Fig. 3.

Placebo-induced changes in β-endorphins. Greater increases in β-endorphin plasma levels following the experiment were associated with higher expectancy of improvement on placebo (left) and mood ratings (right). Y-axis indicates expectancy or mood ratings (much better = 3, better = 2, slightly better = 1, no change = 0, slightly worse = −1, worse = −2, and much worse = −3). Error bars represent 95% confidence intervals