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Mode collapse

As explained in How Large Language Models Work

Mode collapse is a generative-model failure in which outputs become concentrated on a small set of common patterns while rare or diverse patterns are lost.

Mode collapse is a generative-model failure in which outputs increasingly favor the most common patterns in the training data while losing rare, nuanced, and interesting ones. A model may produce fluent results, yet represent less of the original variety. section 9.4.2

The failure develops through a feedback loop:

  • A generative model emphasizes the mode—the most common value or pattern in its training distribution. section 9.4.2
  • Rare or nuanced cases appear less often in generated output than they did in the original data. section 9.4.2
  • Training another model on that output reinforces the common patterns and removes more of the distribution’s variety. section 9.4.2
  • After enough repetitions, the model can become uselessly repetitive, producing nearly the same kind of output. section 9.4.2

A shrinking recipe collection

Imagine a recipe collection containing familiar dishes and a few unusual regional recipes. A model trained on it favors the familiar dishes. If its generated recipes become the next model’s training data, the unusual recipes become still less visible until the collection effectively contains only common dishes. The same pattern can affect text or images when repeated generations replace more varied source data. section 9.4.2

How How Large Language Models Work covers it

How deep it goes
Explains the mode, distribution bias, and repeated-training mechanism, but does not provide prevention methods.
Examples
Uses common-versus-rare distribution patterns, repeated model outputs, and a nuclear-testing analogy for contaminated future data.
What you can do after
Evaluate how repeated use of generated data can reduce output diversity and distort future model training.
How it connects
Connects generative models with training data, data distributions, feedback loops, and ethical data contamination.

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This explainer was generated by Manning's knowledge graph from the text of How Large Language Models Work. The section links point to the parts of the book it draws on.