Although time perception has mainly been explored through the prospective paradigm, it appears that emotional stimuli lead to an overestimation of time either through an arousing or an attentional effect. Amongst the emotional stimuli, emotional expressions are of interest due to their social importance. The purpose of this paper was to systematically review research carried out into emotional expression interference on time perception. A systematic literature review of 13 peer-reviewed papers with an empirical design that tested healthy participants was conducted on studies exploring both time perception and emotional expression. Furthermore, the papers were only included if they were written in English language and dated from at least the year 1964 (i.e. following Treisman's model of time perception in 1963). Findings showed a congruent overestimation when participants were exposed to emotional faces, especially when they expressed anger. This interaction was mediated by the dynamism of the stimuli used (i.e. there was a stronger effect if the expressions were animated), the model gaze and direction (i.e. nullified effect when the face was directed away from the participant), the embodiment effect (i.e. nullified effect when participants could not mimic the expression), and participant age (i.e. stronger effect of positive expressions amongst elderly participants). In conclusion, it emerged that two underlying mechanisms explain the overestimation observed when confronted with emotional expressions-attention and arousal. Although these two mechanisms appear to impair time perception independently, the studies on the stimuli dynamism indicated a potential conjoint effect of these mechanisms
