Abstract

Available evidence shows that 7-month-old infants are able to represent and discriminate sequences whose numerical values increase or decrease by a 1:2 ratio, while 4-month-olds can represent and discriminate increasing ordinal sequences of elements that vary in size according to the same ratio. The aim of the current study is to investigate 4-month-old infants' ability to discriminate numerical ordinal sequences. Results demonstrate that 4-month-olds, unlike 7-month-olds, fail at discriminating inversions in order of numerical sequences that increase or decrease by a 1:2 ratio. These results are in line with the hypothesis, proposed by Brannon (2002), that the ability to detect order within size-based sequences precedes in development the ability to detect order within numerical sequences.