Event-related potentials reveal the relations between feature representations at different levels of abstraction.

In this paper, we use behavioural methods and event-related potentials (ERPs) to explore the relations between informational and instantiated features, as well as the relation between feature abstraction and rule type. Participants are trained to categorize two species of fictitious animals and then identify perceptually novel exemplars. Critically, two groups are given a perfectly predictive counting rule that, according to Hannah and Brooks (2009.

Influence of familiar features on diagnosis: instantiated features in an applied setting.

Medical diagnosis can be viewed as a categorization task. There are two mechanisms whereby humans make categorical judgments: "analytical reasoning," based on explicit consideration of features and "nonanalytical reasoning," an unconscious holistic process of matching against prior exemplars. However, there is evidence that prior experience can also operate at the level of individual "instantiated" features (Brooks & Hannah, 2006).

Teaching posttraining: influencing diagnostic strategy with instructions at test.

It is believed that medical diagnosis involves two complementary processes, analytic and similarity-based. There is considerable debate as to which of these processes defines diagnostic expertise and how best to teach clinical diagnosis and reduce diagnostic errors. The purpose of these studies is to document the use of these strategies in medical students.

The influence of familiar non-diagnostic information on the diagnostic decisions of novices.

Context: Previous research has demonstrated the influence of familiar symptom descriptions and entire case similarity on diagnostic reasoning. In this paper, we extend the role of familiarity to examine the influence of familiar non-diagnostic patient information (e.g.

Featuring familiarity: how a familiar feature instantiation influences categorization.

We demonstrate that a familiar looking feature can influence categorization through 2 different routes, depending on whether a person is reliant on abstract feature representations or on concrete feature representations. In 2 experiments, trained participants categorized new category members in a 3-step procedure: Participants made an initial categorization, described the rule-consistent features indicated by the experimenter, and then recategorized the item. Critical was what happened on the second categorization after participants initially categorized an item based on a familiar, but misleading, feature.

Teaching from the clinical reasoning literature: combined reasoning strategies help novice diagnosticians overcome misleading information.

Objective: Previous research has revealed a pedagogical benefit of instructing novice diagnosticians to utilise a combined approach to clinical reasoning (familiarity-driven pattern recognition combined with a careful consideration of the presenting features) when diagnosing electrocardiograms (ECGs). This paper reports 2 studies demonstrating that the combined instructions are especially valuable in helping students overcome biasing influences.

Methods: Undergraduate psychology students were trained to diagnose 10 cardiac conditions via ECG presentation.

Diversion of attention in everyday concept learning: identification in the service of use.

Many people tend to believe that natural categories have perfectly predictive defining features. They do not easily accept the family resemblance view that the features characteristic of a category are not individually sufficient to predict the category. However, common category-learning tasks do not produce this simpler-than-it-is belief.

It all make sense: biomedical knowledge, causal connections and memory in the novice diagnostician.

Although there is consensus among medical educators that students must receive training in the biomedical sciences, little is known regarding the role of biomedical knowledge in diagnosis. The present paper presents two studies examining the role of biomedical knowledge, specifically knowledge of causal mechanisms, in novice diagnosticians. In Experiment 1, two groups of participants are taught to diagnose a series of artificial diseases.

The benefits of flexibility: the pedagogical value of instructions to adopt multifaceted diagnostic reasoning strategies.

Objectives: Building on the advice of previous research to avoid parsing diagnostic strategies too finely, recent studies have shown that teaching novices to utilise analytic and non-analytic reasoning strategies yields higher diagnostic accuracy than teaching either in isolation. This study assesses the extent to which students spontaneously adopt a combined approach and compares its benefits with those experienced with a contrastive learning strategy known to enhance analogical transfer.

Methods: A sample of 48 naïve students were trained to identify features on electrocardiograms (ECGs) and assign diagnoses.

The role of biomedical knowledge in diagnosis of difficult clinical cases.

Although biomedical knowledge is believed to be of little value in diagnosis of routine clinical cases, studies of clinical reasoning have found that physicians revert to use of basic biomedical knowledge when faced with challenging clinical problems. The current paper presents two experiments that empirically examine the role of biomedical knowledge in diagnosis of difficult cases by novice diagnosticians. Novices are taught to diagnose a series of artificial diseases using either knowledge of causal mechanisms or a list of clinical features.

Producing biased diagnoses with unambiguous stimuli: The importance of feature instantiations.

In this article, the authors demonstrate a laboratory analogue of medical diagnostic biasing (V. R. LeBlanc, G.

Speed kills? Speed, accuracy, encapsulations and causal understanding.

Background: The role of basic science, which provides causal explanations for clinical phenomena in medical education, is poorly understood. Schmidt has postulated that expert clinicians maintain this knowledge in 'encapsulated' form, indexed by words or phrases describing the processes. In the present paper we show that students who learn causal explanations have a more coherent understanding of the relation between diseases and clinical features which, in turn, influences recognition of words or phrases describing 'encapsulated knowledge' and the ability to maintain performance under speeded conditions.

Instantiated features and the use of "rules.".

Classification "rules" in expert and everyday discourse are usually deficient by formal standards, lacking explicit decision procedures and precise terms. The authors argue that a central function of such weak rules is to focus on perceptual learning rather than to provide definitions. In 5 experiments, transfer following learning of family resemblance categories was influenced more by familiar-appearing features than by novel-appearing features equally acceptable under the rule.

Giving learners the best of both worlds: do clinical teachers need to guard against teaching pattern recognition to novices?

Purpose: There has been much debate in the medical education literature regarding the extent to which feature-driven and nonanalytic (similarity-based) reasoning strategies define expertise, but the relative value of teaching these strategies, together or in isolation, remains uncertain. The purpose of this study was to compare the diagnostic accuracy achieved upon receiving instruction to use each strategy in isolation to that of a combined approach.

Method: In 2003-04, 48 undergraduate psychology students from McMaster University in Ontario, Canada, were taught to diagnose ten cardiac disorders (including normal) via electrocardiogram (ECG) presentation.

The blossoms and the weeds.

As attested by the articles in this issue and the papers given at the festschrift, I have had the privilege of working with a talented group of people. In this article, a critique is given on the bouquet of themes that have bound many of us together, sorting the blossoms from some of the weeds. A brief description is then given of how these themes are working out in our current research on categorization.

The value of basic science in clinical diagnosis: creating coherence among signs and symptoms.

Background: We investigated whether learning basic science mechanisms may have mnemonic value in helping students remember signs and symptoms, in comparison with learning the relation between symptoms and diagnoses directly.

Purpose: To compare 2 approaches to learning diagnosis: learning how features of various conditions relate to underlying pathophysiological mechanisms and learning the conditional probabilities of features and diseases.

Methods: Undergraduate students (n = 36) were taught 4 disorders (upper motor neuron lesion, lower motor neuron lesion, neuromuscular junction disease and muscular disease), either using basic science explanations or (symptom x disease) probabilities.

Using comprehensive feature lists to bias medical diagnosis.

Clinicians routinely report fewer features in a case than they subsequently agree are present. The authors report studies that assess the effect of considering a more comprehensive description than physicians usually offer. These comprehensive descriptions were generated from photographs of dermatology and internal medicine and were complete and accurate.

Limiting the playing field: does restricting the number of possible diagnoses reduce errors due to diagnosis-specific feature identification?

Introduction: Diagnostic hypotheses influence the identification of clinical features by medical trainees. This influence is strong enough to lead students to interpret features incorrectly if the initial diagnostic suggestion is incorrect. In the present study, we investigated whether reducing the pool of possible diagnoses at the time of test to a few highly plausible alternatives would focus the search for and interpretation of clinical features on a few alternative diagnoses and, as a result, reduce the influence of an initial diagnostic hypothesis on feature identification.

The privileged status of prestigious terminology: impact of "medicalese" on clinical judgments.

Purpose: Health professionals frequently use medical terminology like dyspnea or nasopharyngitis. These two studies examine how the use of medical terms affects the judgments of seriousness, prevalence, and disease; and diagnostic judgments.

Method: In study 1, a survey containing the names of 22 diseases with either a medical or lay description was completed by 47 undergraduate psychology students and 25 medical students, who were asked to judge seriousness, prevalence, and how "disease-like" it was.

Practice makes perfect: the critical role of mixed practice in the acquisition of ECG interpretation skills.

Purpose: To examine the effect of instructional format on medical students' learning of ECG diagnosis.

Method: Two experiments employed different learning and practice methods. In the first, students were randomly allocated to one of two instructional approaches, one organized around features (e.

Expert-novice differences in memory: a reformulation.

Background: One of the most discriminating measures of expertise in multiple domains has been performance on memory tasks. In medicine, however, the relation between expertise and memory is more equivocal.

Purpose: To compare and contrast the sufficiency of multiple explanations of this finding by using three probes of memory rather than the traditional free recall task alone.

The Non-Analytical Basis of Clinical Reasoning.

This paper explores the assertion that much of clinical diagnostic thinking is based on the rapid and unconscious matching of the presenting problem to a similar, previously encountered, problem. This 'non-analytic' form of concept formation has been described in the psychology literature for over a decade. From this theory, we deduce and test several hypotheses: 1) Diagnosis is based in part on similarity to a particular previous example.