How children generate numbers

Several theories suggest that children learn natural number concepts via the acquisition of numerals, or symbolic representations of number like verbal numerals (e.g., “thirty-seven”) and Arabic numerals (e.g., “37”). Despite this importance, few studies have systematically investigated how children understand the structure of numerals. Here, we tested how numerals influence children’s numerical thinking in a free-response task. A convenience sample of 248 English-speaking 4- to 8-year-old children participated through Lookit, an online platform for asynchronous developmental science research. On verbal numeral trials, children were asked to say a number larger than the probe number they heard. On Arabic numeral trials, children were asked to write down a number larger than the probe number displayed. Children’s response patterns were analyzed across numeral format (i.e., Arabic/verbal), syntax, and age. We found that regardless of format, children were influenced by the syntax of the probe numeral with a tendency to keep the given syntax. Specifically, the most frequent response pattern was to only change the head digit of the given numeral, and this tendency increased with age. Uncanonical use of verbal numerals (e.g., responding “ten hundred thousand” to “nine hundred thousand”) and other error patterns suggested that syntactic complexity contributes to the difficulty of number acquisition. Our study exemplifies how an open-ended task can reveal children’s numerical thinking in an ecologically valid context. We encourage researchers to explore additional related research questions using the publicly available dataset.