Using the comparative model, the development of children with visual impairments is evaluated against norms based on children with vision. The use of this research model has generated a considerable literature, which in turn has produced a particular view of children with visual impairments. In brief, this view is that the eventual level of their abilities may be adequate, but that their developmental progress is delayed. At any given age, they tend to show lags, so that their level of development is delayed by some time in relation to sighted children.

This view leads to a certain set of expectations of children with visual impairments. If a parent of a blind infant were to ask a social worker or other blindness professional what the prospects are for that infant (and later child), the professional would look to the comparative literature and would reassure the parent that the child will acquire a set of adaptive abilities, but that he or she will do so at a slower developmental pace than would be expected of a sighted child. The key sentence, intended to be both realistic and reassuring, might be, “You cannot expect a normal rate of development, and you should not be disappointed by a pace that is delayed in comparison to your sighted children.”

The well-meaning professional is accurate in reading the existing literature this way. In normative terms, children with visual impairments are indeed delayed in many aspects of development. However, there is a most serious problem with this conclusion, no matter how well it is based in the comparative literature.