Bimanual gestures: expressions of spatial representations that accompany speech processes.

The present study investigated a possible relationship between gestures and spatial processes underlying speech, with a focus on both unimanual and bimanual gestures. The amount, form, and type of gestures accompanying spontaneous verbal responses were quantified in five conditions that manipulated the degree to which the verbal description required spatial elaboration. Two conditions that required spatial elaboration included describing one's present house or lounge. To assess gestures accompanying temporally ordered events, a third condition required description of one's daily routine. The two remaining conditions assessed time periods associated with the past (describe the house you lived in as a child) and future (describe the house you would like to live in 15-20 years from now). Higher levels of gesture were found in spatial conditions compared to the temporally ordered routine condition for bimanual gestures, and the reverse was found for unimanual gestures. These results are described in terms of a hypothesised link between bimanual gestures and spatial cognition.