Try not to picture a pink elephant.
The instruction immediately puts the forbidden image in your mind. Negative prompting can create a similar problem for language models: to interpret what not to produce, the model still has to process the unwanted concept.
Heavy restrictions such as “do not sound robotic,” “do not use jargon,” or “do not be wordy” fill the context with the very patterns the response should avoid.
The practical fix is to describe the target directly.
Tone
Instead of saying, “Do not sound robotic or overly formal,” ask for a warm, conversational, approachable tone.
Length
Instead of saying, “Do not write a long response,” specify a concise response or a concrete length.
Focus
Instead of banning competitor discussion, tell the model to focus exclusively on the product’s unique features.
Negative constraints can still be necessary for safety and hard boundaries. But for style and direction, a positive target gives the model a clearer path.
Before sending a prompt, ask: am I describing what to avoid, or showing the model where to go?