Evaluating the Trustworthiness of Vision Language Models in Detecting Unsolvable Problems

Core Concepts

Vision language models often struggle to identify when a given visual question is unsolvable, leading to unreliable responses. This paper introduces the Unsolvable Problem Detection (UPD) challenge to assess a model's ability to withhold answers when faced with incompatible or irrelevant image-question pairs.

Abstract

This paper introduces the Unsolvable Problem Detection (UPD) challenge, which evaluates the ability of vision language models (VLMs) to recognize and refrain from answering unsolvable problems in the context of visual question answering (VQA) tasks.
The UPD challenge encompasses three distinct settings:

Absent Answer Detection (AAD): Evaluating the model's ability to recognize when the correct answer is not present in the provided options.
Incompatible Answer Set Detection (IASD): Assessing the model's capacity to identify situations where the answer choices are entirely irrelevant to the given context.
Incompatible Visual Question Detection (IVQD): Testing the model's understanding of the alignment between visual content and textual questions, and its ability to spot instances where the image and question are incompatible.

The authors create three benchmarks, MM-AAD Bench, MM-IASD Bench, and MM-IVQD Bench, based on the MMBench dataset, to systematically evaluate these UPD settings.
Experiments on five recent open-source VLMs and two close-source VLMs reveal that most models struggle to withhold answers even when faced with unsolvable problems, highlighting significant room for improvement. The authors explore both training-free (prompt engineering) and training-based (instruction tuning) approaches to address UPD, but find that notable challenges remain, particularly for smaller VLMs and in the AAD setting.
The paper emphasizes the importance of developing more trustworthy and reliable VLMs that can accurately identify and refrain from answering unsolvable problems, which is crucial for the safe and practical deployment of these models.

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Unsolvable Problem Detection

by Atsuyuki Miy... at arxiv.org 04-01-2024

https://arxiv.org/pdf/2403.20331.pdf

Deeper Inquiries

How can the UPD challenge be extended to other modalities beyond vision-language, such as audio-language or multimodal tasks involving speech?

The UPD challenge can be extended to other modalities beyond vision-language by adapting the core concept of detecting unsolvable problems to the specific characteristics of audio-language or multimodal tasks involving speech. For audio-language tasks, the model's ability to recognize and withhold answers when faced with unanswerable questions or irrelevant audio inputs can be evaluated. This could involve scenarios where the spoken question does not match the audio content provided, similar to the IVQD setting in the vision-language domain. In multimodal tasks involving speech, the challenge could focus on aligning spoken language with visual or textual information, assessing the model's capacity to identify discrepancies and refrain from providing inaccurate responses.

What are the potential biases or limitations in the current UPD benchmarks, and how can they be addressed to make the evaluation more comprehensive and representative?

One potential bias in the current UPD benchmarks could be the composition of the question-answer pairs and image-text combinations, which may not fully capture the diversity of unsolvable problems that VLMs may encounter in real-world applications. To address this, the benchmarks could be expanded to include a wider range of scenarios that challenge the model's ability to detect and refrain from answering unsolvable questions. Additionally, the benchmarks could be curated to include more nuanced and complex unsolvable problems, ensuring that the evaluation covers a comprehensive spectrum of challenges that VLMs may face.
Another limitation could be the reliance on automatic evaluation metrics, which may not fully capture the nuanced reasoning and decision-making processes involved in detecting unsolvable problems. To enhance the evaluation's comprehensiveness and representativeness, incorporating human judgment or expert evaluation could provide valuable insights into the model's performance in handling unsolvable tasks. This human-in-the-loop approach can offer qualitative feedback on the model's decision-making process and help identify areas for improvement in detecting and refraining from answering unsolvable problems.

Given the complexity of the UPD problem, what novel architectural or training approaches could be explored to significantly improve VLMs' ability to detect and refrain from answering unsolvable problems?

To enhance VLMs' ability to detect and refrain from answering unsolvable problems, novel architectural and training approaches can be explored:

Attention Mechanisms: Introducing specialized attention mechanisms that focus on identifying discrepancies between the image, question, and answer options can help the model better understand when a question is unsolvable. By attending to relevant parts of the input modalities, the model can learn to withhold answers in ambiguous or mismatched scenarios.

Meta-Learning: Leveraging meta-learning techniques to train VLMs on a diverse set of unsolvable problems can improve their generalization and adaptation capabilities. By exposing the model to a wide range of challenging scenarios during meta-training, it can learn to detect and handle unsolvable tasks more effectively.

Adversarial Training: Incorporating adversarial training strategies where the model is exposed to adversarially crafted unsolvable questions can enhance its robustness and resilience to misleading inputs. By training the model to recognize and avoid providing incorrect answers in adversarial settings, it can improve its performance on unsolvable problems.

Multi-Task Learning: Implementing multi-task learning frameworks that include specific tasks related to detecting and refraining from answering unsolvable questions can help VLMs develop specialized capabilities in handling such challenges. By jointly training the model on standard tasks and unsolvable problem detection tasks, it can learn to balance accuracy and caution in its responses.