Children's judgments of relative number by one-to-one correspondence: A planning perspective

Factors influencing the use of a plan to judge the relative number of two sets by one-to-one correspondence were studied in three experiments with 4- and 5-year-old children. The plan used by a child was assessed by the pattern of responses shown over a series of different types of problems in which sets were arranged in parallel rows. One-to-one plans were used by children only when perceptual support was present that facilitated the pairing of elements. When the support consisted of lines that connected the elements in pairs, one-to-one plans were used spontaneously by nearly all children. When the support consisted of enclosing pairs of elements in the windows of a grid, one-to-one plans were not used initially but were adopted after the children had received experience in pairing the elements. The results were interpreted as indicating (a) that most children have one-to-one plans in long-term memory by 4 years of age and (b) that young children fail to use one-to-one plans in some situations either because they fail to retrieve them from memory or because they reject them as unworkable.