also includes parent time spent on developing relationships and acquiring knowledge, as well as the extent to which structured learning opportunities are embedded in typical family routines. Indeed, the ultimate impacts of such programs are presumed to be dependent on the degree to which families are able to incorporate specific intervention techniques into their everyday interactions with their children (Gilkerson and Stott, 2000).

Finally, both empirical data and clinical experience indicate that earlier identification and intervention are more important for some conditions or circumstances than for others. For example, early diagnosis and treatment is clearly effective in reducing the adverse impacts of a hearing loss on functional communication and cognition (Brasel and Quigley, 1977). Similarly, early tactile/kinesthetic stimulation of premature newborns has been associated with greater weight gain, higher survival rates, and higher neurobehavioral scores (Field et al., 1986). Children who are adopted out of institutionalized orphanages before 12 months of age have better developmental outcomes than those who are adopted at an older age (Benoit et al., 1996). The impacts of prenatal home visits have been correlated with enhanced health and safety outcomes and decreased parental interaction difficulties for some groups but have shown minimal effects for others (Olds and Kitzman, 1993). The persistent effects of the Abecedarian Project have been attributed by some investigators to the initiation of the intervention in early infancy and its extension over the first five years of life.

In summary, earlier has been shown to be better (and defined differently) for some conditions than for others. There is no basis, however, for concluding that individualized interventions provided after certain ages can have no positive impacts. Furthermore, notwithstanding the importance of preventing early developmental concerns from becoming more serious problems later, the premature initiation of services may lead in some circumstances to inappropriate labeling or the removal of children from typical experiences, thereby reducing the possibility of self-righting corrections or compensatory growth spurts. Finally, questions about intensity and duration must always be considered in the context of assessing the ratio of costs to benefits. Modest benefits from shorter and less intense services may be small, but their cost is relatively low. In contrast, significantly higher benefits may be derived from longer and more intense services, but the cost of those greater gains may be quite high.

Weighing the difference between costs and benefits in the determination of appropriate program “dosages” is a critical policy challenge. Unfortunately, the data needed to assess this issue are quite limited. Moreover, it is most important to recognize that the only way to provide definitive answers to questions about the relative impacts of the timing, intensity, and duration of service delivery is to conduct randomized experimental studies on specific populations.

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