"The delicate tremble of a butterfly's wings in my hand, the soft petals of violets curling in the cool folds of their leaves or lifting sweetly out of the meadow-grass, the clear, firm outline of face and limb, the smooth arch of a horse's neck and the velvety touch of his nose - all these, and a thousand resultant combinations, which take shape in my mind, constitute my world." - Helen Keller
Our senses unite to give us representations of the world. When one modality is lost, distortions and confusion result, but the solution is interact even more with the world. In the figure below, researchers find that blind and control subjects activate similar areas for similar objects. Sighted people see a tube of toothpaste and have a tactile imagery of what it feels like. Blind people only have a tactile imagery. But the image is a representation or a generalization that the brain makes about what it is. And imagery is formed by an ongoing feedback between the senses and the brain.
There are many conditions that give rise to sensory processing disorders in children...the most common are probably mild birth injury or a inherited disability. Children who have inconsistent imagery for steps, escalators, dogs, and new environments will be afraid of all these things. Over time (if left to their own devices), they will explore less rather than more. What parents, therapists, and teachers can do is guide them in their exploration and help them to gain confidence with understanding their world with whatever intact senses they have. These general principles apply to many children with sensory disorders (for instance those with visual or auditory perceptual abnormalities or those with impaired position sense).
In the figure below, the top picture shows the pattern of brain activation in sighted test subjects. Note the overlap between touch and sight. Below is a simlar representation observed in blind subjects that used touch alone.
When Sight is More Than Sight