REVIEW 4 major objections 6 minor 40 references
Improving Multimodal Learning Balance and Sufficiency through Data Remixing
T0 review · 4 major / 6 minor · reviewed 2026-08-07 · deepseek-v4-flash
Pith's one-line read Batch-level interference, not just slow modalities, causes weak multimodal learning; Data Remixing trains each batch on one modality and lifts accuracy by up to 6.5 percentage points.
desk verdict A plausible training recipe with consistent empirical gains, but the paper's interference-removal story doesn't hold up under scrutiny. read the letter →
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
The reading
What carries the argument
The machinery is a two-stage data-remixing schedule. Stage one is a sample-level unimodal capability score: for each sample, compute the KL divergence $D_{\mathrm{KL}}(p^k_i \| U)$ between each modality's prediction and the uniform distribution; the modality with the smaller value is judged less separable, i.e. weaker on that sample, and is the only modality kept. Stage two is a batch-composition constraint: after partitioning the data into subsets $\mathcal{D}_{m_k}$ by retained modality, every mini-batch is drawn entirely from one subset, so the batch gradient mixes gradients of only one modality. The paper argues that this algebraically removes the cross-modal interference terms from the batch cross-entropy loss, making each modality's update direction consistent with a unimodal objective.
What would settle it
Measure, on a held-out dataset, the angle between a batch's gradient and the gradient of the same samples with only one modality active; the paper predicts this discrepancy is smaller after reassembling. If mixed-modality batches show no larger discrepancy than remixed batches, or if single-modality batches reduce accuracy on a task where cross-modal complementarity is essential, the batch-level story is incomplete.
Extended reading notes
Core claim
The paper's central claim is that insufficient and imbalanced multimodal learning has a batch-level cause: even after decoupling multimodal data into unimodal samples, a batch containing both modalities still produces gradient updates whose directions interfere, so each modality deviates from its ideal optimization path. Data Remixing therefore consists of two linked operations: decoupling, in which each sample is assigned to the modality whose unimodal prediction has the smaller KL divergence to the uniform distribution (the weaker modality), with other modalities masked to zero; and reassembling, in which the decoupled subsets are sampled so that each mini-batch $B_i$ satisfies $B_i \subseteq \mathcal{D}_{m_k}$ for one modality $k$. The paper shows that with such batches, the cross-entropy loss no longer mixes $W^{a}z^{a}$ and $W^{v}z^{v}$ terms for different modalities within a batch, which it identifies as the source of modality clash. After a warm-up stage on the full multimodal data, training alternates between modality-specific batches, exposing the weak modality to more samples and aligning each modality's gradient direction, yielding the reported gains.
Load-bearing premise
The central assumption is that interference between modalities arises from putting different modalities in the same training batch, and that removing that mixing by training each batch on a single modality improves multimodal learning without sacrificing the cross-modal features that joint training is meant to provide.
Editorial extensions
If this is right
- Data Remixing can be layered on top of existing balance methods: combining it with MLA gives 74.19% on CREMAD and with Resample gives 58.40% on Kinetic-Sounds, beating either method alone.
- The strategy generalizes across fusion choices—concatenation, summation, decision fusion—and across intermediate-fusion architectures such as MMTM and CentralNet, so it is not tied to one model design.
- Because the training set is not expanded, Data Remixing converges faster in wall-clock time than Resample and MLA under the same hardware and batch size.
- Reassembling single-modality batches aligns each modality's gradient direction with its ideal direction, which the paper demonstrates by measuring gradient-angle discrepancies during training on CREMAD.
Reading between the lines
- Extension: if batch-level interference is the true bottleneck, the same remixing schedule should transfer to other paired-modality objectives such as audiovisual retrieval or video captioning, where batch composition is equally controllable.
- Extension: the KL-to-uniform score is a cheap proxy for sample-level weakness; a testable variant would use per-sample holdout validation or true-label confidence to assign samples, and check whether the accuracy gains change.
- Extension: the mechanism predicts a measurable signature—the cosine angle between a batch update and a pure unimodal update should be consistently smaller for remixed batches; tracking this for both modalities, not just the strong one, would sharpen the evidence.
- Extension: the paper's stated auxiliary-modality limitation suggests a boundary: when one channel carries almost no task information, over-allocating training to it could waste capacity, and the allocation rule may need a floor on how many samples each modality receives.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper proposes a training strategy called Data Remixing for multimodal models, targeting the two problems of modality laziness (weak modalities learning too slowly) and modality clash (cross-modal gradient interference). The method first decouples multimodal inputs by evaluating per-sample unimodal separability using KL divergence to a uniform distribution, retaining only the weaker modality for each sample. It then reassembles training batches so that each batch contains samples from only one such modality subset, with the non-selected modalities masked to zero. The authors claim this batch-level control eliminates cross-modal interference, and demonstrate on CREMAD and Kinetic-Sounds consistent accuracy improvements over conventional fusion baselines and several prior imbalance-aware methods, without dataset expansion or inference overhead. The paper includes ablations of the two components, analyses of sample allocation and gradient alignment, and comparisons of unimodal prediction strategies.
Significance. If the empirical results hold, the method is attractive for its simplicity, architecture-agnosticism, and consistent gains across two audio-visual benchmarks and multiple fusion architectures (Concat, Summation, Decision Fusion, FiLM, Bi-Gated, MMTM, CentralNet). The authors provide the source code, and the ablations give some support for both design choices. However, the paper's central mechanistic claim—that mixing modalities within a batch causes interference and that single-modality batches with zeroed other modalities remove that interference—is undermined by an incorrect simplification in the derivation of Eq. (10). The claimed batch-level novelty therefore needs either a corrected mechanism with supporting evidence or a revised, more modest framing. The empirical gains are still potentially valuable, but the current explanation does not reliably attribute them to the stated cause.
major comments (4)
- [Section 3.2, Eq. (10)] The simplification of the batch loss to depend only on the retained modality assumes that masking a modality input to zero yields a zero encoder output (z_a = 0). Under the architecture used in Section 4.1 (ResNet-18 encoders), this is false: BatchNorm layers apply an affine transformation to a zero input using running statistics, and residual connections propagate nonzero signals, so a zeroed input still produces a nonzero feature vector. Consequently, the zeroed modality still contributes to f(x_i) in Eq. (5) and still receives nonzero gradients from the batch loss. The claimed elimination of cross-modal interference at the batch level is therefore not actually achieved by the described procedure. Please provide empirical evidence that the contribution of the zeroed branch is negligible for the trained encoders (e.g., gradient norms of the masked branch), or modify the method to explicitly zero the encoder output (or detach the gradient) for the non-selected modality and re-run the experiments. This is load-bearing because the paper's central novelty is the batch-level interference-removal mechanism.
- [Section 4.5.1, Table 5] The 'Reassemble' ablation is described as reassembling batches without modality masking ('without modality masking'). However, the formal definition of the modality subset in Eq. (7) requires that non-selected modalities are zeroed: D_mk = {x_i | x_j_i = 0 for all j ≠ k}. Without masking, each sample still contains both modalities, so the batch does not satisfy the condition in Eq. (9) as formalized. The ablation therefore cannot isolate the effect of batch-level reassembling under the proposed mechanism; the improvement could be due to a change in sampling distribution (e.g., over-sampling the weak modality) rather than to the removal of cross-modal interference via zeroed inputs. Please include an ablation that reassembles batches while masking the non-selected modality (the full Eqs. 7-9 setup) and report the individual contributions of masking and batch composition separately.
- [Section 4.3, Table 3] The text states 'our approach neither expands the dataset nor reduces the model's training efficiency,' but Table 3 shows that Remix training time to convergence is 2537s on CREMAD and 4946s on Kinetic-Sounds, compared to 1536s and 3849s for the baseline—an increase of about 65% and 29%, respectively. This directly contradicts the stated claim about training efficiency. Please revise the claim to state that the method does not expand the dataset, that it is more efficient than Resample and MLA, and acknowledge a non-negligible increase in training time relative to the plain baseline.
- [Abstract and Section 1] The headline numbers 'approximately 6.50% up on CREMAD and 3.41% up on Kinetic-Sounds' do not match any comparison reported in Table 2. The improvement of Remix over the Concatenation baseline is 8.20% and 5.40%; the improvement of MLA+Remix over MLA is 6.18% and 3.09%; Resample+Remix over Resample is 5.64% and 3.23%. Please clarify the reference baseline for the claimed 6.50% and 3.41% figures, or correct the numbers and the associated text.
minor comments (6)
- [Section 3.1, Eq. (1)] The weights w_k in the auxiliary losses are not specified; please state how they are chosen in the experiments (e.g., all equal to 1) and whether they are tuned per dataset.
- [Section 4.1] The paper reports averages over three random seeds but no standard deviations or confidence intervals; please include variance information in the tables or at least in an appendix.
- [Section 4.2] The 'Decision fusion' method (Gunes & Piccardi, 2005) is not defined; please specify the exact aggregation rule (e.g., averaging softmax probabilities) to ensure reproducibility.
- [Section 4.5.3] The reported unimodal accuracy improvements (audio +1.75%, video +2.96% on CREMAD) are not tied to a clearly defined baseline; please specify whether these are relative to the baseline model's unimodal classification heads and at which training stage they are measured.
- [Figure 3(c)] The 'ideal guidance direction' used to compute gradient alignment is not defined; please specify how it is computed and which gradient (e.g., of the audio branch) is being measured.
- [Algorithm 1] The warm-up epoch count E_r is a free parameter; the text mentions a 10-epoch warm-up, but please state explicitly whether the same value is used for both datasets and whether it was tuned.
Circularity Check
No circularity: Data Remixing gains are measured against external baselines, and Eq. 10 is a motivational tautology rather than a fitted prediction.
full rationale
The paper's central claim is an empirical accuracy improvement, and every reported result is obtained by training on fixed external benchmarks (CREMA-D, Kinetic-Sounds) and comparing against standard baselines. No parameter is fitted to the target results, and no reported number is derived by plugging the paper's own output back into a formula. The closest thing to a self-referential step is Eq. (10), where masking one modality to zero and restricting each batch to one modality subset removes that modality's term from the loss expression. That simplification is definitional and tautological, but the paper uses it only as motivation for the batch-level reassembling hypothesis; the ablations in Table 5 and the gradient-direction measurements in Fig. 3(c) are independent empirical checks. The authors cite prior work for baselines and standard techniques, but these are not self-citations carrying a load-bearing uniqueness theorem or a forbidden-alternative argument. Concerns about BatchNorm making zeroed inputs produce nonzero features bear on the technical validity of Eq. (10)'s simplification, but that is an empirical correctness issue, not a circular reduction. The derivation chain therefore does not reduce to its own inputs, and the central claim is externally testable.
Assumptions & free parameters
free parameters (2)
- Warm-up epochs Er =
10
- Unimodal loss weights w_k in Eq. (1)
assumptions (3)
- domain assumption KL divergence of unimodal prediction probabilities to a uniform distribution is a valid measure of per-sample modality capability.
- domain assumption Cross-modal gradient interference at the batch level is harmful, and eliminating it by training on single-modality batches improves learning.
- domain assumption The multimodal model's fused output benefits from separately trained unimodal branches that are later combined during inference.
Cite this review
Pith. "Pith review of Improving Multimodal Learning Balance and Sufficiency through Data Remixing." pith.science (2026). https://pith.science/paper/YKYRP2DZ
@misc{pith2026250611550,
author = {Pith},
title = {Pith review of: Improving Multimodal Learning Balance and Sufficiency through Data Remixing},
year = {2026},
howpublished = {\url{https://pith.science/paper/YKYRP2DZ}},
note = {Machine review of arXiv:2506.11550}
}
abstract
Different modalities hold considerable gaps in optimization trajectories, including speeds and paths, which lead to modality laziness and modality clash when jointly training multimodal models, resulting in insufficient and imbalanced multimodal learning. Existing methods focus on enforcing the weak modality by adding modality-specific optimization objectives, aligning their optimization speeds, or decomposing multimodal learning to enhance unimodal learning. These methods fail to achieve both unimodal sufficiency and multimodal balance. In this paper, we, for the first time, address both concerns by proposing multimodal Data Remixing, including decoupling multimodal data and filtering hard samples for each modality to mitigate modality imbalance; and then batch-level reassembling to align the gradient directions and avoid cross-modal interference, thus enhancing unimodal learning sufficiency. Experimental results demonstrate that our method can be seamlessly integrated with existing approaches, improving accuracy by approximately 6.50%$\uparrow$ on CREMAD and 3.41%$\uparrow$ on Kinetic-Sounds, without training set expansion or additional computational overhead during inference. The source code is available at https://github.com/MatthewMaxy/Remix_ICML2025.
Figures
Reference graph
Works this paper leans on
-
[1]
write newline
" write newline "" before.all 'output.state := FUNCTION n.dashify 't := "" t empty not t #1 #1 substring "-" = t #1 #2 substring "--" = not "--" * t #2 global.max substring 't := t #1 #1 substring "-" = "-" * t #2 global.max substring 't := while if t #1 #1 substring * t #2 global.max substring 't := if while FUNCTION format.date year duplicate empty "emp...
-
[2]
and Zisserman, A
Arandjelovic, R. and Zisserman, A. Look, listen and learn. In Proceedings of the IEEE international conference on computer vision, pp.\ 609--617, 2017
2017
-
[3]
G., Keutmann, M
Cao, H., Cooper, D. G., Keutmann, M. K., Gur, R. C., Nenkova, A., and Verma, R. Crema-d: Crowd-sourced emotional multimodal actors dataset. IEEE transactions on affective computing, 5 0 (4): 0 377--390, 2014
2014
-
[4]
Improving multi-modal learning with uni-modal teachers
Du, C., Li, T., Liu, Y., Wen, Z., Hua, T., Wang, Y., and Zhao, H. Improving multi-modal learning with uni-modal teachers. arXiv preprint arXiv:2106.11059, 2021
arXiv 2021
-
[5]
On uni-modal feature learning in supervised multi-modal learning
Du, C., Teng, J., Li, T., Liu, Y., Yuan, T., Wang, Y., Yuan, Y., and Zhao, H. On uni-modal feature learning in supervised multi-modal learning. In International Conference on Machine Learning, pp.\ 8632--8656. PMLR, 2023
work page 2023
-
[6]
Pmr: Prototypical modal rebalance for multimodal learning
Fan, Y., Xu, W., Wang, H., Wang, J., and Guo, S. Pmr: Prototypical modal rebalance for multimodal learning. In Proceedings of the IEEE/CVF Conference on Computer Vision and Pattern Recognition, pp.\ 20029--20038, 2023
2023
-
[7]
Multimodal imbalance-aware gradient modulation for weakly-supervised audio-visual video parsing
Fu, J., Gao, J., Bao, B.-K., and Xu, C. Multimodal imbalance-aware gradient modulation for weakly-supervised audio-visual video parsing. IEEE Transactions on Circuits and Systems for Video Technology, 2023
work page 2023
-
[8]
Ghorbani, A. and Zou, J. Y. Neuron shapley: Discovering the responsible neurons. Advances in neural information processing systems, 33: 0 5922--5932, 2020
work page 2020
Show all 40 references
-
[9]
and Piccardi, M
Gunes, H. and Piccardi, M. Affect recognition from face and body: early fusion vs. late fusion. In 2005 IEEE international conference on systems, man and cybernetics, volume 4, pp.\ 3437--3443. IEEE, 2005
2005
-
[10]
Deep residual learning for image recognition
He, K., Zhang, X., Ren, S., and Sun, J. Deep residual learning for image recognition. In Proceedings of the IEEE conference on computer vision and pattern recognition, pp.\ 770--778, 2016
2016
-
[11]
Multimodal temporal attention in sentiment analysis
He, Y., Sun, L., Lian, Z., Liu, B., Tao, J., Wang, M., and Cheng, Y. Multimodal temporal attention in sentiment analysis. In Proceedings of the 3rd International on Multimodal Sentiment Analysis Workshop and Challenge, pp.\ 61--66, 2022
2022
-
[12]
Improving neural networks by preventing co-adaptation of feature detectors
Hinton, G. Improving neural networks by preventing co-adaptation of feature detectors. arXiv preprint arXiv:1207.0580, 2012
2012 arXiv
-
[13]
Modality competition: What makes joint training of multi-modal network fail in deep learning?(provably)
Huang, Y., Lin, J., Zhou, C., Yang, H., and Huang, L. Modality competition: What makes joint training of multi-modal network fail in deep learning?(provably). In International conference on machine learning, pp.\ 9226--9259. PMLR, 2022
2022
-
[14]
Joze, H. R. V., Shaban, A., Iuzzolino, M. L., and Koishida, K. Mmtm: Multimodal transfer module for cnn fusion. In Proceedings of the IEEE/CVF conference on computer vision and pattern recognition, pp.\ 13289--13299, 2020
2020
-
[15]
The kinetics human action video dataset
Kay, W., Carreira, J., Simonyan, K., Zhang, B., Hillier, C., Vijayanarasimhan, S., Viola, F., Green, T., Back, T., Natsev, P., et al. The kinetics human action video dataset. arXiv preprint arXiv:1705.06950, 2017
2017 arXiv
-
[16]
Efficient large-scale multi-modal classification
Kiela, D., Grave, E., Joulin, A., and Mikolov, T. Efficient large-scale multi-modal classification. In Proceedings of the AAAI conference on artificial intelligence, volume 32, 2018
2018
-
[17]
Kingma, D. P. Adam: A method for stochastic optimization. arXiv preprint arXiv:1412.6980, 2014
2014 arXiv
-
[18]
Improving multimodal learning with multi-loss gradient modulation
Kontras, K., Chatzichristos, C., Blaschko, M., and De Vos, M. Improving multimodal learning with multi-loss gradient modulation. arXiv preprint arXiv:2405.07930, 2024
2024 arXiv
-
[19]
Boosting multi-modal model performance with adaptive gradient modulation
Li, H., Li, X., Hu, P., Lei, Y., Li, C., and Zhou, Y. Boosting multi-modal model performance with adaptive gradient modulation. In Proceedings of the IEEE/CVF International Conference on Computer Vision, pp.\ 22214--22224, 2023
2023
-
[20]
Variational probabilistic fusion network for rgb-t semantic segmentation
Lin, B., Lin, Z., Guo, Y., Zhang, Y., Zou, J., and Fan, S. Variational probabilistic fusion network for rgb-t semantic segmentation. arXiv preprint arXiv:2307.08536, 2023
2023 arXiv
-
[21]
Umap: Uniform manifold approximation and projection for dimension reduction
McInnes, L., Healy, J., and Melville, J. Umap: Uniform manifold approximation and projection for dimension reduction. arXiv preprint arXiv:1802.03426, 2018
2018 arXiv
-
[22]
Y., et al
Ngiam, J., Khosla, A., Kim, M., Nam, J., Lee, H., Ng, A. Y., et al. Multimodal deep learning. In ICML, volume 11, pp.\ 689--696, 2011
2011
-
[23]
and Efros, A
Owens, A. and Efros, A. A. Audio-visual scene analysis with self-supervised multisensory features. In Proceedings of the European conference on computer vision (ECCV), pp.\ 631--648, 2018
2018
-
[24]
Balanced multimodal learning via on-the-fly gradient modulation
Peng, X., Wei, Y., Deng, A., Wang, D., and Hu, D. Balanced multimodal learning via on-the-fly gradient modulation. In Proceedings of the IEEE/CVF conference on computer vision and pattern recognition, pp.\ 8238--8247, 2022
2022
-
[25]
Film: Visual reasoning with a general conditioning layer
Perez, E., Strub, F., De Vries, H., Dumoulin, V., and Courville, A. Film: Visual reasoning with a general conditioning layer. In Proceedings of the AAAI conference on artificial intelligence, volume 32, 2018
2018
-
[26]
Graph interactive network with adaptive gradient for multi-modal rumor detection
Sun, T., Qian, Z., Li, P., and Zhu, Q. Graph interactive network with adaptive gradient for multi-modal rumor detection. In Proceedings of the 2023 ACM International Conference on Multimedia Retrieval, pp.\ 316--324, 2023
2023
-
[27]
Learning to balance the learning rates between various modalities via adaptive tracking factor
Sun, Y., Mai, S., and Hu, H. Learning to balance the learning rates between various modalities via adaptive tracking factor. IEEE Signal Processing Letters, 28: 0 1650--1654, 2021
2021
-
[28]
and Hinton, G
Van der Maaten, L. and Hinton, G. Visualizing data using t-sne. Journal of machine learning research, 9 0 (11), 2008
2008
-
[29]
Centralnet: a multilayer approach for multimodal fusion
Vielzeuf, V., Lechervy, A., Pateux, S., and Jurie, F. Centralnet: a multilayer approach for multimodal fusion. In Proceedings of the European Conference on Computer Vision (ECCV) Workshops, pp.\ 0--0, 2018
2018
-
[30]
What makes training multi-modal classification networks hard? In Proceedings of the IEEE/CVF conference on computer vision and pattern recognition, pp.\ 12695--12705, 2020
Wang, W., Tran, D., and Feiszli, M. What makes training multi-modal classification networks hard? In Proceedings of the IEEE/CVF conference on computer vision and pattern recognition, pp.\ 12695--12705, 2020
2020
-
[31]
and Hu, D
Wei, Y. and Hu, D. Mmpareto: Boosting multimodal learning with innocent unimodal assistance. In International Conference on Machine Learning, pp.\ 52559--52572. PMLR, 2024
2024
-
[32]
Enhancing multimodal cooperation via sample-level modality valuation
Wei, Y., Feng, R., Wang, Z., and Hu, D. Enhancing multimodal cooperation via sample-level modality valuation. In Proceedings of the IEEE/CVF Conference on Computer Vision and Pattern Recognition, pp.\ 27338--27347, 2024
2024
-
[33]
Diagnosing and re-learning for balanced multimodal learning
Wei, Y., Li, S., Feng, R., and Hu, D. Diagnosing and re-learning for balanced multimodal learning. In European Conference on Computer Vision, pp.\ 71--86. Springer, 2025
2025
-
[34]
Wu, N., Jastrzebski, S., Cho, K., and Geras, K. J. Characterizing and overcoming the greedy nature of learning in multi-modal deep neural networks. In International Conference on Machine Learning, pp.\ 24043--24055. PMLR, 2022
2022
-
[35]
Mmcosine: Multi-modal cosine loss towards balanced audio-visual fine-grained learning
Xu, R., Feng, R., Zhang, S.-X., and Hu, D. Mmcosine: Multi-modal cosine loss towards balanced audio-visual fine-grained learning. In ICASSP 2023-2023 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), pp.\ 1--5. IEEE, 2023
2023
-
[36]
Mcl: A contrastive learning method for multimodal data fusion in violence detection
Yang, L., Wu, Z., Hong, J., and Long, J. Mcl: A contrastive learning method for multimodal data fusion in violence detection. IEEE Signal Processing Letters, 30: 0 408--412, 2022
2022
-
[37]
Multimodal fusion on low-quality data: A comprehensive survey
Zhang, Q., Wei, Y., Han, Z., Fu, H., Peng, X., Deng, C., Hu, Q., Xu, C., Wen, J., Hu, D., et al. Multimodal fusion on low-quality data: A comprehensive survey. arXiv preprint arXiv:2404.18947, 2024 a
2024 arXiv
-
[38]
Multimodal representation learning by alternating unimodal adaptation
Zhang, X., Yoon, J., Bansal, M., and Yao, H. Multimodal representation learning by alternating unimodal adaptation. In Proceedings of the IEEE/CVF Conference on Computer Vision and Pattern Recognition, pp.\ 27456--27466, 2024 b
2024
-
[39]
Adaptive mask co-optimization for modal dependence in multimodal learning
Zhou, Y., Liang, X., Zheng, S., Xuan, H., and Kumada, T. Adaptive mask co-optimization for modal dependence in multimodal learning. In ICASSP 2023-2023 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), pp.\ 1--5. IEEE, 2023
2023
-
[40]
Vision+ x: A survey on multimodal learning in the light of data
Zhu, Y., Wu, Y., Sebe, N., and Yan, Y. Vision+ x: A survey on multimodal learning in the light of data. IEEE Transactions on Pattern Analysis and Machine Intelligence, 2024
2024
Reviewed August 7, 2026 · model on record in the stance chip above.
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