Does seeing gesture lighten or increase the load?

We examined the cognitive resources involved in processing speech with gesture compared to the same speech without gesture across four studies using a dual-task paradigm. Participants viewed videos of a woman describing spatial arrays either with gesture or without. They then attempted to choose the target array from among four choices. Participants’ cognitive load was measured as they completed this comprehension task by measuring how well they could remember the location and identity of digits in a secondary task. We found that addressees experience additional visuospatial load when processing gestures compared to speech alone, and that the load primarily comes when addressees attempt to use their memory of the descriptions with gesture to choose the target array. However, this cost only occurs when gestures about horizontal spatial relations (i.e., left and right) are produced from the speaker’s egocentric perspective.