Amnesia is the technical term for memory loss. Retrograde amnesia and anterograde amnesia are two common divisions of memory loss. However, memory and task performance are closely related. Memory for skills (procedural) and that for facts (declarative) may be affected in different ways. A person can loose the ability to write for a number of reasons, from disruption of the mechanics of motor control to inability to formulate language to express meaning. Language disturbances can make it difficult to separate pure memory disturbances from disturbances in comprehension.

Research indicates there may be many different memory “systems”, possibly dozens. Examples include differences in learning intentional and unintentionally - the former may be disrupted while the latter remains unaffected. It may be quite incorrect to think of “only” working memory and LTM.

A person may be completely unable to remember something that happened five minutes ago, but can remember how to write, ride a bicycle and do all other life activities, including writing down things in a diary to compensate for the memory loss.

Much remains unclear about memory structure and function.

Summary: We have a poor understanding of how memory is organized and functions.