book5

Modelling Knowledge-based Creative Design

John S Gero and Mary Lou Maher (Eds.) Lawrence Erlbaum, USA (1993) ISBN 0 8058 11532

"Of that which we cannot speak, of that we must remain silent' was always one of Wittgenstein's most profoundly anti-academic slogans. Whoever got tenure that way'? But at least he had the professional good sense to ignore his own advice. I con- fess that reading this book did occa- sionally lead to twinges of feeling that creativity should be included in Wittgenstein's realm of the un- spoken. But on balance we may perhaps be glad that its contributors joined him in ignoring his advice.

Britain is a culture which shows every sign of simultaneous over-pro- duction and under-application of inventions. Yet during the 60s there was serious attention given by psy- chologists to the problem of how to make the British education system foster creativity and avoid humdrum application of mere intelligence. Heath 's splendidly sceptical opening chapter makes a good case for the necessarily social dimension to the creative act. It was only the second invention of the safety-razor, and the half-century-delayed reinvention of the FAX which were adopted as creative designs. Society has to first invent the problem which breathes creative life into the inventor's solu- tion. Perhaps this is why the use of the word "creative' has been extended to the advertising folk who create the needs which inventions must await'?

In the UK cultural setting, the romantics have much to answer for. The idea of the creative act as an individual cognitive event, with IPR falling to its experiencer, is very much an invention of the 19C ro- mantic movement. Heath 's com- ments about the changing status of science on an inward journey from cultural periphery to cultural core with its attendant increasing load of responsibilities will strike a chord with British scientists struggling to 'realise their potential ' .

With such a healthily sceptical

'preface' behind, the book settles down to ignore its advice and debate whether creativity is an attribute of cognitive process or cognitive pro- duct, and whether anyone has found the model for computat ion which can replace search. I can do no more than take a rather arbitrary sample here.

If we allow ourselves enough defi- nitional rope, pretty much anything can be redefined as search through some transformed space. The most interesting contributions of the book are proposals about how spaces can be created, during design activity, into what theorists, after it's all over, may subsequently re-designate as spaces which were there all the time. Both the Logan & Smithers, and Maher & Zhao chapters make important contributions to the theory of making spaces.

Another recurrent theme is the contrast between generation and recognition. Here it doesn' t matter whether you like the search or the construction metaphor, traveller and builder equally need to be able to recognise the good design if they are not to continue 'forever in uniform motion' . Recognition is often the hardest part for the machine, proba- bly because the very evaluation cri- teria, implicitly imposed by the societal context, are hard for the knowledge engineer. Leaving recog- nition to the user, and designing machines which are good at the drudgework makes a lot of sense.

Fischer's appeal for machines which allow control at the right level of granularity must be right, in general - - we don' t want to word- process at the pixel-level. But many creative designs rely on getting good interactions between analyses at diffbrent levels, and this demands much more than offering control at a single 'right ' level.

Coyne and Subrahmanian argue the proposition that computers will have beneficial effects on human

designers by allowing the search of larger regions of problem space. They quote approvingly Simon's proposal that it is transfer of infor- mation from LTM to WM which is the bottleneck in human information processing. This bottle architecture has to be understood for what it is - a metaphor based on yon Neuman machines applied to the human computer. The problem is that the human computer conducts different sorts of search in different ways, and it's not at all clear that anything liter- ally ~gets transferred" from store to store in any of these searches. Expert chess players exhibit phenomenal search of an enormous problmn space in virtue of what their trained memories return about the relevant local space to search in working memory. A slow (almost pathetic) search using working memory then ensues. It is this last search which Coyne and Subrahmanian want to replace by machine search. They have interesting proposals to make. Eventually, these proposals will have to come up against hard questions about how such a system is to avoid getting in the way of the long-term memory search which is at the root of all human expertise, and which, at present, makes the fastest computer look like a tortoise on Nembutal.

In 'A neuropsychologically based approach to creativity', Takala, inter alia, points out that emotional reac- tions are critical in the creative pro- cess. More specifically it is claimed that the creative process is attended by pleasurable reactions. This led to a retrieval from my LTM of the bio- graphy of Dostoevsky. So pleasur- able did Dostoevsky tind the process of writing novels that he discovered the only way to do it was to run up huge gambling debts, spend his pub- lishers' advance several times over, and wait for the night before the newspaper edition in which his epi- sode was to appear. Only then could he allow himself to enjoy the plea- sures of creation. Fortunately, readers of this book should succeed without such extreme measures.

K Stenning The University of Edinburgh

UK

282 Knowledge-Based Systems Volume 7 Number 4 December 1994