Decoder. plain-English AI glossary

Reward model training

● Core

Also called Reward Model Training

Teaching a separate model to predict which responses humans prefer, so it can score outputs during RL.

Think of it like

Training a judge by showing them thousands of pairs of dishes and which one diners liked, until they can score new plates.

Example

From a dataset of chosen-vs-rejected reply pairs, a model learns to output higher scores for the responses people picked.

How it actually works

The reward model is trained on human preference comparisons to output a scalar "how good is this" score. In RLHF, that score becomes the reward signal a policy optimizes against. Its quality caps the whole pipeline: if it is exploitable, the policy will reward-hack it, and if its preferences are biased or narrow, those flaws propagate into the final model. It usually starts from the base model itself.

For product teams

The stand-in for human judgment that scales preference feedback — and whose blind spots become the model's.

For engineers

Train a scalar scorer on pairwise human preferences; it provides the reward in RLHF and is a target for reward hacking.

Related

Read anything AI without the jargon

Look up any term in plain English, or save terms as you read with the free Chrome extension.

Open DecoderAdd to Chrome