Context-dependent categorical perception of surprise

Evidence regarding the categorical perception of surprise facial expressions has been equivocal. Surprise is inherently ambiguous with respect to valence: it could be positive or negative. If this ambiguity interferes with categorical perception, disambiguating the valence might facilitate categorical perception. Participants identified and discriminated images that were selected from expression continua: happy fear, surprise fear, happy surprise. Half were presented with a context for the surprise expressions indicating positive or negative valence. Both groups had a typical identification curve, but discrimination performance was better predicted by identification in the context condition for happy fear and surprise fear continua, suggesting that categorical perception was facilitated by the disambiguating context.