Encodes periods, spans, and lengths of time.
What It Does
Time.Duration neurons activate on temporal span references: explicit durations ('for three hours', 'over a century', 'within 48 hours'), implicit period references ('a long time', 'briefly', 'momentarily'), and comparative duration ('longer than expected', 'shorter than the previous record'). They encode how long something lasted rather than when it occurred.
How It Behaves
Duration neurons show a strong early-layer concentration, suggesting that parsing temporal extent is an early processing operation that precedes contextual integration. They interact with Number neurons (durations are quantities) and Relation.PartWhole neurons (a duration is a portion of a larger timeline). Duration neurons are more active in technical, scientific, and procedural contexts where precise temporal spans matter.
Research Example
In Llama 3.1 8B, Time.Duration neurons activate differently on 'it took three days' (definite duration) vs. 'it took a while' (indefinite duration) — both trigger Duration neurons, but the indefinite case co-activates Entropy.Ambiguity neurons while the definite case co-activates Number.Cardinal neurons. This distinction is important for tasks requiring precise temporal reasoning.