Spatial cognition is central to human behavior, but the way we conceptualize space varies over development and across cultures. When remembering the locations or movements of nearby objects, educated adults predominantly rely on a body-based spatial reference frame (e.g. to the left), whereas other groups prefer environment-based frames (e.g. toward the road), at least in some contexts. We propose that this variation in spatial thinking partly reflects differences in the ability to reliably discriminate left-right space, an ability that is common only among educated adults. To evaluate this proposal, here we tested US children’s spontaneous use of spatial reference frames on two axes. On the front-back axis, where spatial discrimination was relatively high, participants remembered object locations and movement directions using a body-based reference frame. On the left-right axis, where their spatial discrimination was significantly worse, the same participants preferred environment-based reference frames. This reversal reveals remarkable flexibility in children’s spontaneous use of spatial reference frames, extends findings in indigenous adults, and clarifies the likely mechanisms underlying spatial cognitive diversity.