O'Neill looked at several aspects of children's storytelling ability. Some aspects captured grammatical complexity, such as children's use of relative clauses or the length of their sentences. Other aspects involved more perspective-taking on the part of the child.
Two years later, the children were brought back to the laboratory and were given a number of tests of academic achievement that included a test of mathematical achievement. What O'Neill found was that those children who scored highly on the mathematics test had also scored highly on certain measures of their storytelling ability two years earlier.