Of course, these model programs also differed in the focus of
the teachers and the program developers. For example, some focused
most intensely on cognitive development, while others focused
more on social and emotional development (Day and
Parker, 1977; Lazar et al., 1977). Despite their differences, the commonalties
reported above appear to be sufficient to ensure that all
of them produced significant gains in cognitive development.
However, program differences may have produced some differences
in cognitive effects and, to a greater extent, in social and
emotional development. Research comparing these programs
and others developed based on these models has accumulated
over the years and provides significant insights into the importance
of differences among the models.