LaLa-World
Scaling Latent World Models
with Natural Language Actions
Junha Song1*Geonmo Gu1Jeongeun Park2Heejeong Nam3
Lucas Maes4Byeongho Heo1Dongyoon Han1Sangdoo Yun1†
1NAVER AI Lab2Georgia Institute of Technology
3Brown University4Mila & Université de Montréal
* Project lead† Corresponding author

01Background

World Models

What is a world model, and why do we need one?

  1. Background
  2. Motivation
  3. Our approach
  4. LaLa-World results
  5. LaLa-Policy results
  6. Looking ahead
01·Background

Acting and Imagining Together

Humans imagine what happens next while they act.

Now
Push right
World model
Imagine one step
Keep
pushing
Imagine two steps
falls!
World-model research aims to give machines this ability.
01·Background

What Is a World Model?

An actor chooses an action.

A world model imagines what happens next.

A critic evaluates the imagined outcome.

DreamerV3, MuZero, TD-MPC2

World model
Critic
  • [Hafner et al., 'Mastering Diverse Control Tasks through World Models']
  • [Schrittwieser et al., 'Mastering Atari, Go, Chess and Shogi by Planning with a Learned Model']
  • [Hansen et al., 'TD-MPC2: Scalable, Robust World Models for Continuous Control']
01·Background

JEPA-Style Latent World Models

Learn to predict future representations without game-reward supervision.

DINO-WM, V-JEPA 2-AC, LeWorldModel
Our focus
Future latent
Future predictor
Current latent + action
  • [Zhou et al., 'DINO-WM: World Models on Pre-trained Visual Features enable Zero-shot Planning']
  • [Assran et al., 'V-JEPA 2: Self-Supervised Video Models Enable Understanding, Prediction and Planning']
  • [Maes et al., 'LeWorldModel: Stable End-to-End Joint-Embedding Predictive Architecture from Pixels']
01·Background

The Data behind Latent World Models

Current observation, numerical action, future observation.

Current observation
Numerical action
[0.81, 0.84, −1.46, −0.08, …]
Future observation
01·Background

The Usual Numerical-Action Predictor

Visual tokens and embedded numerical actions condition a Transformer.

The action interface and training data define the supported domains.

Vision encoder
[0.81, 0.84, −1.46, −0.08]
Numerical vector
Action MLP
Transformer predictor
Future latent
Typically trained on
1
Control data only
2
A fixed set of domains
01·Background

Actions Differ across Domains

Vector size and physical meaning both change.

Domain
Numerical action
Push-T
2-D displacement
[−0.60, −1.95]
PointMaze
2-D force
[0.50, 0.46]
MetaWorld
4-D position + grip
[0.81, 0.84, −1.46, −0.08]
DROID
7-D pose + gripper
[0.5, 0.6, 5.9, 2, −7, …]
OpenVid
Web video
No numerical action label
Predictor for Push-T
Predictor for PointMaze
Predictor for MetaWorld
Predictor for DROID

02Motivation

Generative World Models

Language connects broad visual pretraining to policy learning.

  1. Background
  2. Motivation
  3. Our approach
  4. LaLa-World results
  5. LaLa-Policy results
  6. Looking ahead
02·Motivation

What We Mean by Generative World Models

Video generation models, such as Cosmos-Predict2, generate future frames from the current frame and a text prompt.

The hand stirs the
liquid in the cup.
Current frame
Text prompt
Video noise
  • [Ali et al., 'World Simulation with Video Foundation Models for Physical AI']
02·Motivation

Language Describes Visual Change

Video generation models learn from diverse images and videos.

Video transition
The hand stirs the liquid in the cup.
Edit
Swap the moon with a vibrant sunset.
  • [Nan et al., 'OpenVid-1M: A Large-Scale High-Quality Dataset for Text-to-Video Generation']
  • [Wei et al., 'OmniEdit: Building Image Editing Generalist Models through Specialist Supervision']
02·Motivation

A Broad Visual Prior

Language makes heterogeneous visual data usable in a shared prediction task.

02·Motivation

Video Pretraining Can Support Policy Learning

Cosmos-Predict2 predicts future video.

Cosmos Policy learns actions and their visual consequences.

Observation + task + proprioception
Video noise
Policy fine-tuning
Observation + task + proprioception
Video noise
Action noise
Action chunk
  • [Ali et al., 'World Simulation with Video Foundation Models for Physical AI']
  • [Kim et al., 'Cosmos Policy: Fine-Tuning Video Models for Visuomotor Control and Planning']

03Our approach

LaLa-World

The same transfer idea, with future prediction in latent space.

  1. Background
  2. Motivation
  3. Our approach
  4. LaLa-World results
  5. LaLa-Policy results
  6. Looking ahead
03·Our approach

Language as a Shared Action Interface

Keep direction and magnitude while expressing actions in words.

The same format also describes visual change in web data.

All domains condition one future predictor through language.

Domain
Numerical action
Our idea: say every action in words
Push-T
2-D displacement
[−0.60, −1.95]
[−0.60, −1.95]
Move the pusher 0.60 left
and 1.95 down.
PointMaze
2-D force
[0.50, 0.46]
[0.50, 0.46]
Push the ball with force
0.50 right and 0.46 up.
MetaWorld
4-D position + grip
[0.81, 0.84, −1.46, −0.08]
[0.81, 0.84, −1.46, −0.08]
Move the gripper 0.81 right, 0.84 forward,
1.46 down and loosen the grip by 0.08.
DROID
7-D pose + gripper
[0.5, 0.6, 5.9, 2, −7, …]
[0.5, 0.6, 5.9, 2, −7, …]
Move gripper 0.5 cm forward, 0.6 cm right,
5.9 cm up; rotate roll +2°, pitch −7°, …
OpenVid
Web video
No numerical action label
No numerical action label
The hand stirs the liquid in the cup
with the spoon, creating a swirling motion.
z
language condition
Predictor for
multiple domains
03·Our approach

Scaling Training Data for Latent World Models

A shared prediction task can absorb increasingly diverse visual data.

Generative WMs
Prior latent WMs
LaLa-World
Diverse images & videos
Fixed-domain control data
Multi-domain control data
Diverse images & videos
03·Our approach

LaLa-World Architecture

Encode observations into visual representations.

A language model reads the condition alongside visual tokens.

Visual encoderfrozen
Task instruction
Future queries
Pretrained LM predictorQwen3.5-0.8B
Future latent
Visual encoderfrozen
target
  • [Qwen Team, 'Qwen3.5: Towards Native Multimodal Agents']
03·Our approach

Fine-Tuning LaLa-World into LaLa-Policy

Reuse the pretrained future predictor.

An action generator denoises noise into a robot action chunk.

Visual encoderfrozen
Task instruction
Future queries
Pretrained LM predictorQwen3.5-0.8B
LaLa-Policy
Future latent
noise
Action chunk
  • [Qwen Team, 'Qwen3.5: Towards Native Multimodal Agents']

04Results

LaLa-World Results

Does the predicted future help us choose useful actions?

  1. Background
  2. Motivation
  3. Our approach
  4. LaLa-World results
  5. LaLa-Policy results
  6. Looking ahead
04·LaLa-World results

Planning toward a Goal Image

Given an initial state and a goal, find an action sequence.

Initial observation
Goal observation
Which action sequence?
04·LaLa-World results

Sampling Candidate Sequences

Imagining Candidate Futures

Latent Goal Comparison

MPC Executes, Observes, and Replans

Draw action sequences and express each one in language.

Roll out the latent world model for each sequence.

Rank candidates by the L2 distance in latent space.

Keep the best candidates, refit, and sample again.

Current
Candidate sequences
[a1, a2, a3, …]
[b1, b2, b3, …]
[c1, c2, c3, …]
LaLa-World
Imagined futures
Goal
Encoder
L2 distance
far
closest
far
Refit distribution
Resample sequences
  • [Rubinstein, 'Optimization of Computer Simulation Models with Rare Events']
04·LaLa-World results

Planning across Five Shared Benchmarks

LaLa-World achieves the highest average success rate.

Average success rate (%)
0
20
40
60
80
100
LaLa-World
72.1
JEPA-WMs
64.6
DINO-WM
62.3
LeWorldModel
28.1
Wall
PointMaze
Push-T
MetaWorld-R
MetaWorld-RW
  • [Terver et al., 'What Drives Success in Physical Planning with Joint-Embedding Predictive World Models?']
  • [Zhou et al., 'DINO-WM: World Models on Pre-trained Visual Features enable Zero-shot Planning']
  • [Maes et al., 'LeWorldModel: Stable End-to-End Joint-Embedding Predictive Architecture from Pixels']
04·LaLa-World results

Selected Actions in Wall

Numerical language actions

1.4×
  • [Zhou et al., 'DINO-WM: World Models on Pre-trained Visual Features enable Zero-shot Planning']
04·LaLa-World results

Selected Actions in Push-T

Numerical language actions

1.4×
  • [Chi et al., 'Diffusion Policy: Visuomotor Policy Learning via Action Diffusion']
04·LaLa-World results

Selected Actions in PointMaze

Qualitative language actions

1.4×
  • [Fu et al., 'D4RL: Datasets for Deep Data-Driven Reinforcement Learning']
04·LaLa-World results

Selected Actions in Rope

Qualitative language actions

1.4×
  • [Zhang et al., 'AdaptiGraph: Material-Adaptive Graph-Based Neural Dynamics for Robotic Manipulation']

05Results

LaLa-Policy Results

Does latent world-model pretraining improve action prediction?

  1. Background
  2. Motivation
  3. Our approach
  4. LaLa-World results
  5. LaLa-Policy results
  6. Looking ahead
05·LaLa-Policy results

How the Policy Recipes Differ

VLAs predict actions, but not their consequences

VLA
observation
+ instruction
VLA
actions
outcome ?
Actions only
the outcome of the action is never predicted
Humans
imagined outcome
an image, or a latent
Action + imagined consequence
we foresee the result of the force we apply
  • [Physical Intelligence et al., ': a Vision-Language-Action Model with Open-World Generalization']
  • [Li et al., 'CogVLA: Cognition-Aligned Vision-Language-Action Model via Instruction-Driven Routing & Sparsification']
05·LaLa-Policy results

How the Policy Recipes Differ

The initialization and prediction targets distinguish these representative models.

PolicyInitializationJoint prediction
VLAPretrained VLMAction chunk
Cosmos PolicyCosmos-Predict2Action chunk + future frames
LaLa-PolicyLaLa-WorldAction chunk + future latents
  • [Physical Intelligence et al., ': a Vision-Language-Action Model with Open-World Generalization']
  • [Li et al., 'CogVLA: Cognition-Aligned Vision-Language-Action Model via Instruction-Driven Routing & Sparsification']
  • [Kim et al., 'Cosmos Policy: Fine-Tuning Video Models for Visuomotor Control and Planning']
  • [Ali et al., 'World Simulation with Video Foundation Models for Physical AI']
05·LaLa-Policy results

World-Model Pretraining Transfers to Policy Learning

LaLa-Policy is competitive with strong VLA and video-policy baselines.

RoboCasa success rate (%)
50
52
54
56
58
60
LaLa-Policy from
LaLa-World
57.3
LaLa-Policy from
Random Init
55.5
Cosmos Policy
56.0
MolmoAct2
54.3
54.5
+1.8
from LaLa-World pretraining
  • [Physical Intelligence et al., ': a Vision-Language-Action Model with Open-World Generalization']
  • [Fang et al., 'MolmoAct2: Action Reasoning Models for Real-World Deployment']
  • [Kim et al., 'Cosmos Policy: Fine-Tuning Video Models for Visuomotor Control and Planning']
  • [Nasiriany et al., 'RoboCasa: Large-Scale Simulation of Everyday Tasks for Generalist Robots']
05·LaLa-Policy results

Faster Policy Inference

LaLa-Policy predicts future latents while keeping action performance competitive.

RoboCasa · model inference time
0
2
4
6
8
10
12
14
seconds per trajectory · lower is better
LaLa-Policy
2.12 s
Cosmos Policy
11.71 s
5.5×
faster
  • [Kim et al., 'Cosmos Policy: Fine-Tuning Video Models for Visuomotor Control and Planning']
  • [Nasiriany et al., 'RoboCasa: Large-Scale Simulation of Everyday Tasks for Generalist Robots']
05·LaLa-Policy results

Acting and Anticipating Together

The policy jointly predicts an action chunk and a future latent.

Observation + instruction
LaLa-Policy
Consequence
in latent space
05·LaLa-Policy results

Acting and Anticipating Together

The video compares execution with a prediction made earlier.

Decoded predicted futures
05·LaLa-Policy results

LIBERO: Bowl to Plate

“Pick up the black bowl on the ramekin and place it on the plate.”

Decoded future
  • [Liu et al., 'LIBERO: Benchmarking Knowledge Transfer for Lifelong Robot Learning']
05·LaLa-Policy results

LIBERO: Bowl to Cabinet

“Put the bowl on top of the cabinet.”

Decoded future
  • [Liu et al., 'LIBERO: Benchmarking Knowledge Transfer for Lifelong Robot Learning']
05·LaLa-Policy results

RoboCasa: Serve Coffee

“Press the button on the coffee machine to serve coffee.”

Decoded future
  • [Nasiriany et al., 'RoboCasa: Large-Scale Simulation of Everyday Tasks for Generalist Robots']
05·LaLa-Policy results

RoboCasa: Open the Microwave

“Open the microwave door.”

Decoded future
  • [Nasiriany et al., 'RoboCasa: Large-Scale Simulation of Everyday Tasks for Generalist Robots']

06Looking ahead

Future Directions

Scaling latent world models and connecting them to agents.

  1. Background
  2. Motivation
  3. Our approach
  4. LaLa-World results
  5. LaLa-Policy results
  6. Looking ahead
06·Looking ahead

Extending the Current Work

Test whether the gains transfer to real robots.

01
Scale data
and model
02
Learn the encoder
end-to-end
03
Evaluate on
real robots
Larger predictor
Predictor
Vision encoder
Stable joint learning
Generalization in deployment
06·Looking ahead

Robotics Grows with Agents

My hypothesis: robotics can grow as rapidly as AI agents.

A request
Attempt 01
Attempt 02
A system that acts, observes, and improves
06·Looking ahead

Research Questions at the Agent–Robot Interface

Where can a latent world model be most useful?

Benchmarks
Evaluate long tasks and repeated attempts
World models
Anticipate outcomes before execution
Long-context memory
Retain experience across tasks
Self-improving systems
Improve through repeated attempts
Thank You
Junha Song

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