Fear and time: Fear speeds up the internal clock

•The effect of emotion (Fear) on time perception was tested with durations from hundred of milliseconds to several seconds.•The stimulus durations were judged to be longer with high-arousal emotional stimuli.•The emotion-related time distortion increased with the length of durations.•The hypothesis that emotion of fear speeds up the internal clock is validated. We tested time perception in a bisection task featuring a wide range of durations (from 0.2 to about 8.0s) and highly arousing stimuli (delivery of an electric shock). In addition, self-report questionnaire responses and skin conductance responses were assessed to measure emotional reactivity. Results clearly demonstrated emotion-related time distortion, as stimulus durations were judged to be longer in the trials with an electric shock than in those without one. In addition, this lengthening effect increased with the length of durations. These findings are consistent with the hypothesis of an arousal-induced speeding up of the internal clock system.