Infant and preschool mental and verbal abilities: How are infant scores related to preschool scores?

The present study examined two different systems for creating subscales for the Bayley Mental Development Index. The purpose was to determine how performance on Bayley MDI subscales at 1 and 2 years of age is related to performance on the Standford-Binet IV at 3 through 5 years of age. The purpose was also to determine how the correlations for global and specific skill scores change as time intervals between assessment points increase. The results show that first year MDI and subscale scores were weak correlates of two-year MDI and subscale scores and preschool scores on the Stanford-Binet. Stronger correlations were found between two-year scores and Stanford-Binet IQ and Verbal Reasoning scores. The data show similar stabilities between the measures of global functioning (MDI and IQ), and between early and later measures of verbal abilities beginning after 2 years of age.