Language & Cognition seminar - Prof Sotaro Kita

 

We produce gestures spontaneously not only when we speak ("co-speech gestures"), but also when we think without speaking ("co-thought" gestures). I will first review the evidence that co-speech gestures are highly sensitive to what goes on in speech production. For example, gestural representation of motion events varies as a function of the linguistic structures used to encode motion events.  Gestures are produced more frequently when it is difficult to organise ideas for linguistic expression. Despite these pieces of evidence for a tight link between gesture and language, there are indications that gesture production is dissociable from speech production. Furthermore, new evidence shows that there are important parallelisms between co-speech gestures and co-thought gestures, suggesting that these two types of gestures are produced from the same mechanism. Furthermore, split brain patients' gesturing suggest that speech production and co-speech gesture production are neuroanatomically dissociable. I will conclude that gestures are produced from a mechanism that is inherently independent from, but highly interactive with, the speech production process.