Expert/Novice differences in Diagnostic Medical Cognition - A ...

expertise is associated with the availability of knowledge representations in various forms,
derived from both experience and formal education.
Schmidt & Boshuizen (1993) describe an elaborated model of expertise development in
which the learner is seen as the progressing through a series of consecutive phases, each of which
is characterized by functionally different knowledge structures underlying performance. The first
phase is characterised by the accumulation of causal networks explaining the causes and
consequences of disease in terms of general underlying biological or pathophysiological
processes. Through experience with real cases, this knowledge transforms into narrative
structures called 'illness scripts'. The cognitive mechanisms responsible for this transition are
encapsulation of elaborated knowledge into high level but simplified causal models or even
diagnostic categories, and tuning through the inclusion of contextual information. Illness scripts
thus contain the physician's encapsulated pathophysiological knowledge of the disease and its
consequences, in addition to clinical knowledge of the constraints under which a disease occurs.
When solving a problem, a physician searches for an appropriate script. Once one (or a few) have
been selected, they will tend to match its elements to the information provided by the patient.
Once the script has been instantiated, they remain available in memory as episodic traces of
previously diagnosed patients and are used in the diagnosis of future patients. The third stage is
characterised by the use of these episodic memories of actual patients in the diagnosis of new
cases. They postulated that each type of knowledge forms a layer in memory, and although not
usually applied any more, remains available for use when ontologically more recently acquired
structures fail to produce an adequate representation of a clinical problem.
Rogers (1995) provided insights into the cognitive skills utilised in diagnostic radiology.
She was particularly concerned with describing the interaction between perception and problem
solving. According to the model, radiologists' prior knowledge of both the anatomical region under
consideration and the imaging modality used, allows the expert to retrieve a particular collection
of declarative and procedural knowledge from memory (for example, the anatomical region
implies a certain set of anatomical objects, while the modality calls into play knowledge of the
kinds of perceptual cues likely to be present). This process typically results in the formulation
of a check list allowing the radiologist to conduct a relatively ordered examination. Hence, context
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