Negation as structure building in a home sign system

We identify a gestural marker for negation in a home sign system: a side-to-side headshake. This marker expresses a meaning that corresponds semantically to a function that applies to a sentence (whose semantic value is a proposition) and yields another, more complex sentence. Combining negation with a sentence involves sentential modification; we therefore propose that the side-to-side gesture is a structure building operator. We show that it systematically occupies a position at the left periphery of the string, isomorphic to the logical syntax. If what we see in home sign is language creation (Goldin-Meadow 2003), our analysis implies that home signs have at least the minimal syntax of negation, and therefore contributes to ongoing debates about fundamental properties of language