Don't Buy it! Reassessing the Ad Understanding Abilities of Contrastive Multimodal Models
A. Bavaresco, A. Testoni, R. Fernández
TL;DR
This study scrutinizes automatic ad understanding by contrasting the original Pitt Ads retrieval setup with a grounded adversarial evaluation. It shows that zero-shot contrastive VLMs rely primarily on textual and visual grounding rather than deep multimodal reasoning, by using a carefully designed TRADE benchmark where adversarial explanations fool models but not humans. The authors demonstrate near-chance performance on TRADE across several VLMs and only modest gains on grounded control variants, while humans maintain high accuracy. The work highlights the need for robust evaluation protocols and suggests future work toward generative or differently calibrated assessments of multimodal ad understanding with careful control of grounding cues.
Abstract
Image-based advertisements are complex multimodal stimuli that often contain unusual visual elements and figurative language. Previous research on automatic ad understanding has reported impressive zero-shot accuracy of contrastive vision-and-language models (VLMs) on an ad-explanation retrieval task. Here, we examine the original task setup and show that contrastive VLMs can solve it by exploiting grounding heuristics. To control for this confound, we introduce TRADE, a new evaluation test set with adversarial grounded explanations. While these explanations look implausible to humans, we show that they "fool" four different contrastive VLMs. Our findings highlight the need for an improved operationalisation of automatic ad understanding that truly evaluates VLMs' multimodal reasoning abilities. We make our code and TRADE available at https://github.com/dmg-illc/trade .
