Action observation triggers by default a mental simulation of action unfolding in time. We assumed that this simulation is “embodied”: the body is the medium through which observer’s sensorimotor modalities simulate the observed action. The participants in two experiments observed videos, each depicting the central part of an action performed by an actress on an object (e.g., answering the phone) and soon after each video they observed a photo portraying a state of the action not observed in the video, either depicting the initial part or the final part of the whole action. Their task was to evaluate whether the photo portrayed something before (backward photo) or after the action in the video (forward photo). Results showed that evaluation of forward photos was faster than evaluation of backward photos (Experiment 1). Crucially, participants’ body posture modulated this effect: keeping the hands crossed behind the back interfered with forward simulations (Experiment 2). These results speak about the role of the observer’s body posture in processing other people’s actions.

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Discourse comprehension relies on the construction of a mental model that represents the unfolding in time of the events described. In causal scenarios, where the action of one agent (the enabler) temporally precedes and enables the action of another agent (the causer), discourse may reflect the underlying event structure by describing the enabler’s action first and then the causer’s action (story order) or may describe the causer’s action first (backward order). Studies in the literature have shown that adults consider causers to be more responsible than enablers in moral scenarios. Based on the assumption that story order favors the construction of a mental model of events, we conducted an experiment to test the prediction that preference for the causer over the enabler should be greater when events are presented in story order than in backward order. The participants in the experiment were 42 fifth-grade children, 42 adolescents, and 42 adults. The results of the experiment confirmed the prediction for all three groups of participants. We discuss the practical implications of these results for learning contexts, legal contexts, and the psychology of moral judgments.

The main assumption underlying the present investigation is that action observation elicits a mandatory mental simulation representing the action forward in time. In Experiment 1 participants observed pairs of photos portraying the initial and the final still frames of an action video; then they observed a photo depicting the very same action but either forward or backward in time. Their task was to tell whether the action in the photo portrayed something happened before or after the action seen at encoding. In this explicit task the evaluation was faster for forward photos than for backward photos. Crucially, the effect was replicated when instructions asked only to evaluate at test whether the photo depicted a scene congruent with the action seen at encoding (implicit task from two still frames, Experiment 2), and when at encoding they were presented a single still frame and evaluated at test whether a photo depicted a scene congruent with the action seen at encoding (implicit task from single still frame; Experiment 3). Overall, the results speak in favour of a mandatory mechanism through which our brain simulates the action also in tasks that do not explicitly require action simulation.