Figure 31-8 The role of opioid and hypnotics in the stimulus-response relationship for three stimuli of increasing intensity and three increasingly difficult responses to suppress. Each cell would have its own opioid-hypnotic interaction surface, and three are displayed. The vertical axis is the probability of nonresponse. Verbal nonresponsiveness to name calling is readily suppressed, even at light levels of anesthesia. In contrast, profound levels of anesthesia are required to suppress the hemodynamic response to intubation.