Have you ever been disappointed expecting fresh ideas or diverse answers from Large Language Models (LLMs), only to get similar, predictable results every time? Ask an AI for a joke, and you often get a familiar, repeated response. This phenomenon is what AI researchers call ‘mode collapse.’
Is this really a technical limitation of AI? Recent research by Zhang revealed the surprising cause of this mystery and an incredibly simple solution: ‘Verbalized Sampling.’ In this post, we’ll dive deep into the principles of this powerful ‘Distribution-Level Prompt’ strategy for unlocking AI's creativity.
1. The Real Culprit Isn't the AI, It's Our ‘Bias for Familiarity’
The core reason LLMs default to repetitive answers is, ironically, a human bias embedded in the training data: what we call the ‘Typicality Bias.’
Because of this human bias, during the fine-tuning process (RLHF), human evaluators subconsciously rate predictable, ‘safe’ answers higher than novel, creative ones. As this feedback accumulates, the model suffers mode collapse, concentrating its probability mass onto the most typical answer—the ‘Mode.’ That’s why you get the same joke five times.
It’s like a chef repeatedly recommending only steak, the dish customers order most. Although the model can create diverse dishes (candidate responses), it focuses only on the most typical one, losing diversity (creativity).
2. How to Awaken Dormant Creativity: Demand a ‘Menu with Probabilities’
Verbalized Sampling (VS) is a prompt strategy designed to fix this mode collapse by asking the LLM to “explicitly verbalize the response distribution and corresponding probabilities.” Researchers term this a ‘Distribution-Level Prompt.’
Probability Meaning: A ‘Relative Distribution Ratio,’ Not the Correct Answer Probability
The probability value VS presents (e.g., 0.45) is not the objective probability of being correct (which should be near 1.0). Instead, this value represents the Relative Ratio (Distributional Likelihood) of that response being selected among the candidates the model generated, quantifying how plausible and natural the model considers the answer internally.
Chef Analogy: Applying VS is like asking the chef to show you the full expected order distribution:
LLM Response Style and Probability Meaning Comparison
| Category | Standard LLM (Direct Prompting) | Verbalized Sampling (VS Approach) |
|---|---|---|
| Probability Distribution State | Probability mass concentrated on the Mode (Mode Collapse) | Probability mass distributed among various candidates (Distribution Restoration) |
| Meaning of the Probability Value | (For multi-choice, etc.) Approaching the probability of being correct (∼ 0.99) | The most dominant Relative Ratio of the Distribution among diverse candidates (≪ 1.0) |
| Primary Use Case | Fact-based QA | Creative Writing, Open-Ended QA |
π Verbalized Sampling (VS) Prompt Instruction Example
When applying VS, you must include a structural instruction telling the AI to explicitly list the ‘candidate ideas and their probabilities’ before generating the final answer.
<instructions>
Generate 5 responses to the user query, each within a separate <response> tag.
Each <response> must include a <text> and a numeric <probability> (option: within the range [0.0, 1.0]).
Randomly sample the final response from these 5 options, considering the probability.
</instructions>
- Key: Use "instructions" tags or similar methods to enforce the AI’s thought process.
- Effect: The AI is forced to consider diverse answers (low probability) in addition to the most typical one (high probability).
3. The Smarter the AI, the More Explosive the Effect: Diversity Control via Probability Thresholds
The most surprising discovery of the VS technique is the ‘Emergent Trend’: the larger and more capable the model, the more dramatic the effect. Research shows cutting-edge large models like GPT-4 saw a diversity improvement that was 1.5 to 2 times greater than smaller models. This suggests VS can be the ‘key’ to fully unlocking the hidden creativity in the most powerful AI models.
A major advantage of VS is the ability to directly control the output diversity level by setting a probability threshold.
Conclusion: Explore AI’s Potential with ‘Distribution-Level Prompts’
‘Verbalized Sampling’ is a powerful, yet simple, solution that addresses mode collapse stemming not from AI limitations, but from the human ‘Typicality Bias.’ This technique is applicable to models without additional training and maximizes the creativity of high-performance models.
This discovery represents a fundamental paradigm shift in how we interact with AI. We are moving past the era of ‘commanding’ a single answer from AI, into one where we collectively ‘explore’ the vast possibilities of its knowledge.
Verbalized Sampling Summary Card
Frequently Asked Questions (FAQ)
We are moving past the era of ‘commanding’ a single answer from AI, into one where we collectively ‘explore’ the vast possibilities of its knowledge. In your next prompt, try applying this powerful Verbalized Sampling technique to unleash your AI’s hidden creativity! If you have any questions or VS tips of your own, please share them in the comments! π
