Effective screening requires an understanding of underlying conceptual
issues and their relationship to pragmatic concerns. Pragmatic concer
ns include the concepts that there are many underlying reasons for an
''abnormal'' screening result; that sensitivity and specificity should
be combined with relative risk when considering developmental outcome
; and that patterns of congruence among motor, language, cognitive, an
d adaptive/personal social areas of development should be considered.
Important conceptual issues include the following: there is continuity
of underlying processes or functions in development; canalized behavi
ors might give the appearance of discontinuity; integrated functions a
re more predictive of later developmental levels than are individual f
unctions; the ''window'' of assessment and the developmental emergence
of a specific function will affect screening results; one must consid
er biologic and environmental risks and their specific effects; and di
fferent types of neural structures and their relationship to environme
ntal input help to explain why screening results vary over time.