MultiModal Reward

Reward function for evaluating multimodal visual question answering (VQA) tasks.

MultiModalAccuracyReward

Evaluates the correctness of multimodal VQA answers with a fallback to symbolic math verification.

from twinkle.reward import MultiModalAccuracyReward

reward_fn = MultiModalAccuracyReward()
rewards = reward_fn(generated_trajectories, ground_truth_trajectories)
# rewards: List[float], 1.0 for correct, 0.0 for incorrect

The reward function:

1. Extracts the model’s answer from the completion text

2. Compares with ground truth using exact string matching

3. Falls back to math_verify for symbolic expression comparison when string matching fails

Designed for visual reasoning tasks such as CLEVR, where answers may be numeric, boolean, or short text.