Log or Linear? Distinct Intuitions of the Number Scale in Western and Amazonian Indigene Cultures

TLDR

The mapping of numbers onto space is a fundamental aspect of measurement and mathematics. The study asks whether this mapping is a cultural invention or a universal intuition shared by all humans. The authors examined number‑space mappings in the Mundurucu, an Amazonian group with a reduced numerical lexicon and little or no formal education. Across all ages, the Mundurucu mapped numbers logarithmically, while Western adults used linear mapping for small or symbolic numbers and logarithmic mapping for nonsymbolic numbers when counting was discouraged, indicating that the initial number‑space intuition is universally logarithmic and that the linear number line is a cultural invention that does not develop without formal education.

Abstract

The mapping of numbers onto space is fundamental to measurement and to mathematics. Is this mapping a cultural invention or a universal intuition shared by all humans regardless of culture and education? We probed number-space mappings in the Mundurucu, an Amazonian indigene group with a reduced numerical lexicon and little or no formal education. At all ages, the Mundurucu mapped symbolic and nonsymbolic numbers onto a logarithmic scale, whereas Western adults used linear mapping with small or symbolic numbers and logarithmic mapping when numbers were presented nonsymbolically under conditions that discouraged counting. This indicates that the mapping of numbers onto space is a universal intuition and that this initial intuition of number is logarithmic. The concept of a linear number line appears to be a cultural invention that fails to develop in the absence of formal education.