Parents often say that their learning-disabled child frequently bangs into objects, knocks things over and is awkward. Perception is the interpretation of information that comes to us from our environment. Most information is not strictly visual or auditory, but rather a combination of the two. Students with learning disabilities have difficulty with different components of perception. Many other students with learning disabilities have other problems related to attention.
ADD refers to a specific group of students who have difficulty concentrating on a task.
They may or may not be hyperactive. For example, they may have difficulty staying on a task, deciding what is important and what is not in a lecture or reading passage, and they may not be able to sustain attention for particular tasks. Some students who have learning disabilities have difficulty with memory. If you don't pay attention or attend to the information coming in from the environment you'll never get it into your short-term memory. Clearly, that is exactly what happens to many students with learning disabilities.