Semantic structures, communicative strategies and the emergence of language

My thesis studies communication systems that arise in the absence of linguistic conventions: restricted linguistic systems. Home sign and the language of unsupervised adult second language learners are examples of such systems. Jackendoff (2002) observed that utterances in these systems are governed by semantic principles, such as Agent First (a principle responsible for the intuitive difference between the two simple utterances HIT-TREE-FRED and HIT-FRED-TREE), and argued that they reflect ancient linguistic structures. As such, studying restricted linguistic systems offers a window into the earliest stages of language evolution, as well as offering insights into the cognitive biases which act to shape modern linguistic systems. In my thesis I related restricted linguistic systems to a novel experimental approach, improvised communication. I showed that gesture sequences in the improvised communication experiment are governed by semantic principles which are essentially the same as those governing restricted linguistic systems: we can therefore use improvised communication experiments as a source of evidence for semantic principles in evolutionarily early language. Moreover, I used improvised communication experiments to reveal a new semantic ordering principle governing the expression of intensional meaning. In an improvised communication experiment, participants are asked to describe events using only gesture and no speech. The methodology was first presented by Goldin-Meadow et al. (2008), who showed that participants by-pass the grammar rules of their native language and use a gesture order that is consistent with SOV (i.e. Subject-Object-Verb). Goldin-Meadow et al. conclude that this is the order in which we naturally represent events. In one study I contrasted extensional (e.g., ‘Man kicks ball’) and intensional (e.g., ‘Man searches for ball’) events. These two kinds of events differ semantically (e.g., ‘ball’ is a concrete object when it is an argument of ‘kick’, and an abstract object when it is an argument of ‘search for’), and participants use different orders to communicate about them: they consistently use SOV order for extensional and SVO order for intensional events. In a follow-up study I show that this flexibility in word order has a communicative function: ambiguous SOV gesture sequences are interpreted extensionally, while ambiguous SVO sequences are interpreted intensionally. These findings suggest added subtlety to the Goldin Meadow account: word order in improvised communication is flexible and determined by fine-grained properties of the meaning to be conveyed.