Research map / Vision-language and multimodal / Human and embodied modeling
Measuring Dejavu Memorization Efficiently
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Proposes one-model déjà vu memorization tests that replace the second reference model with a ResNet50 or Naive Bayes classifier (image) or a GTE text-embedding nearest-neighbor reference (VLM), enabling memorization measurement of pre-trained open-source models without retraining.
Problem
Measuring déjà vu memorization in representation learning models normally requires training a second reference model on disjoint training splits, which is infeasible for large pre-trained open-source image and vision-language models.
Approach
Estimate dataset-level correlations with cheap reference predictors (a ResNet50 background-crop classifier, a Naive Bayes classifier over detected crop objects, or a pre-trained text embedding model with nearest-neighbor caption matching) so that memorization of an off-the-shelf model can be measured with a single model.
Key results
- On ImageNet, the one-model ResNet50 and Naive Bayes tests identify similar déjà vu memorization to the two-model KNN test for VICReg and Barlow Twins, with DINO showing substantially lower memorization.
- For a CLIP model trained on 40M Shutterstock pairs, the one-model GTE-based test gives 0.07 PPG and 0.06 PRG for top-10 objects with 10 NNs, versus 0.06 PPG and 0.06 PRG for the two-model test.
- Pre-trained open-source models (e.g., YFCC15M CLIP at 0.07 PPG and PRG) show lower aggregate memorization than the same models trained on subsets of the data.
Measured effects reported in the paper
| What was changed | Where | Measured | Effect |
|---|---|---|---|
| Replace the separately trained reference VLM with a GTE text-embedding reference | CLIP déjà vu memorization measurement on Shutterstock · Shutterstock, top-10 objects with 10 nearest neighbors | PPG: 0.06 -> 0.07 | Mixed |
| Replace the separately trained reference VLM with a GTE text-embedding reference | CLIP déjà vu memorization measurement on Shutterstock · Shutterstock, top-10 objects with 10 nearest neighbors | PRG: 0.06 -> 0.06 | No clear effect |
| Increase the number of crop-annotation features in the Naive Bayes reference (ablation) | ImageNet image representation memorization measurement · ImageNet | déjà vu score | Hurt |
| Use open-source pretrained models rather than the same models trained on a smaller subset | VICReg, Barlow Twins, and DINO · ImageNet | déjà vu memorization | Hurt |
| Use VICReg or Barlow Twins rather than DINO | Open-source image representation models · ImageNet | déjà vu memorization | Mixed |
Surprising findings
- Pairwise sample-level agreement among the reference models is only about 40%, even though the top-5 most correlated classes are identical across methods.
- The one-model test slightly overestimates memorization relative to the two-model test in the VLM setting.
Limitations
- Alternative dataset-level correlation estimators may be poor approximations to the Bayes-optimal predictor or may themselves memorize training data.
- Additional object annotations (Grounded-SAM, Detic) may be lower quality and bias results.
- Reference models disagree substantially at the sample level (about 40% agreement), so one-model tests can overestimate memorization.
Experimental setup
Datasets: ImageNet Shutterstock (239M image-caption pairs, private) YFCC15M
Benchmarks: ImageNet Shutterstock public set
Metrics: déjà vu score déjà vu score at p% population precision gap (PPG) population recall gap (PRG) AUC gap
Baselines: two-model déjà vu test KNN classifier VICReg Barlow Twins DINO
Builds on: déjà vu memorization CLIP OpenCLIP
Closest papers by meaning
- Déjà Vu Memorization in Vision–Language Models (NeurIPS 2024 · similarity 0.92)
- Towards Memorization Estimation: Fast, Formal and Free (ICML 2025 · similarity 0.86)
- Memorization Through the Lens of Curvature of Loss Function Around Samples (ICML 2024 · similarity 0.85)
- On the Memorization of Consistency Distillation for Diffusion Models (NeurIPS 2026 · similarity 0.84)
- Measuring Representational Shifts in Continual Learning: A Linear Transformation Perspective (ICML 2025 · similarity 0.84)
- A Geometric Framework for Understanding Memorization in Generative Models (ICLR 2025 · similarity 0.84)
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