Definition
A common teaching framework, popularised by Arend Hintze, sorts AI into four types by how it functions: reactive machines, limited memory, theory of mind and self-aware AI. The first two exist, and the last two are still ideas.
In simple words
A reactive machine only sees the present, like a thermostat with no memory. Limited memory uses recent data, like a self-driving car watching nearby cars. Theory of mind would understand what people feel and want. Self-aware AI would know it exists. We've built the first two.
Why it matters
This list appears in many syllabi, exams and interviews. It's also useful for spotting hype: when a chatbot appears to have feelings, that's pattern-based text, and nothing shows it's self-aware.
How it works
| Type | How it works | Status | Example |
|---|---|---|---|
| Reactive | Responds only to the present input and stores no experience | Exists | IBM's Deep Blue chess computer |
| Limited memory | Uses past data, for training or for a short time | Exists: nearly all modern AI | Self-driving cars, chatbots |
| Theory of mind | Would model other minds' beliefs and emotions | Research only | None established |
| Self-aware | Would have consciousness and a sense of self | Hypothetical | None |
Try it yourself
How much can it remember and understand?
This is another way to group AI. Only the first two exist today.
Which type is it?
Sort each system by how it works with memory and minds.
A video app recommending based on what you watched
A self-driving car watching nearby cars
IBM's Deep Blue chess computer (1997)
A machine conscious of its own existence
A robot that truly understands your feelings and intentions
Common mistakes
- Thinking that a chatbot which says it has feelings really has them.
- Mixing up this list with narrow, general and super. Those measure capability, and this measures function.
Check yourself
Summary
- Four types: reactive, limited memory, theory of mind, self-aware.
- Nearly all of today's AI is limited memory.
- It's a teaching framework, separate from narrow, general and super.
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