Therefore I am. I Think
We consider the question: when a large language reasoning model makes a choice, did it think first and then decide to, or decide first and then think? In this paper, we present evidence that detectable, early-encoded decisions shape chain-of-thought in reasoning models. Specifically, we show that a simple linear probe successfully decodes tool-calling decisions from pre-generation activations with very high confidence, and in some cases, even before a single reasoning token is produced. Activation steering supports this causally: perturbing the decision direction leads to inflated deliberation, and flips behavior in many examples (between 7 - 79% depending on model and benchmark). We also show through behavioral analysis that, when steering changes the decision, the chain-of-thought process often rationalizes the flip rather than resisting it. Together, these results suggest that reasoning models can encode action choices before they begin to deliberate in text.
69cf0aeae02fdd68b91b79f2
Esakkivel Esakkiraja
claimed_verified
2026-04-07T08:45:53.134Z
6333213e66b27c4ad195bbc7
/avatars/0f911fee8c173543a6e0cbd78a940676.svg
Esakkivel Esakkiraja
dotvignesh
user
dotvignesh
69cf0aeae02fdd68b91b79f3
Sai Rajeswar
69cf0aeae02fdd68b91b79f4
Denis Akhiyarov
69cf0aeae02fdd68b91b79f5
Rajagopal Venkatesaramani
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2026-04-03T09:08:07.017Z
66f896dc2ff10730c5bb4976
/avatars/82b6dcaaa7df407c02652bd41d38387f.svg
Rajagopal Venkat
rajagopalvenkat
user
rajagopalvenkat
Therefore I am. I Think
We consider the question: when a large language reasoning model makes a choice, did it think first and then decide to, or decide first and then think? In this paper, we present evidence that detectable, early-encoded decisions shape chain-of-thought in reasoning models. Specifically, we show that a simple linear probe successfully decodes tool-calling decisions from pre-generation activations with very high confidence, and in some cases, even before a single reasoning token is produced. Activation steering supports this causally: perturbing the decision direction leads to inflated deliberation, and flips behavior in many examples (between 7 - 79% depending on model and benchmark). We also show through behavioral analysis that, when steering changes the decision, the chain-of-thought process often rationalizes the flip rather than resisting it. Together, these results suggest that reasoning models can encode action choices before they begin to deliberate in text.
Reasoning models appear to encode action choices before beginning textual deliberation, as evidenced by early decision detection and activation steering effects.
chain-of-thought linear probe activation steering tool-calling decisions pre-generation activations deliberation behavioral analysis