Performance of layout algorithms: Comprehension, not computation

Many algorithms address the problem of rendering an abstract graph structur e as a diagram in as efficient and as elegant a manner as possible. The cri teria for judging the worth of these algorithms are typically the extent to which they conform to common aesthetic criteria (e.g. minimising the numbe r of crossings, maximising symmetry), or their computational efficiency. Th e algorithms are not usually judged on their ability to produce diagrams th at maximise humans' performance on tasks which require their use. This paper presents an example experimental methodology for considering the relative worth of eight layout algorithms with respect to human performanc e, together with details of an experiment using a single graph. The results indicate that, with the exception of one algorithm, there is no statistica l difference between the performance data of the algorithms when applied to this graph, indicating that they produce drawings of comparable difficulty . This result is despite the different aesthetic bases for the algorithms. (C) 1998 Academic Press.