To automate or not to automate: advocating the 'cliff-edge' principle

We reflect briefly on the last forty years or so of ergonomics and human factors research in automation, observing that many of the issues being discussed today are the same as all those decades ago. In this paper, we explicate one of the key arguments regarding the application of automation in complex safety-critical domains, which proposes restraining the capabilities of automation technology until it is able to fully and completely take over the task at hand. We call this the 'cliff-edge' principle of automation design. Instead, we espouse a use for the technology in a more problem-driven, human-centred way. These are not entirely new ideas and such a philosophy is already gaining traction in ergonomics and human factors. The point is that in a given system, tasks should be controlled either by human or by automation; anything in between only causes problems for system performance. Human factors problems with automation have been with us for over forty years, and have changed little in that time. This brief review shows a groundswell of opinion that points to what we call the cliff-edge automation principle - restraining the full capabilities of technology until it is ready to fully and completely take over the task. This approach improves human performance in the system by keeping the person in the loop and in control. Researchers and practitioners in ergonomics and human factors should continue to push this message to the designers and manufacturers of automated systems.