Encodes opposition, concession, and contradictory relationships.
What It Does
Relation.Contrast neurons activate on contrastive or adversative relationships: explicit contrast markers ('but', 'however', 'whereas', 'on the other hand', 'despite'), concession constructions ('although X is true, Y is also true'), and implicit contradiction ('the policy aimed to reduce poverty; inequality grew'). They encode the tension or opposition between two propositions.
How It Behaves
Contrast neurons concentrate in the middle-to-late layers, where the full contrastive relationship between two clauses or propositions can be computed. They interact strongly with Boolean.Polarity neurons (contrast often involves polarity reversal) and Relation.Causal neurons (causal relationships can be contrasted). Contrast neurons are particularly active in argumentative and analytical text, where the model must hold two competing propositions simultaneously.
Research Example
In Gemma 9B, Relation.Contrast neurons activate on 'the treatment was effective but expensive' and 'the results were promising yet inconclusive' — both involve holding a positive and negative proposition in tension. Models that fail on nuanced tasks like 'what are the advantages and disadvantages of X?' often show Contrast neuron suppression during the disadvantage-generation phase, causing them to produce only one side of the contrast.