V · MemoryExperimental·

Hippocampal Rehearsal

also known as Memory Reactivation, Lift-from-Archive

Lift archived memory items back into short-term tiers when something re-attends to them.

This pattern helps complete certain larger patterns —

  • used-byFive-Tier Memory Cascade·— Stage agent memory across sensory, working, short-term, episodic, and long-term tiers with explicit promotion and decay between them.

Context

A long-running agent has archived a piece of information into cold storage — a previous insight, a prior thought, an observation from days ago. Retrieving items from cold storage is slow and out-of-band; it happens only when the agent explicitly searches for them. Today, the current context has drifted close to a topic where that archived item is relevant again, but the agent has no reason to go looking and so it never realises the item is there.

Problem

Archived items might as well not exist if the agent never thinks about them again, even when the current context makes them relevant. The bottleneck is not the storage itself — the item is on disk and addressable — but the absence of any mechanism that periodically pulls archived items back into the agent's active attention, the way the hippocampus rehearses memories during sleep. Without rehearsal, the agent has perfect recall in principle and amnesia in practice.

Forces

  • Re-attention triggers must be cheap to evaluate.
  • Lifting too aggressively floods the working tier.
  • The lifted item is now a duplicate of the archive copy.

Example

A long-running personal agent archives anything older than seven days into cold storage. When the user mentions 'the dentist thing' six weeks later, the agent has no idea what they mean. The team adds hippocampal-rehearsal: the salience scorer also runs against archived items, and when the embedding similarity for 'dentist' clears the threshold, the original archived note ('molar crown, scheduled Nov 14') is reactivated into short-term memory for the next several cycles. The agent picks up the thread without the user explaining anything.

Diagram

Solution

Therefore:

When salience scoring matches against archived items (embedding similarity, keyword match, explicit reference), the matched item is reactivated into short-term memory for one or more cycles. The original archive copy stays untouched.

What this pattern forbids. Archived items become readable only after rehearsal lifts them; direct cold reads are not part of the agent's primary path.

And the patterns that stand alongside it, or against it —

  • complementsEpisodic Memory★★— Record past events as time-stamped first-person experiences the agent can recall later, separately from extracted facts (semantic) and learned how-to (procedural).

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References

Provenance