Sibling posts are correct -- the chain-of-thought is doing hidden computation, it has been shown in the linked papers.

If you want to see it yourself: load up Qwen 3.8 in LM Studio and watch the CoT stumble around like a drunken sailor before miraculously jumping to the correct result.

If you want an example of subversion, Anthropic has some good ones:

https://transformer-circuits.pub/2025/attribution-graphs/bio...

https://transformer-circuits.pub/2025/attribution-graphs/bio...