Development of Children's Estimation Skills: The Ambiguous Role of Their Familiarity With Numerals

Money counts: effects of monetary vs. purely numerical values on the mental representation of quantities

It has been established that humans use different cognitive models to represent and process numerical quantities. In this study, we investigated whether the representation of monetary values fundamentally differs from the representation of numbers. We also examined the influence of both socio/economic factors and mathematical ability on such representation. A group of adults (N = 272) were tested anonymously with a variant of the number-to-position task (Siegler & Opfer, 2003). They were asked to position on a horizontal line quantities expressed either in numerical format (e.g., 50) in the "Number" conditions or as monetary values (e.g., 50€) in the "Money" conditions. The extremes of the line consisted either of specific values (i.e. "2 or 2€" and "503 or 503€") in the "Fixed" conditions or of unspecific concepts of quantity (e.g., "little" and "a lot") in the "Fuzzy" conditions. A linear model, as opposed to a logarithmic one, provided the best fit of group average data in all experimental conditions except for the "Money-Fuzzy" condition. The percentages of absolute error were significantly larger for Money stimuli than Number stimuli in both Fixed and Fuzzy conditions. This is consistent with the law of diminishing marginal utility, which entails that the value of monetary quantities is described by a concave curve rather than a linear relationship. As expected from previous research, participants who were more used to spending large quantities of money were closer to the linear representation model. Participants with higher mathematical abilities represented numerical values more closely to a linear model, but no such effect was found for monetary quantities.

Number estimation in Down syndrome: Cognition or experience?

BACKGROUND

The ability to place numbers on a visual "number line" is a hallmark of the understanding of numerical magnitude and it is a strong predictor of mathematical achievement.

AIM

We examined whether the performance in the number line estimation task is more driven by mental age or experience with numbers in a sample of Italian children with Down syndrome (DS).

METHOD AND PROCEDURE

Sixty-three children with DS (M_months = 128.62, SD = 30.73) and sixty-three typically developing children (M_months = 54.98, SD = 6.34) matched one to one for mental age completed number line estimation tasks and other tests to assess their numerical knowledge.

OUTCOMES AND RESULTS

No significant differences emerged between the two groups in terms of accuracy of positioning numbers on the 1-10 and 1-20 interval. In addition, the accuracy on the 1-10 interval was related to the ability to recognize numbers, while the accuracy on the 1-20 line was related to the ability to compare magnitudes.

CONCLUSION AND IMPLICATION

Results suggest that in individuals with DS the linear mapping of numbers is driven by mental age, but the accuracy of positioning numbers is also shaped by the experience with symbolic numbers. Therefore, the improvement of numerical estimation abilities should be a target of intervention programs.