Children's fuzziness leads to increased variance in the data, data loss, and high dropout rates in developmental studies. This study investigated the importance of 20 factors on the person (child, caregiver, experimenter) and situation (task, method, time, and date) level for the data quality as indicated via the number of valid trials in 11…

Because of their efficiency and ability to keep many other factors constant, twin studies have a special appeal for investigators. Just as with any teaching dataset, a "matched-sets" dataset used to illustrate a statistical model should be compelling, still relevant, and valid. Indeed, such a "model dataset" should meet the…

To make a scientific contribution, a reanalysis must be firmly rooted in the identification of a clearly superior methodological innovation over the original research. By contrast, a reanalysis rooted in dissatisfaction with previous results will necessarily be biased and can only obscure scientific discoveries. The reanalysis published by…

The two studies reported here sought to discover to what degree tracking activities are supported by the displacement of an object relative to a background in contrast to displacement of the whole field. (Author/RK)

The main objective of the present investigations was to determine whether or not young human infants see the physical spectrum in a categorical fashion as human adults and animals who possess color vision regularly do. (Author)

Data from infants unable to complete experimental sessions were compared to those for whom there were complete data. Results suggest that the elimination of large numbers of infants may have a potentially biasing effect on reported data. (Authors)

Demonstrated that time sampling is inaccurate for estimating durations or frequencies of behaviors. Also concluded that (1) individual or group differences can change depending on whether time sampling or continuous sampling is used; and (2) error rates are high when bout lengths of behaviors are short or when interval length is long. (BC)

This report concerns the field procedures and data analysis being used in the New York City Infant Day Care Study, a large-scale longitudinal study examining publicly-funded, community-controlled group and family day care programs in New York and comparing the effects of these programs and of home rearing on children and their families. Children's…

Three investigations are reported which indicate that infants between 4 and 17 weeks of age are able to detect some differences in sounds upon which phonemic contrasts are based. (Authors)

Notes two faulty aspects of the Reznick et al., twin study (PS 526 688): the expressive language measure at 14 months, which has practically no spread of item difficulty, as well as measures included to assess specific cognitive characteristics; and the notion of infant transition as it affects interpretation of the results. (HTH)

This study investigated whether behavioral inhibition is best conceptualized as a continuous variable or as a distinct typology with two or more subcategories. The following data were gathered on 58 infants at 5, 7, 10, and 13 months of age; physiological functioning (cardiovascular activity and salivary cortisol); emotional expressivity in…

This report provides an account of the nature and purposes of data collected concerning the health, nutrition, and physical development of infants during the first three years of life, in order to compare the physical health of children in family or group day care and children with no previous day care experience. The data collected include the…

The relation between maternal presence and infant's vocalization depended upon the infant's state: when the infant was in the active awake state, he vocalized less in the presence of the mother than when alone, thus indicating that the majority of early vocalizations are associated with a non-social situation. (Authors/RY)