Temporal momentum: an online replication and beyond.

Performing mental arithmetic on brief temporal durations has been recently shown to induce operation-specific distortions. In a time reproduction task, addition resulted in longer responses while subtraction induced shorter responses, despite their identical arithmetic outcome (Bonato et al., Cognition, 206, 2021). This effect has been named temporal momentum, in analogy with the representational momentum found when representing the position of moving objects, and it mirrors the operational momentum characterizing mental arithmetic with numerical quantities. In Experiment 1, we assessed the reliability of the temporal momentum effect in the first direct replication of Bonato et al.'s temporal arithmetic task by using an online procedure for data collection. In Experiment 2, we also tested whether under-estimation in subtraction could be attributed to the longer operand being always presented first in the original study. The results showed a reliable temporal momentum effect that was virtually indistinguishable from previous, laboratory-based experiments. Moreover, in Experiment 2, under-estimation in subtraction was still present when participants had to compute the difference between two operands regardless of their order, thereby excluding that the temporal momentum in subtraction is due to the specific ordering of the stimuli. This pre-registered study further demonstrates that the temporal momentum effect is a robust and reliable marker indexing the mental manipulation of time durations, consistent with the hypothesis that time processing includes some features resembling those involved in spatial processing.