Memory complexity

From supermemo.guru
Revision as of 19:14, 20 March 2018 by Woz (talk | contribs)
Jump to navigation Jump to search

Complexity of memory reflects the structural complexity of the neural network underlying a memory.

Simple memories may rely on a single connection that can be re-activated uniformly. Complex memories may involve a tangle of connections between a set of concepts that may be activated in a different sequence or constellation depending on the memory retrieval context.

Memory complexity correlates positively with:

  • number of synapses involved in retrieving a memory
  • difficulty in maintaining a memory in the long term (e.g. with SuperMemo)
  • difficulty in increasing memory stability with review (at comparable levels of retrievability)

Complex memories are hard to retrieve uniformly. For that reason, students should employ the minimum information principle. Simple memories are easier to recall, and are easier to store in long-term memory. In SuperMemo, complexity is represented by item difficulty.

The same item may be encoded differently by different users (e.g. depending on mnemonic skills). This means that memory complexity is a neural network property, not a direct reflection of semantic properties of the item.

Moreover, item difficulty is student-dependent. This means that even if two students encoded the same item with the same complexity, the item difficulties measured by the spaced repetition algorithm may differ (e.g. when one of the students tends to work in the morning, while the other chooses the evening).

An atomic memory is the simplest possible memory, which follows perfectly exponential forgetting, and perfectly complies with the two component model of memory.

Memory complexity is the third component in the three component model of memory that extends the two component model from atomic memories to complex memories.

This glossary entry is used to explain "I would never send my kids to school" (2017-2024) by Piotr Wozniak

Memory complexity: simple and complex memories

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)