Exploring Motion-Language Alignment for Text-driven Motion Generation
Authors: Ruxi Gu, Zilei Wang, Wei Wang
Organizations: Department of Automation, University of Science and Technology of China, Hefei, China · State Key Laboratory of General Artificial Intelligence, BIGAI, Beijing, China
Text-driven human motion generation aims to synthesize realistic motion sequences that follow textual descriptions. Despite recent advances, accurately aligning motion dynamics with textual semantics remains a fundamental challenge. In this paper, we revisit text-to-motion generation from the perspective of motion-language alignment and propose MLA-Gen, a framework that integrates global motion priors with fine-grained local conditioning. This design enables the model to capture common motion patterns, while establishing detailed alignment between texts and motions. Furthermore, we identify a previously overlooked attention sink phenomenon in human motion generation, where attention disproportionately concentrates on the start text token, limiting the utilization of informative textual cues and leading to degraded semantic grounding. To analyze this issue, we introduce SinkRatio, a metric for measuring attention concentration, and develop alignment-aware masking and control strategies to regulate attention during generation. Extensive experiments demonstrate that our approach consistently improves both motion quality and motion-language alignment over strong baselines.
Figures & tables
Figure 1: Failure cases from previous text-to-motion generation framework [ 26 ] . The color gradient from dark to light represents the temporal flow.
Figure 2: Overview of our MLA-Gen framework. It comprises three complementary components: Memory Slots for capturing global motion priors, Motion-Language Alignment for providing fine-grained textual semantics, and a SinkRatio-based mechanism that models and mitigates the attention sink during both attention computation ( sink-mask ) and sampling ( sink-ctrl ).
Figure 3: Heatmap of the memory slots activation. Regions rendered in brighter yellow indicate higher attention weights between the corresponding motion frames and memory slots.
Figure 4: Heatmap of motion-language alignment. Regions in brighter yellow indicate higher attention weights between the corresponding motion frames and text tokens.
Figure 5: Heatmaps comparison of alignment on the masked model (left) and the unmasked model (right).
Figure 6: SinkRatio curves for masked and unmasked models. Each curve depicts the mean SinkRatio across all batch samples over timesteps, with the shaded region indicating the standard deviation.
Methods
FID ↓
R-Precision ↑
Matching ↓
MModality ↑
CLIP-score ↑
Top 1
Top 2
Top 3
Real
0.000 ±.000
0.503 ±.002
0.696 ±.001
0.795 ±.002
3.244 ±.005
-
0.639 ±.001
MotionDiffuse
0.778 ±.005
0.450 ±.006
0.641 ±.005
0.753 ±.005
3.490 ±.023
3.179 ±.046
0.606 ±.004
ReMoDiffuse
0.883 ±.021
0.468 ±.003
0.653 ±.003
0.754 ±.005
3.414 ±.020
2.703 ±.154
0.621 ±.003
MLD++
2.027 ±.021
0.500 ±.003
0.691 ±.002
0.789 ±.001
3.220 ±.008
1.924 ±.065
0.639 ±.002
MotionLCM V2
2.267 ±.023
0.501 ±.002
0.693 ±.002
0.790 ±.002
3.192 ±.009
1.780 ±.062
0.640 ±.003
Table 1: Quantitative text-to-motion evaluation on HumanML3D dataset. We repeat the evaluation 20 times and report the average with 95% confidence interval. We use bold face/underline to indicate the best/2nd results, and asterisk (*) to indicate the better results between our method and ACMDM [ 26 ] .
Method
FID ↓
R-Top1 ↑
R-Top2 ↑
R-Top3 ↑
MotionDiffuse
3.845
0.344
0.536
0.658
ReMoDiffuse
1.725
0.356
0.572
0.706
MARDM- ϵ
0.340
0.375
0.597
0.739
MARDM-v
0.242
0.387
0.610
0.749
ACMDM
0.237
0.391
0.615
0.752
MLA-Gen-S
0.199
0.392
0.615
0.744
Table 2: Evaluation results on KIT-ML dataset.
Figure 7: Visualization comparison between ACMDM-S [ 26 ] and our MLA-Gen-S.
Methods
FID ↓
R-Top1 ↑
R-Top2 ↑
R-Top3 ↑
+ M + A + S
0.056
0.507
0.698
0.795
+ M + A
0.076
0.508
0.703
0.799
+ M
0.110
0.506
0.699
0.797
+ A
0.101
0.508
0.702
0.799
w/o any modules
0.120
0.507
0.702
0.798
Table 3: Ablation study of MLA-Gen. We use bold face to denote the original configurations.
Appendix figures & tables11 assets
Supplementary material from the paper’s appendix.
Appendix
Name
Meaning
Value
ep
Number of training epochs
500
opt
Training optimizer
AdamW
lr
Learning rate
2e-4
lr-decay
Weight decay
0.1
S
Number of slots
16
λ
Local cond scale
0.2
Appendix
Table 4: Hyperparameter settings. Hyperparameters listed above the dividing line are those required for training, while those below correspond specifically to the MLA-Gen model.
Methods
FID ↓
R-Precision ↑
Top 1
Top 2
Top 3
λ=0.1
0.089
0.508
0.703
0.799
λ=0.2
0.076
0.508
0.703
0.798
λ=0.4
0.089
0.501
0.695
0.793
λ=0.6
0.095
0.499
0.692
0.788
learnable λ
0.118
0.510
0.703
0.799
Appendix
Table 5: Ablation study of the local-to-global fusion factor λ . We use gray shade and bold face to indicate the original configurations in our MLA-Gen.
S
FID ↓
R-Top1 ↑
R-Top2 ↑
R-Top3 ↑
4
0.081
0.501
0.696
0.793
8
0.081
0.503
0.696
0.791
12
0.056
0.507
0.697
0.796
16
0.056
0.507
0.698
0.795
Appendix
Table 6: Ablation study on MLA-Gen-S of slot number S .
Methods
FID ↓
R-Precision ↑
Top 1
Top 2
Top 3
top-1
0.051
0.506
0.698
0.793
top-2
0.056
0.507
0.698
0.795
top-3
0.059
0.507
0.699
0.794
Appendix
Table 7: Ablation study of the top- K algorithm in SinkRatio.
Methods
FID ↓
Top-1 ↑
Top-2 ↑
Top-3 ↑
strong mask
0.056
0.507
0.698
0.795
weak mask
0.069
0.505
0.697
0.795
no mask
0.099
0.508
0.700
0.797
Appendix
Table 8: Ablation of the sink-mask mechanism. Strong and weak masks correspond to tthresh=0.2 and 0.6 .
Methods
FID ↓
Top-1 ↑
Top-2 ↑
Top-3 ↑
Cl
0.056
0.507
0.698
0.795
0.5Cl
0.070
0.506
0.699
0.795
0
0.101
0.505
0.698
0.793
Appendix
Table 9: Ablation of local conditioning in the CFG unconditional branch. Cl , 0.5Cl , and 0 indicate full, limited, and no conditional information in Xuncond generation, respectively.
A person walks and steps onto an elevated surface before stepping down.
Appendix
Table 10: Mapping between video pair paths and their corresponding textual descriptions. Each pair contains results from ACMDM and our method (MLA-Gen), respectively.
Methods
FID ↓
Top-1 ↑
Top-2 ↑
Top-3 ↑
sink-ctrl ( w=3.5 )
0.044
0.501
0.693
0.790
sink-ctrl ( w=4 )
0.056
0.507
0.698
0.795
sink-ctrl ( w=4.5 )
0.084
0.509
0.700
0.796
cfg-ctrl ( w=3.5 )
0.048
0.502
0.694
0.791
cfg-ctrl ( w=4 )
0.068
0.506
0.699
0.794
cfg-ctrl ( w=4.5 )
0.110
0.507
0.701
0.796
Appendix
Table 11: Ablation of CFG strategies under different guidance scales.
Figure 8: A failure case of MLA-Gen with a very long textual description.
Figure 9: Heatmap sequences of the masked model across increasing timesteps. Heatmaps are arranged in a left-to-right, top-to-bottom order. Brighter yellow regions indicate higher attention weights between motion frames and text tokens.
Figure 10: Heatmap sequences of the unmasked model across increasing timesteps.
School of Artificial Intelligence and Data Science, University of Science and Technology of China · Suzhou Institute for Advanced Research, University of Science and Technology of China