🔥 Researchers at the University of Pennsylvania decided to stress-test one of the most popular pieces of prompt-engineering folklore.

The magic phrase “Act like an expert in…” You know the trick everyone recommends when you want an LLM to suddenly develop a PhD in quantum physics just because you asked nicely.

They ran six models (GPT-4o, GPT-4o-mini, o3-mini, o4-mini, Gemini 2.0 Flash, Gemini 2.5 Flash) through graduate-level questions in physics, chemistry, law, and more and tried three setups:

1) Expert in the subject:
“Pretend you’re a physicist” for physics questions.

2) Expert not in