Situated language learning

Update: this content (and more) is now available as a more thorough abstract on arXiv, co-authored with my OpenAI colleague Igor Mordatch.

I’ve been really pleased with the response to my last post, On “solving language.” While I certainly wasn’t saying anything revolutionary, it does seem that I managed to capture some very common sentiment floating around in the AI community today. I think the post has served as a clear checkpoint for me and for people with similar interests: it’s time to focus on language in a situated, interactive setting!

Since that time in mid-August, I’ve been working on a paradigm for simulating situated language acquisition. This post will give a brief overview of the motivating ideas, and I’ll follow up shortly with more concrete details on some experiments I’ve been doing recently.

(Before I get started: this space is rapidly increasing in activity, which is certainly a good thing for science! Facebook Research just released their Environment for Communication-based AI, and there have been murmurs of other similar environments around the Internets.)

The paradigm

One of the key points of “Solving language” was that natural language dialogue is necessarily situated in some grounded context. We use language (and other tools) to accomplish real-world goals, which are themselves often not linguistic. The reference-game example in that post gave one instance of linguistic behavior that was strongly tied to nonlinguistic world knowledge — something we can’t solve as a language problem in isolation.

If we’re interested in building language agents which can eventually cooperate with us via language in similarly grounded contexts, then the learning tasks we design should reflect this goal.

I’ve followed this idea through to design a general paradigm for situated language acquisition. In this paradigm, cooperative agents teach or learn a language in order to accomplish some nonlinguistic goal. Here are the details:

1. A child agent lives in some grounded world and has some goal which is nonlinguistic (e.g. reach a goal region, get food, etc.).
2. The child has only partial observations of its environment, and can take only a subset of the necessary actions to reach its goal.
3. A parent agent also exists in this world. The parent speaks some fixed language and wants to cooperate with the child (to help it reach its goal).
4. The parent has full observations from the environment, and can take actions which the child cannot take on its own.
5. The child and parent can communicate via a language channel.

The environment is designed such that the child cannot accomplish the goal on its own; it must employ the help of its parent. The child acquires language as a side effect of accomplishing its grounded goal: it is the most efficient (or perhaps the only efficient) mechanism for reaching its main goal.

Philosophizing

To clearly restate: a critical and distinguishing factor of this framework is that the child acquires language only as a side effect of striving for some grounded, nonlinguistic goal.

The environment is designed in particular to avoid reifying “language.” I think it is misleading to see language as some sort of unitary thing to be solved — as just one of a few isolated tools in the toolbox of cognition that need to be picked up on the way to general artificial intelligence.

Language is defined by its use. Language-enabled agents are not identified their next-word prediction perplexity or their part-of-speech tag confusion matrix, but by their ability to cooperate with other agents through language. We shouldn’t expect the latter to magically emerge from hill-climbing on any of the former.

As I’ll show in my next post, it’s within our reach to design simple environments that let us directly hill-climb on this objective of cooperation through language. Stay tuned!¹