LG-CAV: Train Any Concept Activation Vector with Language Guidance

Concept activation vector (CAV) has attracted broad research interest in explainable AI, by elegantly attributing model predictions to specific concepts. However, the training of CAV often necessitates a large number of high-quality images, which are expensive to curate and thus limited to a predefined set of concepts. To address this issue, we propose Language-Guided CAV (LG-CAV) to harness the abundant concept knowledge within the certain pre-trained vision-language models (e.g., CLIP). This method allows training any CAV without labeled data, by utilizing the corresponding concept descriptions as guidance. To bridge the gap between vision-language model and the target model, we calculate the activation values of concept descriptions on a common pool of images (probe images) with vision-language model and utilize them as language guidance to train the LG-CAV. Furthermore, after training high-quality LG-CAVs related to all the predicted classes in the target model, we propose the activation sample reweighting (ASR), serving as a model correction technique, to improve the performance of the target model in return. Experiments on four datasets across nine architectures demonstrate that LG-CAV achieves significantly superior quality to previous CAV methods given any concept, and our model correction method achieves state-of-the-art performance compared to existing concept-based methods. Our code is available at https://github.com/hqhQAQ/LG-CAV.

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Peer review

Reviewer sN5p6/10 · confidence 4/52024-07-02

Summary

This paper proposed a LG-CAV model that leverage the pretrained vision language model to train CAV without label. This includes a concept ensemble model that employ data augmentation on concept text, a DSR module that optmize the selection of probe image and a model to align prediction of class to concepts called ASR. Experiments showed that this framework achives higher CAV quality.

Strengths

The methodology is carried out clearly. The problem is important and the authors have got some good results. The experiments show its proposed model’s effectiveness.

Weaknesses

1.Since LG-CAV leverage pretrained model, I am wondering whether this framework can handle unseen class besides just supervised setting such as novel category detection/generalized category detection. For example, instead of pick 40 classes from ImageNet, could you use 20 for training and the other 20 for testing? 2. From figure 5 we can see that not all concepts are related to the input sentence. I am curious how the similarity threshold is selected. 3. Evaluation of concept-to-class accuracy will need human evaluation of concept. How this is done in detail? 4. From Table 4, the improvement compare with LG-CAV and other baseline is limited.

Questions

see the weaknesses

Rating

6

Confidence

4

Soundness

3

Presentation

3

Contribution

3

Limitations

NA

Reviewer TRvX7/10 · confidence 5/52024-07-08

Summary

This paper proposes LG-CAV, a method to train Concept Activation Vectors (CAVs) for any concept without labeled image data, leveraging knowledge from pre-trained vision-language models like CLIP. The authors introduce several techniques to improve CAV quality, including Gaussian alignment, concept ensemble, and deviation sample reweighting. They also propose using the trained LG-CAVs for model correction to improve classification performance. Experiments demonstrate superior CAV quality and model correction results compared to existing methods across multiple datasets and model architectures.

Strengths

1. This paper is well written. The framework is integral, and every component is clearly described in detail. The whole pipeline is easy to follow. 2. The authors propose a novel method with feature alignment loss functions and neural modules to bridge the gap between pre-trained vision-language models and the target classification model. 3. The experimental results show the proposed method achieves the best performance. 4. This paper introduces two new metrics (concept accuracy and concept-to-class accuracy) to evaluate CAV quality. These two metrics are reasonable.

Weaknesses

1. Some of the proposed modules (e.g., Gaussian alignment) seem heuristic. It would be better to give some theoretical justifications. 2. The method uses a set of probe images, but it's not clear how to ensure that the trained LG-CAVs generalize beyond these images.

Questions

No specific questions. This work is of high completeness.

Rating

7

Confidence

5

Soundness

3

Presentation

4

Contribution

3

Limitations

No specific limtations. This work is of high completeness.

Reviewer V8uU5/10 · confidence 3/52024-07-10

Summary

The paper introduces Language-Guided Concept Activation Vectors (LG-CAV), a method to train Concept Activation Vectors (CAVs) without labeled data by leveraging pre-trained vision-language models such as CLIP. LG-CAV uses concept descriptions to guide the training of CAVs by aligning the activation values of concept descriptions on a set of probe images. To improve the quality of LG-CAVs, the authors propose three modules: Gaussian Alignment (GA), Concept Ensemble (CE), and Deviation Sample Reweighting (DSR). The paper also introduces an Activation Sample Reweighting (ASR) technique for model correction, which enhances the performance of the target model. Experiments across various datasets and architectures demonstrate that LG-CAV outperforms existing CAV methods in terms of concept accuracy and concept-to-class accuracy.

Strengths

1. The paper is well-written. 2. The use of vision-language models allows for training CAVs without the need for labeled data. 3. The introduction of GA, CE, and DSR modules improves the quality of LG-CAVs. 4. Beyond generating explanations, the method is applied to model correction, leading to improved performance in target models. 5. The results show substantial improvements in both concept accuracy and concept-to-class accuracy compared to existing methods.

Weaknesses

1. The method proposed in this paper does not clearly address the data scarcity problem of the original CAV methods, which was highlighted at the beginning. Although the method is effective, it is not evident why it successfully addresses the data scarcity issue. 2. The method heavily relies on the availability and performance of pre-trained vision-language models like CLIP, which may not always be accessible or optimal for all tasks. 3. The introduction of multiple enhancement modules increases the complexity and computational requirements of the method, which may be a barrier to practical applications. 4. The paper could benefit from a more detailed analysis of scenarios where LG-CAV does not perform well or fails to improve over traditional methods.

Questions

1. Equation 3 uses cosine similarity to calculate the activation values because cosine similarity is invariant to the norms of feature vectors as claimed by the authors. However, this reasoning does not convincingly explain why cosine similarity is necessary in this context. 2. Additionally, in lines 153-155, the authors state that "compared with the original binary classification task for CAV training, the activation values encompass richer information about the extent to which the concepts exist in the images, thus facilitating the training of LG-CAV." I question why richer information can be obtained here. Is there any empirical evidence to support this claim? 3. How does the performance of LG-CAV vary with different types and sizes of pre-trained vision-language models beyond CLIP? 4. What are the computational costs and training times associated with the LG-CAV method compared to traditional CAV methods?

Rating

5

Confidence

3

Soundness

2

Presentation

3

Contribution

2

Limitations

See above.

Program Chairsdecision2024-09-25

Decision

Accept (poster)

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