  Can we better anticipate an actor's future actions (e.g. mix eggs) by knowing
what commonly happens after his/her current action (e.g. crack eggs)? What if
we also know the longer-term goal of the actor (e.g. making egg fried rice)?
The long-term action anticipation (LTA) task aims to predict an actor's future
behavior from video observations in the form of verb and noun sequences, and it
is crucial for human-machine interaction. We propose to formulate the LTA task
from two perspectives: a bottom-up approach that predicts the next actions
autoregressively by modeling temporal dynamics; and a top-down approach that
infers the goal of the actor and plans the needed procedure to accomplish the
goal. We hypothesize that large language models (LLMs), which have been
pretrained on procedure text data (e.g. recipes, how-tos), have the potential
to help LTA from both perspectives. It can help provide the prior knowledge on
the possible next actions, and infer the goal given the observed part of a
procedure, respectively. To leverage the LLMs, we propose a two-stage
framework, AntGPT. It first recognizes the actions already performed in the
observed videos and then asks an LLM to predict the future actions via
conditioned generation, or to infer the goal and plan the whole procedure by
chain-of-thought prompting. Empirical results on the Ego4D LTA v1 and v2
benchmarks, EPIC-Kitchens-55, as well as EGTEA GAZE+ demonstrate the
effectiveness of our proposed approach. AntGPT achieves state-of-the-art
performance on all above benchmarks, and can successfully infer the goal and
thus perform goal-conditioned "counterfactual" prediction via qualitative
analysis. Code and model will be released at
https://brown-palm.github.io/AntGPT
