Fig. 3.

Left: amplitude of HEP difference scores (repetition—alternation trials) in response to pained, angry and neutral facial expressions in experiment 1. Positive waveforms highlight a higher amplitude in repeated relative to alternated trials. Negative waveforms highlight reduced amplitude in repeated relative to alternated trials. Right: box plots showing the interaction between the three levels of valence: HEP suppression to repeated angry expressions significantly differs from HEP elevation to neutral and pained faces (whiskers represent s.d.).