Human-in-the-loopHITL

A setup in which an automated system, such as an AI agent, needs a person's decision or approval before it completes certain actions.

For example, a shopping agent may fill a cart on its own but wait for the person to approve the payment, or a fraud system may send an unclear identity check to a human analyst to decide.

A control design in which a human reviews, approves, or overrides an automated system's output at defined points before that output takes effect. Human-in-the-loop (HITL) is one point on a wider scale that describes how much a system may do without a person:

• Human-in-the-loop, where the action cannot complete until a person approves it, as when a payment over a set amount waits for confirmation.
• Human-on-the-loop, where the system acts on its own while a person monitors it and can pause it or reverse an action.
• Human-out-of-the-loop, where the system acts with no human involvement, and people review results only afterward, if at all.

Teams usually place the human according to risk:

1. The system scores each action by risk, using factors such as amount, type of action, and model confidence.
2. Low-risk actions inside a preset limit proceed automatically.
3. Actions above a threshold, or outside what the agent is permitted to do, pause for a person to approve or decline.
4. The decision and the evidence behind it are recorded for audit.

Some laws require human oversight. One example is Article 14 of the European Union's Artificial Intelligence Act (EU AI Act), which requires high-risk AI systems to let people understand their limits, override or reverse their decisions, and stop them. For remote biometric identification, it generally requires two qualified people to separately confirm a match before anyone acts on it.

Human-in-the-loop sits next to terms that are easy to mix up:

• Manual review is the human review of identity cases the system could not decide, one common form of human-in-the-loop.
• Agent mandate sets what an agent may do alone, and human approval covers what falls outside it.