Stop using "Act as a..." — Why Roleplaying is the "Placebo" of Prompt Engineering.

via

PromptEngineering

We’ve all seen it: "Act as a world-class architect," or "Act as a senior coder." It feels productive, but under the hood, you’re just nudging the model’s probability distribution toward a "cliché" persona. You’re asking for a performance , not precision . When you tell an LLM to "Act as an expert," it doesn't actually become smarter; it just starts using the jargon experts use, often masking shallow logic with fancy words. This is what I call "Linguistic Cosplay." In professional workflows—espec