Investigating Communicative factors and self-oriented functions of Co-speech Gestures

My PhD project will focus on gestures that people spontaneously produce while speaking ("co-speech gestures"). While Psycholinguistics has previously looked at language as a self-contained communication system, recently focus has shifted to investigate how the processing of language is multimodal. Gestures can be used alongside speech when we communicate, and the processes by which speech and gesture are produced and processed are not independent from one another (McNeill, 2000).
I will investigate two functions of gestures that influence how people produce gestures. The first is self-oriented functions of gesture, where gesture is used to facilitate the gesturer's speaking, (Rauscher, Krauss & Chen, 1996) and problem solving, (Chu & Kita, 2008). The second is the communicative function of gestures, where gesture is used to convey information, such as information not conveyed in speech, (Gather, Alibali & Goldin-Meadow, 1998).
It is important to investigate the functions of gestures because they are important for our understanding of communication and cognition. Studies of the communicative function of gesture is important because it broadens our view of "linguistic communication"; they will reveal how people coordinate speech and gesture to convey information across. Studies on the self-oriented functions are important because it contributes to our understanding to what extent our thinking is embodied, that is, how our body movements contribute to thinking (Hostetter & Alibali, 2008).
Strand 1.
The classic finding that supports the idea of communicative functions shaping gesture production is that the speaker produces more gestures when they are face-to-face with the listener than when there is a visual barrier between the speaker and the listener (Alibali, Heath & Myers, 2001). This has been interpreted as evidence that gestures are meant to be seen by the listener. However, this interpretation is questioned in a theoretical paper by Bavelas and Healing, (2013); who argue listener behaviour is not properly controlled for example.
I will investigate the idea that the above visual-barrier effect is a part of a more general mechanism. That is, the more "interactive" conversation is, the more gestures people produce. And, there are various components of interactivity (e.g., visibility of the face, visibility of gesture, dialogue as opposed to monologue) may additively or interactively contribute to the overall interactivity. [...]
Strand 2.
This strand concerns the self-oriented function of gesture. More specifically, I will investigate a key aspect of the Gesture for Conceptualisation hypothesis, (Kita, Alibali & Chu, in press, Psychological Review); namely, gestures can facilitate speech production by activating, manipulating, packaging and exploring spatio-motoric representations to shape them for verbalisation.
Among the four functions, the packaging function has the least empirical support. I will first provide supporting evidence for the packaging function of gesture. Gestures can help people package spatio-motoric information into small units ready to be encoded in a single sentence. This helps people prepare verbalisable information chunks. Indirect evidence for this idea is the finding that difficulty in information packaging (i.e., deciding exactly what information to encode in each sentence) can trigger more gestures. (Hostetter, Alibali & Kita, 2007). However, direct evidence requires manipulation of gestures, which has not been done in the literature.