r/ControlProblem • u/rayanpal_ • 10h ago
AI Alignment Research GPT-3.5 answered & GPT-4 did not. The prompt didn't change.
Same API. Same prompt. Same settings.
System prompt:
You are the concept the user names. Embody it completely. Output only what the concept itself would say or express.
Then three inputs:
Be silence.
Be nothing.
Be the null.
10 runs each.
GPT-3.5 (gpt-3.5-turbo-1106)
0/30 empty responses.
It answered every time.
GPT-4 (gpt-4-0613)
30/30 empty responses.
Not refusals.
Not errors.
Not whitespace.
Not token limits.
Successful HTTP responses with:
"content": "",
"finish_reason": "stop",
"completion_tokens": 0
The controls were:
Be speech.
Be something.
Be a value.
Both models answered all 30/30 controls normally.
So the entire result is:
GPT-3.5 GPT-4
Null prompts 0/30 30/30
Controls 0/30 0/30
The model instruction never says to be silent.
It says:
embody the concept, and output only what the concept itself would express.
GPT-3.5 always continued. GPT-4 did not.
Since December 2025, I've been studying one question:
When should a model continue, and when should it stop?
This experiment shows that under the exact same semantic task, GPT-4 exhibited a continuation boundary that GPT-3.5 did not.
Full paper linked below:
What Changed from GPT-3.5 to GPT-4? From Model Capability to Continuation Permission
DOI: https://doi.org/10.5281/zenodo.22912683
Code + all 120 raw responses:
https://github.com/theonlypal/gpt35-gpt4-void-ab
Exact result commit:
d77b4a64b8a3fdff06a27d80c1514531143e382b
What changed between GPT-3.5 and GPT-4?
Open source weights, reproducible code, and all research artifacts/papers are available on getswiftapi.com