A model of problem solving: Its operation, validity, and usefulness in thecase of organic-synthesis problems

The Johnstone-El-Banna model of problem solving is based on working-memory theory as well as on Pascual-Leone's M-space theory. The operation and vali dity of the model depends on a number of necessary conditions, such as a si mple logical structure, availability and accessibility of the partial steps , absence of "noise," and lack of familiarity with the problem type. If the se, and some other conditions, are not fulfilled, the model may not operate ; that is, solvers may be successful, even if the information-processing de mand (Z-demand) is greater than their information-processing capacity and, vice versa. Sixteen organic chemical-synthesis problems, with a simple logi cal structure and varying Z-demand from 2 to 8, were used in this work. We studied two samples of students (age 17-18), one without (N = 128) and the other with (N = 191) some previous training (at least in part) in organic-s ynthesis problems. Although the predicted pattern was observed in both samp les, it was found that the model was more useful in the case of the student s without previous training. Finally, the model predicts better with the fi eld-independent and the field-intermediate students, but less so with the f ield-dependent ones. (C) 2000 John Wiley & Sons, Inc.