sensitive (or critical) period
a time when a child is espe- cially responsive and able to learn a particular skill.
sensory decit a loss in one or more of the
ve senses: vision, hearing,
touch, taste, smell.
Early Intervention and Public Policy
points in time, known as developmentally sensitive or critical periods. During these periods, the child appears to be especially responsive and able to learn from specic kinds of stimulation. The same stimulation at other times seems to have little impact on development. It is important that all children be in an enriched and responsive learning environment during these periods. For children with developmental problems, this may be even more essential (Olswang & Bain, 1991).
A developmental disability or delay often prevents a child from reacting in ordinary ways during a sensitive period. Parents, especially if they are inex- perienced, may not recognize signals from their child or they may read these signals incorrectly. In contrast, teachers in an inclusive classroom, where there is a range of developmental differences among children, tend to pick up on many subtle behavioral variations and many different forms of communication.
Critical learning periods that are not recognized and not used are common among infants and children with sensory decits. Think of the learning experi- ences so readily available to children who are non-disabled: hearing the differ- ence between the doorbell and the telephone; puzzling over a bird call, a ash of lightning, or an angry face. The typically developing child turns automatically, dozens of times a day, to look at and listen to and learn from specic things at specic moments. These same cues, quite literally, are not there for the child with a sensory decit. Without special assistance and opportunities to follow the leads of other children who are responding to what is going on, the child with a sensory impairment is isolated from everyday events.
Language acquisition appears to be especially tuned to a sensitive period in development. A child with a hearing impairment may never acquire truly adequate language if the hearing loss is not treated prior to what is thought to be the critical period for language development. On the other hand, a child whose hearing problem is identied early may experience fewer problems in language development. A combination of appropriate treatment and a special education program for children with hearing impairments or an inclusive pre- school (or a combination, depending on the child’s age and severity of hearing loss) allows critical learning periods to be built on as they occur.
Children who are physically disabled also are denied critical learning opportunities, but for different reasons. Many cannot move around. They can- not explore their environment. They may not be able to open doors, get into cupboards, run to the window, or learn by simply getting into mischief. Con- trast this with physically able children who are on the move from morning to night. They are touching, reaching, running, tumbling, climbing, getting into this and that. They try adults’ patience at times, especially during critical learning periods, when they seem to be in constant motion, as in the following example:
The infant who is learning to walk is forever on the go. Once walking is mastered, a great cognitive advance seems to take place. Then comes another surge of motor development. The child learns to run, jump, and climb, practicing these skills relentlessly. On the other hand, children who