noun

inability or refusal to accept that something is true or real.

Laura shook her head in disbelief

incredulity,incredulousness,lack of belief,lack of credence,lack of conviction,scepticism,doubt,doubtfulness,dubiety,dubiousness,questioning,cynicism,suspicion,distrust,mistrust,wariness,chariness,bewilderment,bafflement,surprise,shock,stupefaction,confusion,perplexity