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



