All past BBS authors, referees and commentators are eligible to become BBS Associates. To help us put together a balanced list of commentators, please give some indication of the aspects of the topic on which you would bring your areas of expertise to bear if you were selected as a commentator. An electronic draft of the full text is available for inspection with a WWW browser, anonymous ftp or gopher according to the instructions that follow after the abstract. Working memory limitations are best defined in terms of the complexity of relations that can be processed in parallel. Relational complexity is related to processing loads in problem solving, and and can distinguish between higher animal species as well as between children of different ages.
Complexity is defined by the number of dimensions, or sources of variation, that are related.
A unary relation has one argument and one source of variation because its argument can be instantiated in only one way at a time. A binary relation has two arguments and two sources of variation because two argument instantiations are possible at once. A ternary relation is three dimensional, a quaternary relation is four dimensional, and so on. Empirical studies of working memory limitations indicate a soft limit which corresponds to processing one quaternary relation in parallel. More complex concepts are processed by segmentation or conceptual chunking.