Does the congenital blind have space-time mapping on the sagittal axis?

Previous evolutionary perspectives proposed strongly that the space-time mapping on the sagittal axis originates from visual-locomotor coupling when walking/running forward. Thus, the congenital blind could not have the sagittal mental timeline. However, this conclusion was reached with single empirical evidence (Rinaldi et al., 2018) and requires corroboration from converging evidence using diverse methodologies. The present study systematically explored whether the congenital blind has space-time mapping on the sagittal axis using different paradigms in three experiments. In Experiment 1, the congenital blind showed preferred space-time mapping in the sagittal dimension as normal sighted using a typical implicit RT task. In Experiment 2, this space-time mapping could even occur automatically when using a temporal judgment irrelevant naming task. In Experiment 3, the congenital blind was more likely to put the past time behind the body and to put the future time in front of the body in an explicit space-time mapping task. Moreover, most blinds use spatial metaphors to make this space-time mapping on the sagittal axis. These results support that the congenital blind could have a sagittal mental timeline, and the visual-locomotor coupling experience was not critical for this space-time mapping. Taken together, the present study helps to clarify the long-standing debate on the origin of the sagittal mental timeline.