Embodied time: Effect of reading expertise on the spatial representation of past and future

How do people grasp the abstract concept of time? It has been argued that abstract concepts, such as future and past, are grounded in sensory-motor experience. When responses to words that refer to the past or the future are either spatially compatible or incompatible with a left-to-right timeline, a space-time congruency effect is observed. In the present study, we investigated whether reading expertise would determine the strength of the space-time congruency effect, which would suggest that learning to read and write drives the effect. We compared two types of space-time congruency effects, one where spatial incongruency was generated by the location of the stimuli on the screen and one where it was generated by the location of the responses on the keyboard. While the first type of incongruency was visuo-spatial only, the second involved the motor system. Results showed stronger space-time congruency effects for the second type of incongruency (i.e., when the motor system was involved) than for the first type (visuo-spatial). Crucially, reading expertise, as measured by a standardized reading test, predicted the size of the space-time congruency effects. Altogether, these results reinforce the claim that the spatial representation of time is grounded in spatially-directed movement, such as reading or writing.