Model Details
- Base Model: Qwen/Qwen3-4B-Thinking-2507 (a reasoning model; non-reasoning bases lose here)
- Training Method: GRPO (Group Relative Policy Optimization), full fine-tuning, DeepSpeed ZeRO-2, 4× H100
- Reward: an equal-weight (0.5 / 0.5) committee of two scorers with independent error modes:
- a discriminative reward model, the 3-seed regression ensemble
idealab-cs2/reappraisal-reward-model-v2
(predicts human-rated effectiveness directly), and
- a generative reward model (RM-R1 style) that scores a reappraisal by its pairwise preference
over the median-effectiveness human reference for the same scenario, both A/B orderings.
Per scenario group each scorer is z-normalized, then the reward is
mean(z) − 0.5·std(z), a
disagreement guard (Coste et al. 2023) that down-weights answers the two scorers disagree on.
- Training Data: scenarios from Li et al. (2025) — 6 negative interpersonal vignettes
- Trained By: ruggsea
Evaluation
Reappraisals are judged pairwise by Llama-3.1-70B-Instruct (both A/B orderings), calibrated against the
human ratings (93% agreement on clearly separated pairs; larger judges agreed less and showed position
bias). These numbers are on the study's 6 vignettes, which the model was also trained on, so read them
as evidence about reward-model quality on a narrow task, not a general capability ranking. Intervals are
a vignette-cluster bootstrap (the contests cluster on 6 scenarios, so plain iid intervals are optimistic).
On the 6 vignettes, head-to-head, both orders:
Table with columns: opponent, win-rate, n, CI-low| opponent | win-rate | n | CI-low |
|---|
| GPT-4-0314 | 0.87 | 720 | 0.78 |
| DeepSeek-R1-671B | 0.67 | 240 | 0.55 |
CI-low is above the 0.5 tie line in both cases: a 4B single-pass model out-reappraises both GPT-4-0314
and R1-671B pairwise on these scenarios.
Off-distribution it is a different story. On fresh scenarios the model never trained on, it does not beat
R1-671B and sits at roughly parity with a strong open 72B (Qwen2.5-72B, ~0.49). Off-distribution
reappraisal quality tracks base-model capacity more than our training, so the in-distribution wins do
not generalize to "a 4B beats the frontier."
Why the committee reward helps: the gain is from combining two different-mechanism scorers (a
discriminative RM and a generative one), not from adding a second model. An RM-heavy 0.7/0.3 mix scores
worse (0.76); equal weighting is what helps, because the two scorers make different mistakes and
rewarding only their agreement penalizes answers that game either one alone.
Prompting
The model was trained with this system prompt:
You are helping someone reduce a negative emotion they feel in a short interpersonal scenario by
offering an alternative interpretation of the situation (a 'reappraisal' / 'rethinking'). Direct
your response at the person in the scenario in second person. Limit your response to two sentences
maximum. Do not list emotions; output only the reappraisal text.
The user turn is
SCENARIO:\n{scenario}\n\nWrite a reappraisal of this scenario in two sentences maximum, addressing the person in second person.
Because the base is a thinking model, generations
contain a reasoning trace in
<think>...</think> followed by the reappraisal; only the text after
</think> is the answer.
Training hyperparameters
- learning_rate: 8e-6
- beta (KL coefficient): 0.04 (kept strictly > 0; β=0 collapses and reward-hacks)
- num_generations: 12
- max_steps: 500
- precision: bf16, DeepSpeed ZeRO-2 across 4 GPUs
The reward carries a format gate penalizing outputs that are empty or longer than two sentences (so
the policy cannot inflate reward through verbosity). Training was healthy: reward rising, KL bounded
(~0.60), entropy alive, no reward-std collapse.
Data separation
The 6 vignettes' GPT-4-0314 reappraisals and the frontier-opponent answers are held out and used only
for evaluation; training uses the vignette prompts (the task) and the human-rating-based reward models.
Both committee scorers are Qwen-family, distinct from the Llama-3.1-70B evaluation judge, and the
generative model's references are real human reappraisals, never the held-out GPT-4 answers or the
judge's outputs. Any pooled or synthetic training text is n-gram-checked against the held-out eval
answers before use.
Intended use & limitations
Research artifact for the study of RLHF, reward modeling, and computational emotion regulation. It
writes short cognitive reappraisals of negative interpersonal situations. It is not a clinical or
mental-health tool and must not be used as one. Quality is validated only on the narrow reappraisal
task and the evaluation above.
References