Fast comprehension of embedded geometrical primitives and rules in human adults and preschoolers  Studies of sequence learning have outlined one possible mechanism by which complex mental representations are constructed out of simpler primitives: the human ability to extract complex nested structures from sequential inputs.  Experiments in infants, preschoolers, and adults without access to education have demonstrated the existence of innate "core knowledge" for space, endowing humans with spontaneous intuitions of geometry.  The question therefore arises whether a capacity for the internal representation and manipulation of nested sequences also underlies the acquisition of mathematics.  We propose to formalize the human sensitivity to mathematical rules through a "language of thought" that allows the formation of complex representations from a small repertoire of primitives. d' CONCLUSIONS  Simple rotations and axial symmetries were all detected and quickly used by human adults and 5-years-old children. Point symmetry was more challenging for French preschoolers or Munduruku adults than for French adults.