Distributing control appropriately between man and machine is particularly pertinent to assistive technology. We use shared control techniques to augment wheelchair users’ capabilities, enabling them to safely perform precise manoeuvres. In this paper, we investigate the effects of our collaborative controller on the driver, in terms of how their behavioural interaction with the wheelchair changes. We apply a third order analysis to the joystick signals, to gain a better understanding of the user’s interaction with our system. Consequently, we demonstrate how precise manoeuvres, such as driving through doorways, can be achieved with a reduced level of dexterity, requiring fewer corrective joystick movements. However, we note that care should be taken when designing and testing robotic assistive devices, so as not to inadvertently cause deterioration of the user’s capabilities.