The cues that infants use to distinguish discontinuous quantities: evidence using a shift-rate recovery paradigm

A novel experimental method, shift-rate recovery, was developed and used in a series of three experiments. These examined the extent to which 6-month-old infants (N = 131) find perceptual cues such as density and length useful in the discrimination of linearly arranged sets containing large numbers of objects. Results showed that infants discriminated between arrays that differ in number and density, with length held constant, when the arrays were presented either simultaneously or successively. On the other hand, infants discriminated only between arrays that differ in number and length, with density held constant, when the arrays were presented simultaneously. Infants were, however, able to perform a successive length discrimination when the arrays were continuous rather than consisting of discrete items. These findings support the conclusion that infants are able to discriminate between large number sets by relying on absolute cues such as density (but not length) and on relative cues such as optical one-to-one correspondence.