Three types of memory are important to learning, "working memory", "short term memory" and "long term memory." All three types of memory are used in the processing of both verbal and non-verbal information.
One reads a sentence and holds on to it. Then the next and the next. By the end of the paragraph, he pulls together the meaning of the full paragraph. This is working memory. He continues to read the full chapter and study it. Information is retained long enough to take a test and do well. This is short-term memory. But, unless the information is reviewed and studied over a longer period of time, it is not retained. With more effort over time, the information might become part of a general body of knowledge. It is long-term memory. If there are deficits in any or all of these types of memory, the ability to store and retrieve information required to carry out tasks can be impaired.