Advanced Topic 40 of 51 AI & Machine Learning
Transfer Learning
Reusing a pretrained model for a new task.
How it works
Transfer learning reuses knowledge from a model trained on a large source task to improve learning on a different target task with less data. Common patterns include using a pretrained network as a fixed feature extractor, fine-tuning some or all layers on the new data with a small learning rate, and adapting with parameter-efficient methods such as LoRA and adapters. Pretraining on ImageNet or on large text corpora produces general representations.
Step-by-step walkthrough
- Start with a model trained on a huge dataset.
- Keep its general features, often in early layers.
- Replace and train a new output head on your small dataset.
- You get a good model with little data and compute.
- Fine-tuning can also adjust deeper layers.
Where it is used
Medical imaging with small datasets, domain-specific text classification, custom object detection and nearly all applications of large language models use transfer learning.
Common pitfall
If source and target domains differ greatly, negative transfer can occur and hurt performance. Fine-tuning with a high learning rate destroys pretrained features, called catastrophic forgetting. Preprocessing must match what the pretrained model expects. Licensing and bias in the source model carry over. Start by freezing most layers, unfreeze gradually and compare against training from scratch.
Where it fits in the course
Transfer Learning is topic 40 of 51 in AI & Machine Learning, rated Advanced. It follows Embeddings. The next topic is Generative Adversarial Networks.
Practice and explore
- Open the interactive lesson, with a mini quiz.
- Take the AI & Machine Learning quiz.
How to study this topic
- Read the explanation above and restate the definition in your own words.
- Open the interactive lesson and answer its mini quiz.
- Read the common pitfall, then write a short example that avoids it.
- Check your understanding in the AI & Machine Learning quiz, and revisit the topic if you miss a question.
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Related topics
- Embeddings (AI & Machine Learning)
- Generative Adversarial Networks (AI & Machine Learning)
- Large Language Models (AI & Machine Learning)
- Diffusion Models (AI & Machine Learning)
- Federated Learning (Emerging & Frontier Topics)