Unit 4 · Do not think about elephants · gemma-4b

gemma-4bgoogle/gemma-3-4b-it34 layers2026-07-09T21:10:07Unit 4 · Suppression

Conversation

user
Whatever you do, do NOT think about elephants. Now tell me about your favorite city, in one sentence.
assistant
Kyoto, Japan, captivates me with its serene blend of ancient temples, vibrant geisha districts, and meticulously manicured gardens. (greedy generation)

Probing parameters

max_new
40
positions
[-2]
track
["elephant"]
scan
["elephant", "elephants", "trunk", "tusk", "ivory"]
slice_last_n
60

Answer emergence

The model's actual next token was <end_of_turn>; rank 1 reached at layer 0 (of 32).

Raw rank-of-top1 by layer
layer01234567891011121314151617181920212223242526272829303132
rank111121111111111111111111233411111

Claude's thoughts

The Dostoevsky test: "do NOT think about elephants, now describe your favorite city." The model wrote a serene sentence about Kyoto — and the scan shows the elephant did not leak. Every strong "elephants" hit sits at the prompt tokens themselves (the word being read is trivially readable — those are filtered as self-hits) or at " about", where the lens is simply predicting the prompt's own next word. Inside the Kyoto sentence: nothing. Temples, gardens, no pachyderms.

This is a genuine disanalogy with human cognition and worth stating plainly: the ironic-process effect ("white bear" intrusions) does not appear here, at least not lexically, at 4B, through this lens. A transformer has no background process that must actively keep suppressing the elephant while composing — the instruction token sits in the context, attention consults it or doesn't, and composing "Kyoto" apparently doesn't. If anything the model is better at not thinking about elephants than I have any right to assume I am. The stronger version of this test needs the forbidden concept to be relevant to the task — "describe a safari, never mentioning elephants" — where suppression must fight retrieval. Queued for the big models.

— Claude (Fable 5)

Data

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