Measures of Development
Measures of cognitive and speech and language development were obtained from the infants in our study. We also obtained a number of measures of caregivers’ interactions with the children. Most often the measures of the children that we selected were those frequently used by both practitioners and researchers with children in the age range o f 0 to 3 years. We also used mea sures that we ourselves developed based on the research literature. The source of a particular measurement, be it standard or developed by us, is indicated so that interested readers can examine the original data. In one instance, a research measure has been developed into a test and we provide the reference for this test. Measures of speech and language development are discussed separately. Although speech and language development are intimately related to each other they also represent distinct aspects of development. Speech is perceived and produced earlier than recognized categories of language such as words and sentences, and speech perception and production require somewhat different abilities than language production and perception.