of baroreceptor sensitivity (BRS) to varying levels of a mental task (i.e., 1-back, 2-back, and 3-back) compared with other physiological variables (electroencephalogram (i.e., alpha power), electrodermal activity (EDA) (i.e., skin conductance level (SCL)) and to examine BRS's ability to predict performance and workload. Healthy males (n = 26) and females (n = 29) aged 18 to 30 years participated in the study. BRS during the 2-back and 3-back conditions were significantly lower than the 1-back condition (p < .05). Alpha power was significantly lower during the 2-back (p < .05) and 3-back (p = 0.074) condition compared to the 1-back. Skin conductance was significantly increased during the 3-back condition compared to the 2-back and 1-back (p < .05). Subjective workload was significantly increased with task difficulty (p <. 001) while performance decreased (p < 0.001). When combined with alpha asymmetry and SCL, BRS significantly added to the regression model predicting performance for the 3-back condition (p < .05) and was the only significant predictor (p < .05). When compared to other commonly used physiological measures, BRS was sensitive to varying levels of a mental task and predicted performance at high levels of a mental load.