  Multimodal event argument role labeling (EARL), a task that assigns a role
for each event participant (object) in an image is a complex challenge. It
requires reasoning over the entire image, the depicted event, and the
interactions between various objects participating in the event. Existing
models heavily rely on high-quality event-annotated training data to understand
the event semantics and structures, and they fail to generalize to new event
types and domains. In this paper, we propose GenEARL, a training-free
generative framework that harness the power of the modern generative models to
understand event task descriptions given image contexts to perform the EARL
task. Specifically, GenEARL comprises two stages of generative prompting with a
frozen vision-language model (VLM) and a frozen large language model (LLM).
First, a generative VLM learns the semantics of the event argument roles and
generates event-centric object descriptions based on the image. Subsequently, a
LLM is prompted with the generated object descriptions with a predefined
template for EARL (i.e., assign an object with an event argument role). We show
that GenEARL outperforms the contrastive pretraining (CLIP) baseline by 9.4%
and 14.2% accuracy for zero-shot EARL on the M2E2 and SwiG datasets,
respectively. In addition, we outperform CLIP-Event by 22% precision on M2E2
dataset. The framework also allows flexible adaptation and generalization to
unseen domains.
