Learning Disabilities

Learning disabilities is a heterogeneous disorder. The most common type of learning disability is language-based and due to difficulties with the sounding out of words—also called phonological coding deficits (Teeter and Semrud-Clikeman 1997). In this type of learning disability the child has difficulty hearing and/or understanding the differences in the sounds of a word (Mann 1991). For example, the word cat may not be heard as three different sounds—c a t. Reading requires that a child learn the relationship between the written letters and the sound segments—also called sound-symbol learning (Torgesen 1993). This is the most common type of learning disability.

Another type of learning disability involves difficulty with the visual or orthographic features of a word (Stanovich 1992). For example the outward configuration of words such as left and felt are relatively similar—high letter, low letter, two high letters—and may be confused by a child with this type of learning disability. These types of learning disabilities are less common. Visual memory is important in reading and children with this type of learning disability seem to have difficulty recalling what they see (Terepocki, Kruk, and Willows 2002). Children are evaluated in their ability to discriminate phonetically similar words like main from mane and homonyms (e.g., see and sea).

The majority of learning disabilities are reading based and most of the research involves children with reading disabilities (or dyslexia). However, it is important to realize that learning disabilities can also be identified in mathematics and written language. These types of learning problems are not as commonly evaluated or reported as a reading disability. Written language disabilities can have profound effects on a child's ability to generate and organize ideas in written form (Nodine, Barenbaum, and Newcomer 1985). Less is known about written language disabilities than reading disabilities but a study that evaluated children with brain injuries found that these children had intact reading skills but deficits in mathematics and written language, particularly if the damage was in the right hemisphere.

The incidence of math-based learning disabilities suggests that approximately 6 percent of children show a learning disability in this area (Miles and Forcht 1995). Difficulties can be found in mathematics calculations that are often related to difficulties with visual-spatial skills. Children with this type of disability may also show difficulties with social understanding. When mathematics problems and visual-spatial delays occur together, the child may have a nonverbal learning disability. These difficulties involve the child's inability to understand the context of the social situation, to interpret facial and body gestures, and to act accordingly. The relationship between the mathematics difficulties and these social deficits is not fully understood and further research is needed in this area (Semrud-Clikeman and Hynd 1990).