Figure 2.

Key transitions coded by adaptation regressors in the categorical model. The stimulus presented on each trial “n” was labeled using both direct effect and adaptation regressors. Direct effect regressors code stimulus type. For the categorical model, all faces with 67%+ expression “A” were coded as “end A” (e.g., “surprise,” shown in green), those with 67%+ expression “B” were coded as “end B” (e.g., “fear,” shown in pink), and the 50/50 morph was coded using a third separate regressor. Adaptation regressors describe the difference between the stimulus on trial n and the stimulus on trial n − 1. These are illustrated here for the surprise-fear continuum. “Surprise <> fear”: transitions between any face from the surprise (green, “A”) end of the continuum and any face from the fear (pink, “B”) end of the continuum, where either face type can occur at trial n − 1 or trial n (note, all adaptation effects are coded symmetrically). (ii) “50/50 <> fear”: transitions between a 50/50 surprise/fear morph and a fear (“B”) end face, (iii) “50/50 <> surprise”: transitions between a 50/50 surprise/fear morph and a surprise (“A”) end face. Adaptation regressor values for the additional graded (linear) adaptation model can be found in Figure S2.