The experiment was divided into two 1-h sessions. Sessions were at least 2 days apart (M = 3.05 days). In each session participants categorized target faces in a two-alternative forced choice paradigm following adaptation to the blank face, same-identity disgust face and different-identity disgust face. In one session target faces were NR’s neutral–anger morphed expressions and response options were ‘neutral’ and ‘anger’. In the other session target faces were F07’s happy–anger morphed expressions and response options were ‘happy’ and ‘anger’. The order of sessions and response buttons was counterbalanced across participants. Each session started with a short practice followed by six blocks of trials; two repetitions of each adaptation condition (control, same-identity disgust, different-identity disgust). Each block began with an adapting stimulus presented in the middle of the screen for 60 s that participants were told to look at thoughout this period. The adaptation period was immediately followed by 500 ms of blank screen then 57 trials (three repetitions of the morph continuum). At the start of each trial the adaptor presented during the adaptation period appeared for 5 s. This was immediately followed by the orientation stimulus presented for 150 ms, and a target face presented for 400 ms. Finally, a question marked appeared and remained on screen until the participant responded (see Fig. 1). The inter-trial interval was 500 ms blank screen. The order of stimuli was randomized within each block and the order of blocks was pseudo-randomized across the session (avoiding back-to-back presentation of the same adaptation condition). Each block lasted approximately 7 min. Participants were given a 1 min break at the end of each block.