These various definitions have been codified in federal and state statues. As new research becomes available and challenges existing models of LD, these definitions will likely change. The term includes such conditions as perceptual handicaps, brain injury, minimal brain dysfunction, dyslexia, and developmental aphasia. A learning disability is characterized by a difference in a child's achievement in a particular area when compared to his or her general ability. Ability is typically measured by intelligence tests, while achievement is seen in school performance and standardized evaluations.
People can have learning disabilities in math, reading, writing, motor or other skills.
While the definition quoted here differs slightly from that given in the Diagnostic and Statistical Manual for Mental Disorders, both emphasize the importance of distinguishing between learning disabilities and other problems that might affect a person's ability to learn. Causal factors of learning disabilities include genetic factors, birth injuries, high fevers, and head injuries. Oftentimes more than one member of a family has a learning disability, though families do not cause learning disabilities. A learning disability is intrinsic in nature and should be considered a life-long handicapping condition. Simply underachieving or learning slowly does not constitute a learning disability.