← Lessons

quiz vs the machine

Silver1100

Machine Learning

Episodic vs Semantic Memory

Two kinds of agent memory and when each one matters.

4 min read · intro · beat Silver to climb

Two flavors of memory

Agent memory borrows two ideas from cognitive science. Episodic memory records specific events, what happened and when. Semantic memory stores general facts and learned knowledge, stripped of the moment they were learned.

Telling them apart

  • Episodic the user asked to cancel order 482 yesterday at noon
  • Semantic this user prefers email over phone, orders ship in three days
  • Episodic is a log of events, semantic is distilled knowledge
  • Episodes can be summarized into semantic facts over time

How they connect

Repeated episodes get distilled into stable semantic facts. The agent reads episodic memory to recall a specific past interaction and semantic memory to apply general knowledge.

Why the split helps

Keeping them separate lets the agent answer what did I do last time using episodes, and what is generally true using semantic facts. Mixing them makes both noisier and harder to retrieve.

Key idea

Episodic memory logs specific events while semantic memory holds distilled facts, and good agents convert recurring episodes into durable semantic knowledge.

Check yourself

Answer to earn rating on the learn ladder.

1. What does episodic memory store?

2. How do episodic and semantic memory relate over time?