Function allocation: algorithm, alchemy or apostasy?

Fitts gave us our list, the function allocation counterpart of Moses' 10 commandments, or Luther's 95 theses. Based on the qualitative axioms of Fitts, we have sought to evolve function allocation into a science. But can usable algorithms or procedures be attained? Thus far the logic has eluded us, in spite of valiant efforts. Some have declared in disgust that function allocation can never be more than black art, Must we admit that function allocation is mostly art, judgement based on experience, with little prospect for rigorous science? Or in the end must we become apostates, and abandon our hopes for rational function allocation according to those scientific principles we have held so dear in practicing our profession? The paper discusses the following problems of function allocation: (1) computers, automation and robotics offer ever greater capability, but at the cost of greater system complexity and designer bewilderment, making the stakes for function allocation ever higher than before; (2) proper function allocation differs by process stage; (3) automation appears most promising at intermediate complexity, but the bounds of intermediate are undefined; (4) human-centered design, while an appealing slogan, is fraught with inconsistencies in definition and generalizability; (5) naturalistic decision-making and ecological design are incompatible with normative decision theory; (6) function allocation is design, and therefore extends beyond science; and (7) living with the technological imperative, letting our evolving machines show us what they can do, acceding or resisting as the evidence becomes clear, appears inevitable. In spite of our best efforts to cope with these and other problems of function allocation, error and dispute over allocation criteria are human nature. Perhaps that is part of the Darwinian reality, the requisite variety, the progenitor of progress. At least we have it in our power to say no to new technology, or do we? (C) 2000 Academic Press.