What Sign Language Teaches Us About the Organization of Language

For decades, people believed that language was mostly arbitrary—words and signs with no direct connection to their meaning. But our new research, soon to appear in Proceedings of the National Academy of Sciences (PNAS), shows that this isn’t the full story. We found that iconicity—the resemblance between how a word or sign looks or sounds and what it means—adds an extra layer of structure to language, especially in American Sign Language (ASL).

By studying words and signs in ASL, English, and Spanish, we uncovered a hidden web of relationships linking meaning and form. These connections challenge the long-held belief that language is built only on arbitrary rules. Instead, our findings show that iconicity plays a powerful role in how words and signs are organized, learned, and used.

Why ASL Was Key

ASL helped us see these patterns because its visual nature makes the connections between meaning and form more obvious. For example, the signs for EAT, DRINK, and SNACK all share a meaning (about food or drink) and a form (they are signed near the mouth). The neat thing is that this was extremely common in ASL—nearly half of all ASL signs belong to these kinds of networks. For example, the signs for VANISH, EMPTY, and INVISIBLE share a meaning (about nothingness) and a specific handshape. This shows that ASL’s visual-gestural modality allows signs to directly reflect their meaning in a way that is much harder to spot in spoken languages.

We also found similar patterns in English and Spanish, but they were smaller and less common. For example, in Spanish, iconic word pairs like pam ("bam") and pum ("boom") or tic ("tick") and tac ("tock") create small clusters. In English, we saw words for sharp sounds like bleep, beep, bop, and pop grouped together, along with words for vocal distress like squeal, squeak, and squawk. But compared to ASL, these clusters are far less extensive.

Why This Matters

This research reshapes how we think about language. It shows that iconicity isn’t just a rare feature of certain words or signs—it’s a core principle that works alongside traditional grammar and vocabulary to organize language. In ASL, iconicity helps create networks of signs, making the structure of the language easier to understand.

Even in spoken languages, iconicity plays a role, though it’s subtler. Recognizing these patterns could change how we approach language learning, translation, and even the development of artificial intelligence.

A New Perspective on Language

By including sign languages like ASL in research, we can uncover patterns and principles that would otherwise remain hidden. These findings don’t just help us understand ASL—they transform how we see all human languages.

Language isn’t just a collection of random symbols. It’s a rich, interconnected system where meaning and form shape each other in surprising ways. Recognizing this hidden structure is a game-changer, opening new doors to how we think about communication, learning, and creativity.