  We introduce a new task called Referring Atomic Video Action Recognition
(RAVAR), aimed at identifying atomic actions of a particular person based on a
textual description and the video data of this person. This task differs from
traditional action recognition and localization, where predictions are
delivered for all present individuals. In contrast, we focus on recognizing the
correct atomic action of a specific individual, guided by text. To explore this
task, we present the RefAVA dataset, containing 36,630 instances with manually
annotated textual descriptions of the individuals. To establish a strong
initial benchmark, we implement and validate baselines from various domains,
e.g., atomic action localization, video question answering, and text-video
retrieval. Since these existing methods underperform on RAVAR, we introduce
RefAtomNet -- a novel cross-stream attention-driven method specialized for the
unique challenges of RAVAR: the need to interpret a textual referring
expression for the targeted individual, utilize this reference to guide the
spatial localization and harvest the prediction of the atomic actions for the
referring person. The key ingredients are: (1) a multi-stream architecture that
connects video, text, and a new location-semantic stream, and (2) cross-stream
agent attention fusion and agent token fusion which amplify the most relevant
information across these streams and consistently surpasses standard
attention-based fusion on RAVAR. Extensive experiments demonstrate the
effectiveness of RefAtomNet and its building blocks for recognizing the action
of the described individual. The dataset and code will be made publicly
available at https://github.com/KPeng9510/RAVAR.
