This is just one model of categorizing l.d. subtypes. One of the manifestations of a reading disability not shown here is difficulty processing signs and symbols which affects performance in math calculations and word problems. This type of underachievement in math may not involve higher order reasoning deficits but only mechanical perceptual problems.
One of the important facts to keep in mind is that if a student verified as learning disabled has one or more of the above characteristics, s/he has average to above-average intelligence that is expressed more freely in other ways. Feeling blocked from expressing what one knows is frustrating, and is not a sign of a lack of intelligence or knowledge.
Hoy, Cheri, et al. "Assessment and Remediation of Written Language." "Academic Assessment and Remediation of Adults with Learning Disabilities". Clarke County Board of Education, Athens, GA. 1984.
Rourke, Ph.D., Byron P, and Tsatsanis, Katherine. "Syndrome of Nonverbal Learning Disabilities: Psycholinguistic Assets and Deficits." Topics in Language Disorders 16.2 (1996): 30-44.
Shames, G. and Elisabeth Wiig. Human Communication Disorders. Columbus: Merril, 1986.
Wong, Bernice. The ABCs of Learning Disabilities. San Diego: Academic Press, 1996.