Do Vision & Language Decoders use Images and Text equally? How Self-consistent are their Explanations?

Fuente: arXiv
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Main Authors: Parcalabescu, Letitia, Frank, Anette
Format: Preprint
Published: 2024
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author Parcalabescu, Letitia
Frank, Anette
author_facet Parcalabescu, Letitia
Frank, Anette
contents Vision and language model (VLM) decoders are currently the best-performing architectures on multimodal tasks. Next to answers, they are able to produce natural language explanations, either in post-hoc or CoT settings. However, it is not clear to what extent they are using the input vision and text modalities when generating answers or explanations. In this work, we investigate if VLMs rely on their input modalities differently when they produce explanations as opposed to answers. We also evaluate the self-consistency of VLM decoders in both post-hoc and CoT explanation settings, by extending existing unimodal tests and measures to VLM decoders. We find that most tested VLMs are less self-consistent than LLMs. Text contributions in all tested VL decoders are more important than image contributions in all examined tasks. However, when comparing explanation generation to answer generation, the contributions of images are significantly stronger for generating explanations compared to answers. This difference is even larger in CoT compared to post-hoc explanations. Lastly, we provide an up-to-date benchmarking of state-of-the-art VL decoders on the VALSE benchmark, which before was restricted to VL encoders. We find that the tested VL decoders still struggle with most phenomena tested by VALSE.
format Preprint
id arxiv_https___arxiv_org_abs_2404_18624
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Do Vision & Language Decoders use Images and Text equally? How Self-consistent are their Explanations?
Parcalabescu, Letitia
Frank, Anette
Computation and Language
Artificial Intelligence
Computer Vision and Pattern Recognition
Machine Learning
68Txx
I.2.7; I.2.10
Vision and language model (VLM) decoders are currently the best-performing architectures on multimodal tasks. Next to answers, they are able to produce natural language explanations, either in post-hoc or CoT settings. However, it is not clear to what extent they are using the input vision and text modalities when generating answers or explanations. In this work, we investigate if VLMs rely on their input modalities differently when they produce explanations as opposed to answers. We also evaluate the self-consistency of VLM decoders in both post-hoc and CoT explanation settings, by extending existing unimodal tests and measures to VLM decoders. We find that most tested VLMs are less self-consistent than LLMs. Text contributions in all tested VL decoders are more important than image contributions in all examined tasks. However, when comparing explanation generation to answer generation, the contributions of images are significantly stronger for generating explanations compared to answers. This difference is even larger in CoT compared to post-hoc explanations. Lastly, we provide an up-to-date benchmarking of state-of-the-art VL decoders on the VALSE benchmark, which before was restricted to VL encoders. We find that the tested VL decoders still struggle with most phenomena tested by VALSE.
title Do Vision & Language Decoders use Images and Text equally? How Self-consistent are their Explanations?
topic Computation and Language
Artificial Intelligence
Computer Vision and Pattern Recognition
Machine Learning
68Txx
I.2.7; I.2.10
url https://arxiv.org/abs/2404.18624