| Popis: |
A critical difference between decimal and whole numbers is that among whole numbers the number of digits provides reliable information about the size of the number, e.g., double-digit numbers are larger than single-digit numbers. However, for decimals, fewer digits can sometimes denote a larger number (i.e., 0.8 > 0.27). Accordingly, children and adults perform worse when comparing such Inconsistent decimal pairs relative to Consistent pairs, where the larger number also has more digits (i.e., 0.87 > 0.2). Two explanations have been posited for this effect. The string length congruity account proposes that participants compare each position in the place value system, and they additionally compare the number of digits. The semantic interference account suggests that participants additionally activate the whole number referents of numbers – the numbers unadorned with decimal points (e.g., 8 < 27) – and compare these. The semantic interference account uniquely predicts that for Inconsistent problems with the same actual decimal distance, those with a larger whole number distances should be harder, e.g., 0.9 vs. 0.81 should be harder than 0.3 vs. 0.21 because 9 << 81 whereas 3 < 21. Here we test this prediction in two experiments with college students (Study 1: n = 66 participants, Study 2: n = 85). Across both, we find both a main effect of consistency, reaffirming the string length hypothesis, but also that whole number distance interferes with processing conflicting decimals, supporting the semantic interference proposal. Evidence for both explanations indicates that decimal comparison difficulties arise from multiple competing numerical codes. |
