in this chapter, however, is on the known processing deficits experienced by those with learning, reading, and writing disabilities about which there is broader agreement.
Learning disabilities in adulthood by definition describe individuals as developmentally disordered in learning in comparison to age-expected performance and appropriate instructional opportunities. A diagnosis requires evidence that an individual is substantially limited in major life activities (e.g., reading or writing). If learning disabilities are not diagnosed before adulthood, however, it may be difficult to establish that the individual had access to sufficient high-quality instruction. Social/emotional, cognitive, oral language, and achievement abilities influence individual learning differently across the life span, and the recognition of age-specific markers may be critical to reliable and valid diagnostic decision making appropriate for the adolescent and adult population (Gregg, 2009). Adults can experience a range of learning disabilities that are important to diagnose and attend to as part of literacy instruction.
Although better information is needed about the number of adults in literacy programs with learning disabilities, over one-quarter of adults who attend adult education programs report having a learning disability (Tamassia et al., 2007). The prevalence of learning disabilities for the college-bound population is reported to be approximately 3 to 5 percent of student enrollment (National Center for Education Statistics, 2009; Wagner et al., 2005). Due to variability in eligibility criteria, the adult population with learning disabilities represents a very heterogeneous group of individuals in terms of severity, ability, and background.
Many individuals with learning disabilities do not have access to opportunities to develop and demonstrate their knowledge, with unsettling consequences for their career development and adult income (Gregg, 2009; Rojewski and Gregg, 2011). A total of 14 million undergraduates are enrolled in 2- and 4-year colleges in the United States, and the number is expected to reach 16 million by 2015. Among the U.S. population with learning disabilities, approximately 17 percent will take college entrance
low average intelligence, intact sensory abilities, and adequate instructional opportunities. Recent research findings, however, have a greater focus on other approaches such as response to intervention or differentiated diagnoses based on learning over time (Burns, Appleton, and Stehouwer, 2005; Fletcher, Denton, and Francis, 2005; Fuchs and Fuchs, 2005). There is growing agreement among some researchers that a hybrid model of identification is necessary to the definition of learning disabilities, which includes three criteria: (1) inadequate response to appropriate quality instruction; (2) poor achievement in reading, mathematics, or written expression; and (3) evidence that other factors are not the primary cause of poor achievement (Bradley, Danielson, and Hallahan, 2002; Fletcher et al., 2007). At present, however, there is not conclusive evidence or consensus on any one diagnostic approach to identifying learning disabilities.