Mapping Time Across Spatial Axes: Mental Timeline Development in 3- to 5-Year-Old Mandarin-Speaking Children.

The present study investigated how Mandarin-speaking 3- to 5-year-olds map temporal sequences onto three spatial axes: sagittal, vertical, and horizontal. Two experiments were conducted. In Experiment 1, children arranged pictorial event sequences along each axis. In Experiment 2, they chose between ordered and unordered temporal sequences in a simpler choice task. Across the preschool years, children showed increasing use of spatial structure to represent time, but the pattern varied across axes. In Experiment 1, responding in the conventionally coded direction appeared earlier on the vertical and horizontal axes than on the sagittal axis. In Experiment 2, children's selection of ordered chronological sequences increased with age and was already detectable in the youngest group, although ordered-sequence choice remained relatively weaker on the sagittal axis. These findings suggest that early mental timeline development involves not only growing sensitivity to ordered temporal structure, but also the gradual coordination of temporal order with spatial direction through axis-specific linguistic, cultural, embodied, and task-related factors.