Everyday body coordinations such as standing or walking appear to require little conscious effort, but research is showing that a variety of cognitive tasks and postural control can mutually interfere, especially in older people. Cognitive load has also been identified as a factor in falling in old age. The present research aims to bridge practical concern over fall-prevention and avoidant non-mobility in old age, and theoretical interest in the source of these dual-task interactions. It studies the effects of imagining one's own manual actions (such as reaching movements) on the control of upright stance. Imagined movements have timing and effort characteristics very similar to real ones, and the planning of them is expected to interact with the current postural state and vulnerabilities of the body. Through experiments in which healthy young and older adults perform physical and imagined reaching movements at various orientations relative to the body, and under different levels of physical load, this project seeks to identify the extent to which dual-task interference is spatially selective (ie, aggravated when imagined actions align with directions of postural vulnerability).