Figure 2. Mean salivary cortisol concentrations obtained before and after consuming placebo or 50 mg naltrexone and after the nociceptive flexion assessments (details of the protocol outlined in Figure 1) for low-risk (A) and high-risk (B) participants. A significant risk x medication x sample interaction was found (p < .05) reflecting an early peak in cortisol concentrations in the naltrexone condition among the low-risk participants. Error bars represent standard error of the mean.