"That man's father is my father's son": the roles of structure, strategy, and working memory in solving convoluted verbal problems.

Normative data (N = 896) collected on solutions to the traditional reasoning problem "Brothers and sisters have I none,/That man's father is my father's son" was the platform for a set of experiments to investigate the roles of problem structure, subject strategy, and working memory in error making in a class of verbal problems. The normative data revealed that the modal, but incorrect response to the brothers and sisters problem was "himself," whereas the correct response of "son" was given by only 17% of subjects for the traditional version above, rising to 40% for a reordered novel version. This problem's structure, identified as a double-modifier structure, was found to produce similar response patterns across a range of verbal problems. Results from (1) syntactical structure manipulations (e.g., "My father's son is the father of that man"), and (2) efforts to teach subjects to use a linear strategy (a sequence of steps), interpreted within a framework of Just and Carpenter's (1992) capacity theory of comprehension, suggested that working memory overload varies across within-structure modifications and subjects. Furthermore, this overload may be compounded by subjects' choices of strategy.