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KEEPING KIDS ON TRACK: INTERACTIVE EFFECTS OF AGE AND INTERVENTION
L.A. Roggman, L.K. Boyce, and G.A. Cook
Utah State University
"Time and experience . . . alter all perspectives." Henry Adams
Early Head Start interventions take place over time during the early years when development is like a fast-moving train that can get off track. Development in the first three years is rapid but vulnerable and demanding--infants and toddlers need a lot of support for their development to stay "on track." The second year of life is particularly critical for this support and thus for intervention, as both social and cognitive development are becoming more stable, and developmental trajectories are becoming increasingly differentiated (the "rich" are getting richer, the "poor" poorer). Early Head Start is trying to help keep children who are at risk because of poverty on track developmentally so they make the same gains as children in better circumstances. The goal of Utah's Bear River Early Head Start program is to improve the developmental outcomes for infants and toddlers by helping parents provide the experiences infants and toddlers need for social and cognitive development. To test whether these Early Head Start children are more on track, it is essential to look at the interactive effects of Early Head Start with regard to developmental change over time, especially in the second year of the child's life. By looking at the combination of developmental change (comparing tests at two ages) and intervention (comparing Early Head Start to a control group), we can see a pattern of effects that takes into account both maturation and environmental support. We included both age and intervention groups in our data analyses to see if the developmental track or trajectory is different for children in Early Head Start compared with those in the control group in two critical outcomes of early development: attachment security and cognitive skills. This approach to analysis is different from that used for the national cross-site study because it considers both age and intervention together by comparing changes from one age to another in the Early Head Start program group versus the control group.
Our Early Head Start local research project included mothers who were either pregnant at the time of enrollment or had infants less than 10 months old. To meet program requirements, over 90 percent were low-income as defined by federal poverty guidelines, and most families (97 percent) received some sort of public assistance such as Medicaid, food stamps, or WIC. Most children were white (82 percent) compared with 11 percent Latino and 7 percent other. Their mothers were mostly married or living with a partner (73 percent), over age 19 (75 percent; mean age = 22.9), had at least a high school education (65 percent), and were not working (79 percent). Family size at enrollment ranged from zero to seven children. Data for this study were from interviews with mothers before enrollment and again when the infants were 14, 18, and 24 months old. Attachment security was assessed using the Attachment Q-Set (Waters 1987) at 14 and 18 months; cognitive skills were assessed using the Bayley Scales of Infant Development at 14 and 24 months.
One strategy for examining both age and intervention group is to directly test the statistical interaction of age and group to see if change over time is different for children in the Early Head Start program group compared with those in the control group. Results of between-group repeated measures (by age) analyses of variance showed that, for both attachment security scores and cognitive skills scores, there were statistically significant interactions between age and group (for security scores F [1,137] = 8.9, p = .003, for Bayley scores F [1, 115] = 4.2, p = .04). This means that, for both attachment security and cognitive skills, age changes were different for those in Early Head Start compared with those in the control group. Simple effects tests were used to test age changes within each group: the Early Head Start group and the control group. For attachment security, only Early Head Start toddlers showed a statistically significant increase in their security scores from 14 to 18 months, as is expected developmentally, while control group toddlers did not increase their security scores with age (simple effects test for Early Head Start group, F [1, 137] = 8.2, p = .005). For cognitive skills, Early Head Start toddlers maintained stable standardized test scores that did not change with age, while control group toddlers, similar to others in poverty, began to lose ground, as indicated by a statistically significant decrease in their standardized cognitive skill scores (simple effects test for control group, F [1, 115] = 9.4, p = .003).
In summary, the developmental track is already different for toddlers compared with those in the control group. Utah's Bear River Early Head Start seeks to improve the expected outcomes of infants and toddlers by helping parents support their developmental gains. On average, toddlers in this Early Head Start program are becoming increasingly secure in their attachments to their primary caregivers, and they are maintaining age-appropriate progress in their cognitive skills. In contrast, toddlers in the control group did not show similar progress with age in either of these domains--they did not increase their attachment security or maintain age-appropriate cognitive skills. By examining both time and intervention, our results indicate a different developmental trajectory for Early Head Start toddlers compared with those in the control group. Toddlers in Early Head Start are staying on track because, as the research literature has shown, attachment security predicts later positive social behavior and early cognitive skills predict later academic readiness. In contrast, toddlers in the control group are beginning to get off track. These differences are likely to become greater with time, favoring those on a better developmental trajectory.
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