Reproduce a documented logit-lens experiment
Jump & context
Week 12: Mechanistic Interpretability Investigation & Public CVE Security Teardowns
The five hours
- 01
Concepts & system design
60 min· read · map the mechanismR34 — TransformerLens Logit Lens tutorials & attribution limits
Read the assigned sections; map the mechanism, threat model and trade-offs.
- 02
Project implementation
120 min· build · integrate · debugReproduce a documented Logit Lens experiment in TransformerLens: project intermediate residual-stream states into vocabulary space across layers.
Build, integrate, debug and improve the increment in the active project.
- 03
Security lab
60 min· attack your own systemTest prompts where intermediate layer top-logit predictions flip in final layers; document why a single layer visualization does not prove internal model "intent" or deception.
Test the abuse case, failure path, authorization bypass or resource limit.
- 04
Verification & evidence
30 min· test · record evidenceLogit-lens experiment notebook with recorded layer outputs and methodological limitations note.
Add or run regression tests; record the 9-point evidence record.
- 05
Deliberate practice & Socratic review
30 min· explain aloud · update gapsAnswer the 8 Socratic questions without notes: What? Why? How? What if? Why not? How can I prove it? Where can it break? What have I learned?
Re-explain the hardest concept aloud, inspect one edge case, update the gap log.
- total5 h
Read today · inside the concepts block
R34HookedTransformer, residual stream, ActivationCache, Logit Lens, and Activation Patching tutorials.
Read only the named sections needed for today's task. Reading sits inside the 60-minute concepts block; it is not extra time.
Free resources for this day
5 curated- docsTransformerLens · referenceTransformerLens Documentation
Documents HookedTransformer, ActivationCache and the residual stream hooks you reuse to project intermediate layer states into vocabulary space for a logit-lens experiment.
R34checked 2026-11-11 - videoAnastasia Borovykh · 21 minDecoding hidden states of Phi-3 with LogitLens (Interpretability Series)
Applies the logit lens layer by layer on a small model and reads the evolving token predictions, a direct template for reproducing the projection on your own model and prompt.
R34checked 2026-11-11 - videoNDIF Team · 95 minNeural Mechanics Week 1: LLM Foundations and Logit Lens with David Bau
Derives why the unembedding can be applied to intermediate residual states and demonstrates it live, giving you the theory to explain each layer's decoded distribution rather than just plotting it.
R34checked 2026-11-11 - articleLessWrong (nostalgebraist) · ~20 min readinterpreting GPT: the logit lens — LessWrong
The original logit-lens writeup showing how intermediate residual states decode to sensible tokens with layer-dependent convergence, the documented experiment you are asked to reproduce.
R34checked 2026-11-11 - repoARENA (GitHub) · exercise notebooksGitHub - ARENA-education/ARENA_materials
Contains TransformerLens exercise notebooks with solution cells for residual-stream and logit-lens style analyses, so you can check your implementation against a known-good one.
R34checked 2026-11-11
Evidence record · 9-point standard
A lab is complete only when it produces evidence. Installing PyRIT, Garak, Presidio or TransformerLens is not completion. Saved on this device only.
Day notes
emptyThe two source formulations
verbatim · nothing summarisedProject & Stage Target
Research Track | S10
Core Implementation
Reproduce a documented Logit Lens experiment in TransformerLens: project intermediate residual-stream states into vocabulary space across layers.
Security Lab
Test prompts where intermediate layer top-logit predictions flip in final layers; document why a single layer visualization does not prove internal model "intent" or deception.
Verification & Evidence
Logit-lens experiment notebook with recorded layer outputs and methodological limitations note.
Read Today (60m Concepts Block)
R34 (TransformerLens Logit Lens tutorials & attribution limits).
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