Co-speech gesture reveals the spatial foundation of children’s conceptions of time

Humans use space to make sense of abstract concepts. Across cultures, for instance, adults rely on mental timelines that conceptualize time metaphorically as a spatial path. Are these spatial models late-arriving "flourishes" or early-developing "foundations"? On the flourish account, spatial models are late ontogenetic additions, acquired only after a conceptual domain has been mastered. Alternatively, spatial models may be an early foundation that precedes and perhaps enables more elaborate understanding. Here, using spontaneous co-speech gesture as a window onto implicit spatial thinking, we show that children as young as five, who are still struggling to understand basic temporal concepts, nevertheless conceptualize time spatially. When US American children discussed temporal concepts, they gestured spontaneously in ways that represented time as a spatial path: past to one side, present at their body, future to the other side. These gestures typically aligned with cultural conventions, were shaped by brief exposure to a cultural artifact that represented time, and predicted the depth of children's temporal understanding. Spatial models may offer an early developmental foundation for elaborate conceptions of time.