Encodes currency values, prices, and financial quantities.
What It Does
Number.Money neurons constitute one of the most distinctive findings in our research: financial quantities have their own specialized neuron cluster, separate from general numerical processing. They activate on currency symbols ('$', '€', '¥'), monetary expressions ('five hundred dollars', 'a billion euros'), price contexts ('costs', 'worth', 'valued at'), and financial magnitude ('affordable', 'expensive', 'priceless').
How It Behaves
The existence of dedicated Money neurons reflects the volume of financial content in training data — economics, commerce, and pricing information is pervasive in the text corpora used to train modern language models. Money neurons concentrate in the middle layers and co-activate with both Number.Cardinal (for the amount) and Identity.Organization (for the entity being valued or paying). Their distinct signature from general Number neurons suggests the model has learned that monetary quantities require specialized handling.
Research Example
In Mistral 7B, Number.Money neurons distinguish between 'a million cells' and 'a million dollars' — the same numeral activates different neuron sub-types depending on whether a currency context is present. This specialization means that errors in financial reasoning (e.g., confusing millions and billions in cost estimates) have a Money-specific neuron signature distinct from general magnitude errors.