DEMOS

Download the paper

Abstract

Behavioral, neuropsychological, and brain imaging research points to a dedicated system for processing number that is shared across development and across species. This foundational Approximate Number System (ANS) operates over multiple modalities, forming representations of the number of objects, sounds, or events in a scene. This system is imprecise and hence differs from exact counting. Evidence suggests that the resolution of the ANS, as specified by a Weber fraction, increases with age such that adults can discriminate numerosities that infants cannot. However, the Weber fraction has yet to be determined for participants of any age between 9 months and adulthood, leaving its developmental trajectory unclear. Here we identify the Weber fraction of the ANS in 3-, 4-, 5-, and 6-year-old children and in adults. We show that the resolution of this system continues to increase throughout childhood, with adultlike levels of acuity attained surprisingly late in development.

Methods

Method includes 3 practice trials and test trials (test trials show both sets simultaneously). Click play to view a trial.

Results

Scatterplot of the estimated Weber fraction for each age group from both the psychophysics model and the sigmoid model, combined with two estimates from the literature on infant Weber fraction displayed as a function of age. The estimated developmental curves are logarithmic least squares fits.