In medical problem solving, information learned in the setting of a previous problem is [hopefully] transferred to a new problem [1
]. Medical knowledge is thought to be stored in a network structure and connections between items made on the basis of both pathophysiological and clinical associations [2
]. During the evolution from novice to expert a large amount of new information about diseases is incorporated into the knowledge network and the structure is thought to evolve into an abridged network within which knowledge items are encapsulated into higher order concepts [4
]. The belief that formation of higher order concepts in knowledge structure is an integral step in the pathway to development of expertise has spawned research aimed at both evaluating and facilitating the development of these concepts. In the area of evaluation, for example, analysis of the interrelationship between concepts within a knowledge network (concept mapping analysis, CMA) has been proposed as a tool for evaluating both pre-existing knowledge and knowledge gained as a result of an educational intervention [5
]. An important assumption [and criticism] of CMA is that the map generated represents the 'true' knowledge structure of the subject rather than merely a creation of the research tool; a hypothesis that is difficult to prove. The observation, however, that the map generated by CMA correlates with performance provides some support for this assumption upon which CMA is based [7
In a previous study using concept-sorting as an analysis tool, it was found that medical students who shared more concepts with experts, i.e., with 'expert-type' [or 'deep'] knowledge structure, were more likely to be successful at problem solving than students with 'novice-type' [or 'surface'] knowledge structure [7
]. This initial report was in a single clinical presentation, metabolic alkalosis, but has now also been observed in three other presentations in the clinical presentation of nephrology (metabolic acidosis, hyponatremia and hyperkalemia) [9
]. In the initial report, it was also observed that students who used a conceptual framework, in the form of a diagnostic scheme, to organize learning were more likely to have expert-type knowledge structure [7
]. In the subsequent study, it was observed that when preceptors used diagnostic schemes during the learning experiences, students were more likely to have expert-type knowledge structure [9
]. These studies suggest that the development of expert-type knowledge structure may be facilitated in students by the explicit use of diagnostic schemes during learning and teaching.
A diagnostic scheme is a type of hierarchal conceptual framework where the relationship between the upper and lower levels can be categorized as 'subsumes' [10
]. The diagnostic scheme for metabolic alkalosis is shown in Figure . At the University of Calgary the curriculum is divided into 125 ± 5 clinical presentations and for each presentation a diagnostic scheme is given to students to help organize their learning [11
]. The concepts in the diagnostic schemes and the interrelationship between these concepts were based on the results of CMA of experts in each clinical presentation. While students are encouraged to use and/or modify the diagnostic schemes, the utilization by students during learning is variable. In a previous study, the frequency of diagnostic scheme use by students ranged from 57% to 90% depending upon the clinical presentation [7
]. Seventy two percent of students used the diagnostic scheme for metabolic alkalosis.
Conceptual framework (diagnostic scheme) for the clinical presentation of metabolic alkalosis.
It has previously been shown in education research in children that when students are provided with a conceptual framework, knowledge transfer is enhanced [13
]. In medical education it has also been shown that teaching around pathophysiological concepts, as compared to clinical probability, increases the likelihood of diagnostic success one week after instruction despite there being no initial difference in diagnostic performance, suggesting that providing students with conceptual frameworks to organize learning might aid knowledge retention and transfer [14
]. Another important suggestion from this study is that short-term performance might be a poor predictor of long-term performance and that the relationship between these two may be conditional upon the way in which learning takes place.
The aim of this study was to identify determinants of long-term knowledge structure, as assessed by concept-sorting. The first objective was to examine the change in knowledge structure in medical students over a one year time period, during which time they received no further formal teaching in the clinical presentation under study. The second objective was to examine the association between the use of a conceptual framework (diagnostic scheme) during learning and long-term knowledge structure.