When are Lemons Purple? The Concept Association Bias of Vision-Language Models

Yingtian Tang, Yutaro Yamada, Yoyo Zhang, Ilker Yildirim


Abstract
Large-scale vision-language models such as CLIP have shown impressive performance on zero-shot image classification and image-to-text retrieval. However, such performance does not realize in tasks that require a finer-grained correspondence between vision and language, such as Visual Question Answering (VQA). We investigate why this is the case, and report an interesting phenomenon of vision-language models, which we call the Concept Association Bias (CAB), as a potential cause of the difficulty of applying these models to VQA and similar tasks. We find that models with CAB tend to treat input as a bag of concepts and attempt to fill in the other missing concept crossmodally, leading to an unexpected zero-shot prediction. We demonstrate CAB by showing that CLIP’s zero-shot classification performance greatly suffers when there is a strong concept association between an object (e.g. eggplant) and an attribute (e.g. color purple). We also show that the strength of CAB predicts the performance on VQA. We observe that CAB is prevalent in vision-language models trained with contrastive losses, even when autoregressive losses are jointly employed. However, a model that solely relies on autoregressive loss seems to exhibit minimal or no signs of CAB.
Anthology ID:
2023.emnlp-main.886
Volume:
Proceedings of the 2023 Conference on Empirical Methods in Natural Language Processing
Month:
December
Year:
2023
Address:
Singapore
Editors:
Houda Bouamor, Juan Pino, Kalika Bali
Venue:
EMNLP
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
14333–14348
Language:
URL:
https://aclanthology.org/2023.emnlp-main.886
DOI:
10.18653/v1/2023.emnlp-main.886
Bibkey:
Cite (ACL):
Yingtian Tang, Yutaro Yamada, Yoyo Zhang, and Ilker Yildirim. 2023. When are Lemons Purple? The Concept Association Bias of Vision-Language Models. In Proceedings of the 2023 Conference on Empirical Methods in Natural Language Processing, pages 14333–14348, Singapore. Association for Computational Linguistics.
Cite (Informal):
When are Lemons Purple? The Concept Association Bias of Vision-Language Models (Tang et al., EMNLP 2023)
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PDF:
https://aclanthology.org/2023.emnlp-main.886.pdf
Video:
 https://aclanthology.org/2023.emnlp-main.886.mp4