IDEA 2004 continues to define specific learning disability as "a disorder in 1 or more of the basic psychological processes involved in understanding or in using language, spoken, or written, which disorder may manifest itself in the imperfect ability to listen, think, speak, write, spell, or do mathematical calculations." The term includes "conditions such as perceptual disabilities, brain injury, minimal brain dysfunction, dyslexia, and developmental aphasia." The term does not include "a learning problem that is primarily the result of visual, hearing, or motor disabilities, of mental retardation, of emotional disturbance, or of environmental, cultural or economic disadvantage."