Acute stress enhances sensitivity to a highly attractive food reward without affecting judgement bias in laying hens

•We assessed the effects of acute stress on affective states in laying hens.•The majority of hens learnt to discriminate two cues signalling differing rewards.•Acute stress and reward order affected speed of response to cues (arousal).•Stress did not affect active choice during ambiguous cues (valence).•Stress enhanced sensitivity to positive reward without affecting judgement bias.