How children interface number words with perceptual magnitudes

How do children map symbolic number words to continuous and noisy perceptual magnitudes? We explore how 5- to 12-year-olds attach novel units to number, length, and area by examining whether verbal estimation performance is primarily predicted by access to number words, the precision of children’s underlying perceptual systems, or a more general process in structurally aligning number words with perceptual magnitudes. We find that from age five onward, children can readily form novel mappings between number words and perceptual magnitudes, including dimensions they have no experience estimating in (e.g., length, area), and even when faced with completely novel units (e.g., mapping a collection of three dots to “one” unit for number). Additionally, estimation performance was poorly predicted by the noise in their underlying perceptual magnitudes and number word access. Instead, we show that individual differences in children’s abilities to translate continuous perceptual signals into discrete categories underlie verbal estimation performance.