Multi-Layer Sparse Autoencoders (MLSAE)

[!NOTE] This repository accompanies the preprint Residual Stream Analysis with Multi-Layer SAEs (https://arxiv.org/abs/2409.04185). See References for related work.

Pretrained MLSAEs

We define two types of model: plain PyTorch MLSAE modules, which are relatively small; and PyTorch Lightning MLSAETransformer modules, which include the underlying transformer. HuggingFace collections for both are here:

• Multi-Layer Sparse Autoencoders
• Multi-Layer Sparse Autoencoders with Transformers

We assume that pretrained MLSAEs have repo_ids with this naming convention:

• tim-lawson/mlsae-pythia-70m-deduped-x{expansion_factor}-k{k}
• tim-lawson/mlsae-pythia-70m-deduped-x{expansion_factor}-k{k}-tfm

The Weights & Biases project for the paper is here.

Installation

Install Python dependencies with Poetry:

bash poetry env use 3.12 poetry install

Install Python dependencies with pip:

bash python -m venv .venv source .venv/bin/activate pip install -r requirements.txt

Install Node.js dependencies:

bash cd app npm install

Training

Train a single MLSAE:

bash python train.py --help python train.py --model_name EleutherAI/pythia-70m-deduped --expansion_factor 64 -k 32

Analysis

Test a single pretrained MLSAE:

[!WARNING] We assume that the test split of monology/pile-uncopyrighted is already downloaded and stored in data/test.jsonl.zst.

bash python test.py --help python test.py --model_name EleutherAI/pythia-70m-deduped --expansion_factor 64 -k 32

Compute the distributions of latent activations over layers for a single pretrained MLSAE (HuggingFace datasets):

bash python -m mlsae.analysis.dists --help python -m mlsae.analysis.dists --repo_id tim-lawson/mlsae-pythia-70m-deduped-x64-k32-tfm --max_tokens 100_000_000

Compute the maximally activating examples for each combination of latent and layer for a single pretrained MLSAE (HuggingFace datasets):

bash python -m mlsae.analysis.examples --help python -m mlsae.analysis.examples --repo_id tim-lawson/mlsae-pythia-70m-deduped-x64-k32-tfm --max_tokens 1_000_000

Interactive visualizations

Run the interactive web application for a single pretrained MLSAE:

```bash python -m mlsae.api --help python -m mlsae.api --repo_id tim-lawson/mlsae-pythia-70m-deduped-x64-k32-tfm

cd app npm run dev ```

Navigate to http://localhost:3000, enter a prompt, and click 'Submit'.

Alternatively, navigate to http://localhost:3000/prompt/foobar.

Figures

Compute the mean cosine similarities between residual stream activation vectors at adjacent layers of a single pretrained transformer:

bash python figures/resid_cos_sim.py --help python figures/resid_cos_sim.py --model_name EleutherAI/pythia-70m-deduped

Save heatmaps of the distributions of latent activations over layers for multiple pretrained MLSAEs:

bash python figures/dists_heatmaps.py --help python figures/dists_heatmaps.py --expansion_factor 32 64 128 -k 16 32 64

Save a CSV of the mean standard deviations of the distributions of latent activations over layers for multiple pretrained MLSAEs:

bash python figures/dists_layer_std.py --help python figures/dists_layer_std.py --expansion_factor 32 64 128 -k 16 32 64

Save heatmaps of the maximum latent activations for a given prompt and multiple pretrained MLSAEs:

bash python figures/prompt_heatmaps.py --help python figures/prompt_heatmaps.py --expansion_factor 32 64 128 -k 16 32 64

Save a CSV of the Mean Max Cosine Similarity (MMCS) for multiple pretrained MLSAEs:

bash python figures/mmcs.py --help python figures/mmcs.py --expansion_factor 32 64 128 -k 16 32 64

References

Code

• https://github.com/openai/sparse_autoencoder
• https://github.com/EleutherAI/sae
• https://github.com/ai-safety-foundation/sparse_autoencoder
• https://github.com/callummcdougall/sae_vis

Papers

• Gao et al. [2024] https://cdn.openai.com/papers/sparse-autoencoders.pdf
• Bricken et al. [2023] https://transformer-circuits.pub/2023/monosemantic-features/index.html