Fig. 4. Heat pain threshold and temperature-dependent fractional inhibition.

(A to D) Shift in temperature required to induce the same pain rating. (E to H) Temperature-dependent fractional inhibition of the heat-induced pain by the antagonist. (I to L) Maximum pain ratings in injections without the antagonist (red) versus injections with the antagonist (ochre). Data are estimates with 95% CIs. (M to P) Modeled probability to distinguish the heated injections from the individual three injections at room temperature in the presence and absence of the respective antagonist. Each participant had four injections without the antagonist (red) versus injections with the antagonist (ochre). Data are estimates with 95% CIs.