Cited by 24Context-Aware Activity Recognition SystemsHuman Mobility and Location-Based AnalysisPhysical Activity and Health

Spatial-Temporal Masked Autoencoder for Multi-Device Wearable Human Activity Recognition

Open access
Miao, Shenghuan, Chen, Ling, Hu, Rong·2023·Proceedings of the ACM on Interactive, Mobile, Wearable and Ubiquitous Technologies

Abstract

The widespread adoption of wearable devices has led to a surge in the development of multi-device wearable human activity recognition (WHAR) systems. Nevertheless, the performance of traditional supervised learning-based methods to WHAR is limited by the challenge of collecting ample annotated wearable data. To overcome this limitation, self-supervised learning (SSL) has emerged as a promising solution by first training a competent feature extractor on a substantial quantity of unlabeled data, followed by refining a minimal classifier with a small amount of labeled data. Despite the promise of SSL in WHAR, the majority of studies have not considered missing device scenarios in multi-device WHAR. To bridge this gap, we propose a multi-device SSL WHAR method termed Spatial-Temporal Masked Autoencoder (STMAE). STMAE captures discriminative activity representations by utilizing the asymmetrical encoder-decoder structure and two-stage spatial-temporal masking strategy, which can exploit the spatial-temporal correlations in multi-device data to improve the performance of SSL WHAR, especially on missing device scenarios. Experiments on four real-world datasets demonstrate the efficacy of STMAE in various practical scenarios.

Integrity signals

Registry

Crossref · 10.1145/3631415

Cites

88 of 88 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

4 of 18 cited sources checked · 1 supported · 1 flagged · accuracy not yet measured

  • Premisecitation

    Self-supervised learning provides a viable solution by pre-training a feature extractor on large unlabeled data and then optimizing a small classifier with limited labeled data.

    “Self-supervised learning (SSL) provides a viable solution by first pre-training a feature extractor on a large amount of unlabeled data and then optimizing a small classifier with limited labeled data [13].”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [13] 13. Shohreh Deldari, Hao Xue, Aaqib Saeed, Jiayuan He, Daniel V Smith, and Flora D Salim. 2022. Beyond just vision: A review on self-supervised representation learning on multimodal and temporal data. arXiv preprint arXiv:2206.02353 (2022). source

      Section 3.1 (pp. 8–9) describes learning an encoder from unlabeled data and transferring it to downstream tasks with limited labeled data, including classification. It does not specify optimizing a small classifier as the second step; the encoder may instead be reused directly or fine-tuned. (LLM, conf=0.84)

      Experimental — accuracy not yet measured
  • Findingown data

    Experiments on four real-world datasets demonstrate STMAE's efficacy in various practical scenarios.

    “Experiments on four real-world datasets demonstrate the efficacy of STMAE in various practical scenarios.”
    Quote in the paperSubstantial claim
  • Findingown data

    STMAE outperforms state-of-the-art baselines on four public datasets.

    “Our evaluation on four public datasets demonstrates that STMAE outperforms the state-of-the-art (SOTA) baselines.”
    Quote in the paperSubstantial claim
  • Findingown data

    The advantage of STMAE is particularly pronounced when only a small number of devices are available.

    “The advantage of STMAE is particularly pronounced when only a small number of devices are available.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Missing device scenarios are an inevitable problem for multi-device WHAR.
  • Findingreasoning

    Opportunity dataset does not reach stable performance even at the maximum labeling rate of 100%.

    “However, Opportunity dataset does not seem to reach stable performance even at the maximum labeling rate of 100%.”
    Quote in the paperSubstantial claim
  • Classified as probably not a substantial claim. 19
  • May combine two claims. 30
  • Classified as probably not a substantial claim.

    Study design and conductcitation

    Leave-one-group-out cross-validation is used for performance evaluation.

    “Leave-one-group-out cross-validation approach is used for performance evaluation follows the previous works [26,34] .”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites [26] 26. Harish Haresamudram, Irfan Essa, and Thomas Plötz. 2021. Contrastive predictive coding for human activity recognition. Proceedings of the ACM on Interactive, Mobile, Wearable and Ubiquitous Technologies 5, 2 (2021), 1-26. source

      Section 4.1 (pp. 7–8) describes participant-based training, validation, and test splits, not leave-one-group-out cross-validation. It says 20% of participants are randomly selected for testing and specifies a fixed participant split for USC-HAD. (LLM, conf=0.88)

      Checked by a reasoning model — may be wrong.

      Experimental — accuracy not yet measured
    • cites [34] 34. Yash Jain, Chi Ian Tang, Chulhong Min, Fahim Kawsar, and Akhil Mathur. 2022. ColloSSL: Collaborative self-supervised learning for human activity recognition. Proceedings of the ACM on Interactive, Mobile, Wearable and Ubiquitous Technologies 6, 1 (2022), 1-28. source
  • May combine two claims.

    Premisecitation

    Activity labeling in wearable data is difficult, reducing the number of available labels.

    “This renders activity labeling difficult, reducing the number of available labels [8,23,30].”
    Quote in the paperSubstantial claim1 of 3 sources checked
    • cites [8] 8. Kaixuan Chen, Dalin Zhang, Lina Yao, Bin Guo, Zhiwen Yu, and Yunhao Liu. 2021. Deep learning for sensor-based human activity recognition: Overview, challenges, and opportunities. Computing Surveys 54, 4 (2021), 1-40. source
    • cites [23] 23. Fuqiang Gu, Mu-Huan Chung, Mark Chignell, Shahrokh Valaee, Baoding Zhou, and Xue Liu. 2021. A survey on deep learning for human activity recognition. Computing Surveys 54, 8 (2021), 1-34.

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [30] 30. Rong Hu, Ling Chen, Shenghuan Miao, and Xing Tang. 2023. SWL-Adapt: An unsupervised domain adaptation model with sample weight learning for cross-user wearable human activity recognition. In Proceedings of the AAAI Conference on Artificial Intelligence, Vol. 37. 6012-6020. source
  • May combine two claims.

    Findingown data

    On RealWorld and PAMAP datasets, CPC and Masked Reconstruction achieve the best performance, respectively.

    “On RealWorld and PAMAP datasets, CPC [26] and Masked Reconstruction [25] achieve the best performance, respectively.”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites [26] 26. Harish Haresamudram, Irfan Essa, and Thomas Plötz. 2021. Contrastive predictive coding for human activity recognition. Proceedings of the ACM on Interactive, Mobile, Wearable and Ubiquitous Technologies 5, 2 (2021), 1-26. source

      The citation to this paper is attached to CPC’s performance on RealWorld, not to masked reconstruction on PAMAP. Section 5.1 (p. 10) reports CPC results for Mobiact, Motionsense, USC-HAD and UCI-HAR, but the passages found when searching for RealWorld do not establish its performance on that dataset. (LLM, conf=0.76)

      Experimental — accuracy not yet measured
    • cites [25] 25. Harish Haresamudram, Apoorva Beedu, Varun Agrawal, Patrick L Grady, Irfan Essa, Judy Hoffman, and Thomas Plötz. 2020. Masked reconstruction based self-supervision for human activity recognition. In Proceedings of the International Symposium on Wearable Computers. 45-49. source
  • May combine two claims.

    Findingown data

    STMAE outperforms the best SSL baselines by 5.41%, 2.81%, 3.95%, and 5.00% on Opportunity, RealWorld, Realdisp, and PAMAP, respectively.

    “STMAE outperforms the best SSL baselines by 5.41%, 2.81%, 3.95%, and 5.00% on Opportunity, RealWorld, Realdisp, and PAMAP, respectively.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    The macro F1-score fluctuates noticeably with changes in the temporal masking probability, and this behavior depends on the dataset.

    “The macro F1-score fluctuates noticeably with changes in the temporal masking probability, and this behavior depends on the dataset.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data

    Increasing the number of CNN layers can enhance the representation capability of the network, but the impact on performance improvement is limited.

    “Our results, as shown in Fig. 5, suggest that while increasing the number of CNN layers can enhance the representation capability of the network, the impact on performance improvement is limited.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingreasoning

    For Opportunity and RealWorld datasets, the macro F1-score initially increases as the temporal masking probability increases, reaching a sweet point, and then decreases as the temporal masking probability continues to increase.

    “For Opportunity and RealWorld datasets, the macro F1-score initially increases as the temporal masking probability increases, reaching a sweet point, and then decreases as the temporal masking probability continues to increase.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingreasoning

    RealWorld dataset exhibits slight improvement in performance with an increasing number of CNN layers, but the improvement is not significant.

    “On the other hand, RealWorld dataset exhibits slight improvement in performance with an increasing number of CNN layers, but the improvement is not significant.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data

    STMAE outperforms other variants and achieves the best performance.

    “Specifically, STMAE outperforms other variants and achieves the best performance.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    The total training time of STMAE on Opportunity dataset using a Raspberry Pi 4 Model B was 16.82 min, with an associated energy consumption of 47.67 KJ.

    “In supervised learning phase, the total training time was 16.82 min, with an associated energy consumption of 47.67 KJfoot_1 .”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    The Transformer structure is superior in both the complete masking setting and the without temporal masking setting.

    “The results demonstrate the superiority of the Transformer structure in both masking settings.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    In inference phase, each sample's inference time was 41.17 ms, with an associated energy consumption of 163.90 mJ.

    “In inference phase, each sample's inference time was 41.17 ms, with an associated energy consumption of 163.90 mJ 1 .”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Interpretationreasoning

    The inter-activity similarity and intra-activity variability imply instances are biased easily in WHAR, exacerbating the difficulty of constructing positive and negative samples in contrastive learning.

    “The inter-activity similarity and intra-activity variability imply instances are biased easily in WHAR, which exacerbate the difficulty of constructing positive and negative samples in contrastive learning.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Premisereasoning

    The available devices in multi-device WHAR are an arbitrary subset of the total devices, which is unpredictable and would severely impact the recognition performance of existing methods.

    “As a result, the available devices are an arbitrary subset of the total devices, which is unpredictable and would severely impact the recognition performance of existing methods.”
    Quote in the paperSubstantial claim0 of 5 sources checked
    • cites [19] 19. Berihun Fekade, Taras Maksymyuk, Maryan Kyryk, and Minho Jo. 2017. Probabilistic recovery of incomplete sensed data in IoT. IEEE Internet of Things Journal 5, 4 (2017), 2282-2292. source
    • cites [33] 33. Farhad Imani, Changqing Cheng, Ruimin Chen, and Hui Yang. 2018. Nested gaussian process modeling for high-dimensional data imputation in healthcare systems. In Proceedings of the IIE Annual Conference. 1312-1317.

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [39] 39. Hua Kang, Qianyi Huang, and Qian Zhang. 2022. Augmented adversarial learning for human activity recognition with partial sensor sets. Proceedings of the ACM on Interactive, Mobile, Wearable and Ubiquitous Technologies 6, 3 (2022), 1-30. source
    • cites [42] 42. Shengzhong Liu, Shuochao Yao, Yifei Huang, Dongxin Liu, Huajie Shao, Yiran Zhao, Jinyang Li, Tianshi Wang, Ruijie Wang, Chaoqi Yang, et al. 2020. Handling missing sensors in topology-aware iot applications with gated graph neural network. Proceedings of the ACM on Interactive, Mobile, Wearable and Ubiquitous Technologies 4, 3 (2020), 1-31. source
    • cites [45] 45. Yang Liu, Zhenjiang Li, Zhidan Liu, and Kaishun Wu. 2019. Real-time arm skeleton tracking and gesture inference tolerant to missing wearable sensors. In Proceedings of the Annual International Conference on Mobile Systems, Applications, and Services. 287-299. source
  • May combine two claims.

    Interpretationreasoning

    STMAE captures discriminative activity representations by using an asymmetrical encoder-decoder structure and a two-stage spatial-temporal masking strategy, exploiting spatial-temporal correlations in multi-device data to improve SSL WHAR performance, especially in missing device scenarios.

    “STMAE captures discriminative activity representations by utilizing the asymmetrical encoder-decoder structure and two-stage spatial-temporal masking strategy, which can exploit the spatial-temporal correlations in multi-device data to improve the performance of SSL WHAR, especially on missing device scenarios.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Premisenone given

    There exists inter-activity similarity and intra-activity variability in WHAR.

    “It is noteworthy that there exists inter-activity similarity and intra-activity variability in WHAR.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S4 (based).

    Interpretationnone given

    The asymmetrical encoder-decoder structure imposes a greater demand on the encoders for learning spatial-temporal correlations that benefits downstream tasks.

    “Such an encoder-decoder structure design can impose a greater demand on the encoders for learning spatial-temporal correlations that benefits downstream tasks.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S4 (based).

    Interpretationreasoning

    The two-stage spatial-temporal masking strategy can handle missing device scenarios effectively.

    “Such a masking strategy design can handle missing device scenarios effectively.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationreasoning

    In Realdisp dataset, fitness activities are highly cyclical and have more homogeneous sub-activities, making them easier for the model to learn.

    “In Realdisp dataset, fitness activities are highly cyclical and have more homogeneous sub-activities, making them easier for the model to learn.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Learning correlations across multiple devices benefits contrastive learning.

    “The authors propose ColloSSL, which demonstrates that learning the correlations across multiple devices benefits contrastive learning.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [34] 34. Yash Jain, Chi Ian Tang, Chulhong Min, Fahim Kawsar, and Akhil Mathur. 2022. ColloSSL: Collaborative self-supervised learning for human activity recognition. Proceedings of the ACM on Interactive, Mobile, Wearable and Ubiquitous Technologies 6, 1 (2022), 1-28. source
  • Probably not a substantial claim: may not pass S4 (based). May combine two claims.

    Interpretationreasoning

    The learned spatial-temporal correlations can help extract versatile activity representations even when only part of devices are available, which is beneficial for downstream tasks.

    “The learned spatial-temporal correlations can help to extract versatile activity representations even when only part of devices are available, which is beneficial for downstream tasks.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationreasoning

    The supervised method is prone to underfitting due to insufficient training data, while STMAE has already learned prior knowledge of wearable data during pre-training, reducing its reliance on labeled data during supervised learning.

    “as the supervised method is prone to underfitting due to insufficient training data, while STMAE has already learned some prior knowledge of wearable data during pre-training, reducing its reliance on labeled data during supervised learning.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Interpretationown data

    One layer of CNN can already meet the needs for spatial fusion, and significant improvement in performance is not necessarily achieved with an increasing number of layers.

    “Overall, our findings suggest that one layer of CNN can already meet the needs for spatial fusion, and that the significant improvement in performance is not necessarily achieved with an increasing number of layers.”
    Quote in the paperSubstantial claim
  • Classified as probably not a substantial claim. May combine two claims.

    Interpretationnone given

    Spatial masking primarily simulates missing device scenarios, while temporal masking prepares for learning temporal correlations by TE.

    “Spatial masking primarily simulates missing device scenarios, while the role of temporal masking is to prepare for learning temporal correlations by TE.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: It is impossible for every user to wear all devices at all time in daily life.
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    In typical deployment of a WHAR model, pre-training is performed in the cloud and supervised learning is performed on local devices.

    “In the typical deployment of a WHAR model [51], the pre-training phase is performed in the cloud to leverage the cloud computing power and large-scale wearable datasets.The supervised learning phase is performed in the local devices (e.g., smartphones) to personalize the WHAR model while ensuring user privacy.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [51] 51. Xiaomin Ouyang, Xian Shuai, Jiayu Zhou, Ivy Wang Shi, Zhiyuan Xie, Guoliang Xing, and Jianwei Huang. 2022. Cosmo: Contrastive fusion learning with small data for multimodal human activity recognition. In Proceedings of the Annual International Conference on Mobile Computing And Networking. 324-337. source
  • May combine two claims.

    Interpretationreasoning

    On PAMAP dataset, w/o TM performs particularly poorly, probably because its corresponding window size (300) is long, making the demand of learning temporal correlations even stronger.

    “On PAMAP dataset, we find that w/o TM performs particularly poorly, probably because its corresponding window size (300) is long, making the demand of learning temporal correlations even stronger.”
    Quote in the paperNot a substantial claim
  • Classified as probably not a substantial claim.

    Study design and conductnone given

    The final reported result is the average macro F1-score across five independent runs by varying seeds.

    “The final reported result is the average macro F1-score across five independent runs by varying seeds.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S4 (based). May combine two claims.

    Premisenone given

    Multi-device WHAR offers various benefits but also introduces the problem of missing devices, which is an inevitable and widespread issue.

    “Multi-device WHAR offers various benefits, but it also introduces the problem of missing devices.This is an inevitable and widespread issue.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning

    The decrease in performance for Realdisp may be due to overfitting as the network becomes more complex with an increasing number of layers.

    “This decrease in performance may be due to overfitting, as the network becomes more complex with an increasing number of layers.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning

    The slight improvement for RealWorld could be due to the larger size of RealWorld dataset, which can still be fit well with more layers.

    “This could be due to the larger size of RealWorld dataset, which can still be fit well with more layers.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S4 (based). May combine two claims.

    Premisenone given

    Previous SSL WHAR research has largely focused on single-device scenarios and has not considered the challenges and opportunities presented by multi-device data.

    “While previous research on SSL for WHAR has demonstrated promising results, these studies have largely focused on single-device scenarios and have not considered the challenges and opportunities presented by multi-device data.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationreasoning

    The Realdisp result can be attributed to the fine-grained nature of the fitness activities and the strong periodicity of the corresponding wearable data, allowing accurate reconstruction even at very high temporal masking probabilities.

    “This can be attributed to the fine-grained nature of the fitness activities in Realdisp dataset and the strong periodicity of the corresponding wearable data, allowing for accurate reconstruction of the time series even at very high temporal masking probabilities.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Interpretationown data

    The model is saturated with data and the current amount of data are sufficient for the model to fully exploit its potential.

    “suggesting that the model is saturated with data and that the current amount of data are sufficient for the model to fully exploit its potential.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationreasoning

    Without temporal masking, temporal correlations are not competently learned, so the parameters of TE cannot be learned well in pre-training phase.

    “This is because the structure of TE that corresponds to the temporal masking is Transformer encoders, which require sufficient learning to fully exploit the temporal correlations.Without the temporal masking, the temporal correlations are not competently learned, therefore the parameters of TE cannot be learned well in pre-training phase.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Interpretationreasoning

    The underwhelming performance of STMAE-Rand indicates the challenging nature of the activity recognition tasks undertaken and underscores the necessity for a proficient feature extractor.

    “The underwhelming performance of STMAE-Rand indicates the challenging nature of the activity recognition tasks we undertake, underscoring the necessity for a proficient feature extractor.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationreasoning

    The spatial masking corresponds to the SE (CNN structure), which has a small number of parameters and therefore has a smaller impact on the final performance.

    “The spatial masking corresponds to the SE (CNN structure), which has a small number of parameters and therefore has a smaller impact on the final performance.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given

    Lightweight downstream neural network structure is meaningful because supervised learning phase is usually done on edge but not on cloud.

    “Lightweight downstream neural network structure is meaningful, as supervised learning phase is usually done on edge but not on cloud.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S4 (based).

    Interpretationnone given

    If RD can recover the masked wearable values well, it means that the spatial and temporal encoders capture the spatial-temporal correlations well.

    “If RD can recover the masked wearable values well, it means that the spatial and temporal encoders capture the spatial-temporal correlations well.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S4 (based).

    Interpretationnone given

    Randomly selecting N_s out of N devices to mask all data from selected devices simulates the real-world scenario where some devices are not available during inference.

    “We randomly select 𝑁 s out of 𝑁 devices in each input sample such that all data from the selected devices are masked.This simulates the real-world scenario where some devices are not available during inference phase.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: It is impossible for every user to wear all devices at all time in daily life.
  • May combine two claims.

    Interpretationown data

    These computational costs are relatively low and meet the requirements for practical deployment.

    “These computational costs are relatively low and meet the requirements for practical deployment.”
    Quote in the paperSubstantial claim
  • Classified as probably not a substantial claim.

    Interpretationreasoning

    The labeled training data on RealWorld dataset are insufficient to fit the entire network structure of the encoders and classifier, which may explain the slight decrease in performance under the fine-tuned setting.

    “This may because the labeled training data on RealWorld dataset are insufficient to fit the entire network structure of the encoders and classifier.”
    Quote in the paperSubstantial claim
  • Classified as probably not a substantial claim.

    Interpretationreasoning

    The Transformer structure is capable of learning features more quickly and efficiently due to its parallel computation characteristic.

    “It achieves the best performance among the compared structures and is capable of learning features more quickly and efficiently due to its parallel computation characteristic.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing).

    Interpretationreasoning

    The specific number of applicable devices varies depending on the dataset and usage scenario.

    “The specific number of applicable devices varies depending on the dataset and usage scenario.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: Missing device scenarios are an inevitable problem for multi-device WHAR.
43 of 43
  • The paper relies on this without support.

    Wearable data require annotation at the time of data collection, unlike image or text data that can be annotated after collection.

    “Unlike image or text data that can be annotated through crowdsourcing or other means after data collection, wearable data require annotation at the time of data collection.”
  • The paper relies on this without support.

    It is impossible for every user to wear all devices at all time in daily life.

    “This situation is realistic, as it is impossible for every user to wear all devices at all time in daily life.”
  • The paper relies on this without support.

    Spatial correlations between data from various wearable devices differ depending on the activity being performed.

    “This is because the spatial correlations differ depending on the activity being performed.”
  • The paper relies on this without support.

    Spatial correlations can be utilized to infer data from one device based on data from other devices, making them a powerful means of reducing data redundancy.

    “These spatial correlations can also be utilized to infer data from one device based on the data from other devices, making them a powerful means of reducing data redundancy.”
  • The paper relies on this without support.

    Each device has a relatively small number of raw features (e.g., an IMU device typically contains raw features from a 3-axis accelerometer, a 3-axis gyroscope, and a 3-axis magnetometer).

    “Each device has a relatively small number of raw features.For example, an IMU device typically contains raw features from a 3-axis accelerometer, a 3-axis gyroscope, and a 3-axis magnetometer.”
  • The paper relies on this without support.

    Wearable data contain a relatively large number of temporal features and rich temporal context information; the time dimension is an order of magnitude larger than the spatial dimension.

    “However, wearable data contain a relatively large number of temporal features and rich temporal context information.For example, a 2-seconds input sample at a common sampling rate of 50 Hz contains 100 time points in the time dimension.It means that the features in the time dimension are an order of magnitude larger than those in the spatial dimension.”
  • The paper relies on this without support.

    Due to the high sampling rate of wearable devices (typically 50 Hz–200 Hz), raw readings at two adjacent time points have a strong similarity.

    “It is important to note that due to the high sampling rate of wearable devices (typically 50 Hz∼200 Hz), the raw readings at two adjacent time points have a strong similarity.”
  • The paper relies on this without support.

    Different activities exhibit different periodic patterns, amplitude ranges, etc., in time series.

    “Since different activities exhibit different periodic patterns, amplitude ranges, etc., in the time series, capturing temporal correlations is crucial to obtain features that can fully characterize the current activity.”
  • The paper relies on this without support.

    Missing device scenarios are an inevitable problem for multi-device WHAR.

    “We explore the performance of STMAE under missing device scenarios, which is an inevitable problem for multidevice WHAR.”
  • The paper relies on this without support.

    The four selected datasets enable a comprehensive and unbiased evaluation of the method.

    “These datasets have distinct characteristics in the number of subjects, the number of devices, the number and type of activities, and the sampling frequency, which opens the door to a comprehensive and unbiased evaluation of our method.”
10 of 10

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • The table reverses the stated labeling rates for RealWorld and Realdisp

    Major

    The experimental settings assign 1% labeled data to Realdisp and 10% to the other datasets. Table 2 instead assigns 1% to RealWorld and 10% to Realdisp, leaving the labeling rates behind the main comparison unclear.

  • The classifier input dimension does not match the TE output

    Minor

    The classifier is specified to take a D_rd-dimensional input, yet it directly receives the averaged TE output, which has dimension D_te. Table 3 sets these dimensions to 64 and 32, respectively, for PAMAP; they also differ for Opportunity and RealWorld.

  • RealWorld is not smaller than Realdisp

    Minor

    The text justifies Realdisp's lower labeling rate by saying the remaining datasets have much smaller sample sizes. Table 1 lists 39,281 RealWorld samples versus 6,280 Realdisp samples.

3 of 3

Cites

Flagged first, then by citations

Research works printed but not linked: 10

  1. Pierre Baldi. 2012. Autoencoders, unsupervised learning, and deep architectures. In Proceedings of ICML Workshop on Unsupervised and Transfer Learning. 37--49.
  2. Ting Chen, Simon Kornblith, Mohammad Norouzi, and Geoffrey Hinton. 2020. A simple framework for contrastive learning of visual representations. In Proceedings of the International Conference on Machine Learning. 1597--1607.
  3. Farhad Imani, Changqing Cheng, Ruimin Chen, and Hui Yang. 2018. Nested gaussian process modeling for high-dimensional data imputation in healthcare systems. In Proceedings of the IIE Annual Conference. 1312--1317.
  4. 10.1145/3432208 · DOI · Paper page
  5. Shizhan Liu, Hang Yu, Cong Liao, Jianguo Li, Weiyao Lin, Alex X Liu, and Schahram Dustdar. 2021. Pyraformer: Low-complexity pyramidal attention for long-range time series modeling and forecasting. In Proceedings of the International Conference on Learning Representations.
  6. Ashish Vaswani, Noam Shazeer, Niki Parmar, Jakob Uszkoreit, Llion Jones, Aidan N Gomez, Łukasz Kaiser, and Illia Polosukhin. 2017. Attention is all you need. In Proceedings of the Advances in Neural Information Processing Systems. 5998--6008.
  7. Haixu Wu, Jiehui Xu, Jianmin Wang, and Mingsheng Long. 2021. Autoformer: Decomposition transformers with auto-correlation for long-term series forecasting. Proceedings of the Advances in Neural Information Processing Systems, 22419--22430.
  8. Ling Yang and Shenda Hong. 2022. Unsupervised time-series representation learning with iterative bilinear temporal-spectral fusion. In International Conference on Machine Learning. PMLR, 25038--25054.
  9. Jinsung Yoon, James Jordon, and Mihaela Schaar. 2018. Gain: Missing data imputation using generative adversarial nets. In Proceedings of the International Conference on Machine Learning. 5689--5698.
  10. Jingguang Zhou and Zili Huang. 2018. Recover missing sensor data with iterative imputing network. In Proceedings of the Workshops at the AAAI Conference on Artificial Intelligence.

Cited by

Sorted by citations

Authors
Miao, S., Chen, L., & Hu, R.
Affiliations
Zhejiang University (CN)
Venue
Proceedings of the ACM on Interactive, Mobile, Wearable and Ubiquitous Technologies
Published
2023-12-19
Volume
7
Issue
4
Pages
1-25
ISSN
2474-9567 (ISSN-L)
OpenAlex
W4390821797
Cited by
23
References
63
Citations by year
2026: 3 · 2025: 9 · 2024: 11
FWCI
2.09
Type
journal article
Language
en
Open access
Locations
Proceedings of the ACM on Interactive Mobile Wearable and Ubiquitous Technologies (publishedVersion)
Topics
  • Physical Sciences › Computer Science › Computer Vision and Pattern Recognition › Context-Aware Activity Recognition Systems
  • Social Sciences › Transportation › Human Mobility and Location-Based Analysis
  • Health Sciences › Medicine › Physiology › Physical Activity and Health
Keywords
self-supervised learning, masked autoencoder, unlabeled data

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-11.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-11.

Cited sources are checked by gpt-6-sol.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review