Can mental time lines co-exist in 3D space?

A growing body of evidence suggested that time can be represented separately either on the lateral, sagittal or vertical axis. However, it is still not clear whether these mental time lines from different origins could co-exist, or compete with each other such that if one is selected, the others are inhibited? The present study addressed this question using a multi-dimensional free-choice paradigm with Mandarin speakers in three experiments. The results showed that significant spatial-temporal congruency effects were found both on the lateral and sagittal/vertical axes in the horizontal/coronal plane either in a temporal judgment relevant or irrelevant task. By contrast, the spatial-temporal congruency effects did not appear at the same time on the sagittal and vertical axes in the sagittal plane. These results supported that lateral mental time line could co-exist with the other two, while sagittal and vertical mental time lines could not co-exist with each other. This finding implied that the space-time mapping mechanism is different between the lateral axis and the sagittal and vertical axes, whereas it is the same for the latter two axes.