Can the lateral mental timeline be automatically activated in language comprehension?

• Significant lateral space–time congruency effects in explicit (time-relevant) task. • Non-significant congruency effects in implicit task (lexical decision). • Same findings in keypresses, mouse trajectories, and long lateral movements. • We report the first confirmatory (preregistered) study in this debate. • The lateral mental timeline is not automatically activated in lexical decision. The mental representation of time recruits spatial representations, but is space an essential, inescapable feature of mental time? Supporting a positive answer to this question, recent research has reported that lateral (left–right) space is automatically activated in lexical decision tasks in which the temporal reference of the words is irrelevant for the goals of the task (implicit tasks). Here, using always the same set of Spanish verbs and pseudoverbs marked for past or future tense, we assess the space–time congruency effect in reaction time and mouse trajectories, both in an explicit time judgement task and an implicit lexical decision task. Moreover, we report the first confirmatory (preregistered) study in this field of research using long lateral movements in lexical decision. The congruency effect was always significant in time judgement, but non-significant in lexical decision. Moreover, in reaction time this effect was significantly smaller than a Smallest Effect Size Of Interest (SESOI) of 10 ms, and even smaller than a recently reported 9 ms effect. Therefore, it was considered negligible. We conclude that there is no convincing evidence for an automatic activation of the lateral mental timeline in lexical decision.