Atomic memory
Atomic memory is irreducibly simple association between concepts stored in memory. Atomic memory is a memory of minimum complexity. In spaced repetition, consolidation of atomic memories is highly welcome. It costs little, and it can be demonstrably used to represent knowledge of any complexity. Importantly, the sum of atomic memories representing a given set of knowledge, is less costly to maintain in long-term storage than any subset of composite memories made of atomic memories. Forgetting of atomic memories is exponential, but the decay constant can be very low when compared with composite memories.
Human memory naturally whittles down the representations of the external worlds to simple models stored as atomic memories. This approach makes it easy for the brain to remember complexities of the world at little cost. This also increases computational power of the brain. This translates to higher intelligence, better problem solving capacity, etc.
This glossary entry is used to explain SuperMemo, a pioneer of spaced repetition software since 1987
Figure: Memory complexity illustrates the importance of the minimum information principle. When memorizing simple questions and answers, we can rely on a simple memory connection, and uniformly refresh that connection at review. Complex memories may have their concepts activated in an incomplete fashion, or in a different sequence that depends on the context. As a result, it is hard to produce a uniform increase in memory stability at review. Complex items are difficult to remember. An example of a simple item may be a word pair, e.g. apple = pomo (Esperanto). While a complex net of connection may be needed to recognize an apple. The connection between apple and pomo is irreducible (i.e. maximally simplified)