Does past tense marking indicate the acquisition of the concept of temporal displacement in children's cognitive development?

The acquisition of past tense markers has often been considered to parallel conceptual development in the domain of time (e.g., Weist, 1986). However, the precise relationship between linguistic marking of time in childrenís speech and conceptual development has not been investigated in data-based research. This study analyses longitudinal speech data from four Japanese children to determine whether the use of the past tense form actually coincides with its use to signal past time. The results show that the relationship between contrastive use of the form and truly deictic past is not a straightforward one; for all the children, deictic use emerges later than the contrastive use of past and nonpast forms.