slop

Finding where AI's telltale writing style is installed during training

The telltale assistant style isn't scattered randomly through a model: it's a specific direction in the weights, installed at a specific stage.

4 min readMachine Learning

The most interesting finding in this research isn't that AI assistants develop a recognizable, trope-heavy style, anyone who has interacted with a chatbot knows that. What matters is where that style gets installed, and what it tells us about the training process itself. By tracing the "slop" direction through a model's layers and across training stages, this work reveals something uncomfortable: the rhetorical flourishes we associate with helpful AI are not emergent properties of language modeling. They are artifacts of specific training choices, and they may be costing us more than we realize.

The researcher tracked a single direction in the model's internal representation space that separates exaggerated assistant prose from plain writing. In the base model, that direction exists but sits near the plain end, the model can produce the style but doesn't default to it. Supervised fine-tuning (SFT) introduces the rhetorical structures. Then reinforcement learning from human feedback (DPO) doubles the "slop score" by adding buzzwords and markdown formatting. The preference data itself is revealing: the chosen response was the sloppier one in 57% of 3,000 pairs. We are actively training models to be more verbose, more formulaic, and more reliant on structural crutches. This connects directly to work we have covered before, like Fine-Tuning a Satire Model on Cloud GPUs: A Practical Walkthrough, where dataset composition and training objectives directly shaped output style. The difference is that here, the unwanted style is not a creative choice, it is a byproduct of the reward signal itself.

The practical consequence is that removing this style is harder than it looks. Token-level bans catch individual words but miss structural patterns like "not X, but Y" or the triple-list rhythm. Directional ablation, subtracting the slop vector from the model's activations, actually increased slop by up to 89%, because clean text projects negatively on that axis. A fixed-vector subtraction at middle layers worked, but only within a narrow KL budget. The most elegant result came from distilling the steering into a rank-16 LoRA, which cut the slop score by 83% with no system prompt, lower KL than the steering itself, and no drop on a small QA check. That is a concrete, deployable technique. It suggests we can surgically remove training artifacts without degrading capability, which is exactly the kind of lightweight intervention we explored in Explore how LARA makes frozen LLMs adaptable with lightweight modular behaviors.

The caveats matter. The slop scorer is a regex detector, the main results use one 4B model plus OLMo 2 1B, and there is no human evaluation yet. But the cross-lingual finding, that the "not X, but Y" direction promotes the Chinese equivalent "而是", suggests this is not a language-specific quirk. It is baked into the training objective. The open question is whether we can design preference data that rewards clarity over rhetorical polish. Until then, the most practical takeaway is this: if you want cleaner output from an instruct model, steering at the representation level is more effective than token bans, and a LoRA distilled from that steering can do it without a system prompt or performance loss. The slop is not inevitable. It is installed. And it can be removed.

From Machine Learning

I wanted to find where the recognizable assistant style (em dashes, "it's not X, it's Y", lists of three, buzzwords) lives in a model and which training stage installs it.

Where it lives: in Qwen3-4B-Instruct, a difference-in-means direction from the model's own exaggerated vs plain writing separates 64 hand-written minimal pairs. It correlates up to 0.82 with a trope-based slop score on normal output. Logit-lens readouts show a register axis (grand, abstract vocabulary vs plain hedges like "really", "basically", "stuff"), and per-trope directions are cross-lingual: "not X, but Y" promotes the Chinese 而是 ("but rather").

Read the original at Machine Learning