One such difficulty was its belief of central nervous system dysfunction as a basis of understanding and diagnosing learning disability. This conflicted with the fact that many individuals who experienced central nervous system dysfunction, such as those with cerebral palsy, did not experience disabilities in learning. On the other hand, those individuals who experienced multiple handicapping conditions along with learning disability frequently received inappropriate assessment, planning, and instruction. The NJCLD notes that it is possible for learning disability to occur simultaneously with other handicapping conditions, however, the two should not be directly linked together or confused. In the 1980s, NJCLD, therefore, defined the term learning disability as: a heterogeneous group of disorders manifested by significant difficulties in the acquisition and use of listening, speaking, reading, writing, reasoning or mathematical abilities. These disorders are intrinsic to the individual and presumed to be due to Central Nervous System Dysfunction. Even though a learning disability may occur concomitantly with other handicapping conditions (e.g. sensory impairment, intellectual disability, social and emotional disturbance) or environmental influences (e.g. cultural differences, insufficient/inappropriate instruction, psychogenic factors) it is not the direct result of those conditions or influences. The 2002 LD Roundtable produced the following definition:Concept of LD: Strong converging evidence supports the validity of the concept of specific learning disabilities (SLD). This evidence is particularly impressive because it converges across different indicators and methodologies. The central concept of SLD involves disorders of learning and cognition that are intrinsic to the individual.
While some attribute the disproportionate identification of racial/ethnic minorities to racist practices or cultural misunderstanding, others have argued that racial/ethnic minorities are overidentified because of their lower status. Similarities were noted between the behaviors of "brain-injured" and lower class students as early as the 1960s. The distinction between race/ethnicity and SES is important to the extent that these considerations contribute to the provision of services to children in need. While many studies have considered only one characteristic of the student at a time, or used district- or school-level data to examine this issue, more recent studies have used large national student-level datasets and sophisticated methodology to find that the disproportionate identification of African American students with learning disabilities can be attributed to their average lower SES, while the disproportionate identification of Latino youth seems to be attributable to difficulties in distinguishing between linguistic proficiency and learning ability. Although the contributing factors are complicated and interrelated, it is possible to discern which factors really drive disproportionate identification by considering a multitude of student characteristics simultaneously. For instance, if high SES minorities have rates of identification that are similar to the rates among high SES Whites, and low SES minorities have rates of identification that are similar to the rates among low SES Whites, we can know that the seemingly higher rates of identification among minorities result from their greater likelihood to have low SES.