Conceptualisation load triggers gesture production

In the present study we used a picture description task to investigate one contributing factor to gesture rate variation within speakers, namely conceptualisation load. Specifically we investigated whether speakers produce more gestures when the load on conceptualisation processes is higher. We manipulated conceptualisation load, without substantially changing speech formulation, either by modulating the complexity of the to-be-described pictures (Experiment 1) or by introducing a secondary task that uses the same or different resources as the primary description task (Experiment 2). In both studies, we find evidence that speakers produce more gestures at moments of relatively high conceptual load. The results indicate that the linearisation and the focusing components of conceptualisation are tied to gesture production and that increased load on these components results in increased gesture production.