You and a buddy are going to play “next word”, but it’s probably already known by a better name than I made up.
You start with one word, ANY word at all, and say it out loud, then your buddy says the next word in the yet unknown sentence, then it’s back to you for one word. Loop until you hit an end.
Let’s say you start with “You”. Then your buddy says the next word out loud, also whatever they want. Let’s go with “are”. Then back to you for the next word, “smarter” -> “than” -> “you” -> “think.”
Neither of you knew what you were going to say, you only knew what was just said so you picked a reasonable next word. There was no ‘thought’, only next token prediction, and yet magically the final output was coherent. If you want to really get into the LLM simulation game then have a third person provide the first full sentence, then one of you picks up the first word in the next sentence and you two continue from there. As soon as you hit a breaking point the third person injects another full sentence and you two continue the game.
With no idea what either of you are going to say and no clue about what the end result will be, no thought or reasoning at all, it won’t be long before you’re sounding super coherent while explaining thermodynamics. But one of the rounds someone’s going to mess it up, like “gluons” -> “weigh” -> “…more?…” -> “…than…(damnit Gary)…” but you must continue the game and finish the sentence, then sit back and think about how you just hallucinated an answer without thinking, reasoning, understanding, or even knowing what you were saying until it finished.
“that’s not how cow work. study bovine theory. contraction of expiratory musculature elevates abdominal pressure and reduces thoracic volume, generating positive subglottal pressure…”
> or, to the extent they do, this world model is solely based on token patterns
Obviously not true because of RL environments.
There obviously is in humans. When you visually simulate things or e.g. simulate how food will taste in your mind as you add different seasonings, you are modeling (part of) the world. This is presumably done by having associations in our brain between all the different qualia sequences and other kinds of representations in our mind. I.e. we know we do some visuospatial reasoning tasks using sequences of (imagined) images. Imagery is one aspect of our world model(s).
We know LLMs can't be doing visuospatial reasoning using imagery, because they only work with text tokens. A VLM or other multimodal might be able to do so, but an LLM can't, and so an LLM can't have a visual world model. They might in special cases be able to construct a linguistic model that lets them do some computer vision tasks, but the model will itself still only be using tokenized words.
There are all sorts of other sensory modalities and things that humans use when thinking (i.e. actual logic and reasoning, which goes beyond mere semantics and might include things like logical or other forms of consistency, e.g. consistency with a relevant mental image), and the "world model" concept is supposed, in part, to point to these things that are more than just language and tokens.
> Obviously not true because of RL environments.
Right, AI generally can have much more complex world models than LLMs. An LLM can't even handle e.g. sensor data without significant architectural and training modification (https://news.ycombinator.com/item?id=46948266), at which point, it is no longer an LLM.
Modeling something as an action is not "having a world model". A model is a consistently existing thing, but humans don't construct consistently existing models because it'd be a waste of time. You don't need to know what's in your trash in order to take the trash bags out.
> We know LLMs can't be doing visuospatial reasoning using imagery, because they only work with text tokens.
All frontier LLMs are multimodal to some degree. ChatGPT thinking uses it the most.
It literally is, this is definitional. See e.g. how these terms are used in e.g. the V-JEPA-2 paper (https://arxiv.org/pdf/2506.09985). EDIT: Maybe you are unaware of what the term means and how it is used, it does not mean "a model of all of reality", i.e. we don't have a single world model, but many world models that are used in different contexts.
> A model is a consistently existing thing, but humans don't construct consistently existing models because it'd be a waste of time. You don't need to know what's in your trash in order to take the trash bags out.
Both sentences are obviously just completely wrong here. I need to know what is in my trash, and how much, to decide if I need to take it out, and how heavy it is may change how I take it out too. We construct models all the time, some temporary and forgotten, some which we hold within us for life.
> All frontier LLMs are multimodal to some degree. ChatGPT thinking uses it the most.
LLMs by definition are not multimodal. Frontier models are multimodal, but only in a very weak and limited sense, as I address in e.g. other comments (https://news.ycombinator.com/item?id=46939091, https://news.ycombinator.com/item?id=46940666). For the most part, none of the text outputs you get from a frontier model are informed by or using any of the embeddings or semantics learned from images and video (in part due to lack of data and cost of processing visual data), and only certain tasks will trigger e.g. the underlying VLMs. This is not like humans, where we use visual reasoning and visual world models constantly (unless you are a wordcel).
And most VLM architectures are multi-modal in a very limited or simplistic way still, with lots of separately pre-trained backbones (https://huggingface.co/blog/vlms-2025). Frontier models are nowhere near being even close to multimodal in the way that human thinking and reasoning is.
I put "token" in quotes because this would obviously not necessarily be an explicit token, but it would have to be learned group of tokens, for example. But who knows, if the thinking models have some weird pseudo-xml delimiters for thinking, it's not crazy to think that an LLM could shove this information in say the closer tag.
If it wasn't clear, I am talking about LLMs in use today, not ultimate capabilities. All commercial models are known (or believed) to be recursively applied transformers without e.g. backspace or "tombstone" tokens, like you are mentioning here.
But yes, absolutely LLMs might someday be able to backtrack, either literally during token generation if we allow e.g. backspace tokens (there was at least one paper that did this) or more broadly at the chain of thought level, with methods like you are mentioning.
Current LLM implementations cannot delete output text, i.e. they cannot remove text from their context window. The recursive application is such that outputs are always expanding what is in the window, so there is no backtracking like humans can do, i.e. "this text was bad, ignore it and remove from context". That's part of why we got crazy loops / spirals like we did with the "show me the seahorse emoji" prompts.
Backtracking needs more than just a special token or cluster of tokens, but also for the LLM behaviour to be modified when it sees that token or token cluster. This must be manually coded in, it cannot be learned.