Dual process models of clinical reasoning: The central role of knowledge in diagnostic expertise.

RATIONALE: Research on diagnostic reasoning has been conducted for fifty years or more. There is growing consensus that there are two distinct processes involved in human diagnostic reasoning: System 1, a rapid retrieval of possible diagnostic hypotheses, largely automatic and based to a large part on experiential knowledge, and System 2, a slower, analytical, conscious application of formal knowledge to arrive at a diagnostic conclusion. However, within this broad framework, controversy and disagreement abound. In particular, many authors have suggested that the root cause of diagnostic errors is cognitive biases originating in System 1 and propose that educating learners about the types of cognitive biases and their impact on diagnosis would have a major influence on error reduction. AIMS AND OBJECTIVES: In the present paper, we take issue with these claims. METHOD: We reviewed the literature to examine the extent to which this theoretical model is supported by the evidence. RESULTS: We show that evidence derived from fundamental research in human cognition and studies in clinical medicine challenges the basic assumptions of this theory-that errors arise in System 1 processing as a consequence of cognitive biases, and are corrected by slow, deliberative analytical processing. We claim that, to the contrary, errors derive from both System 1 and System 2 reasoning, that they arise from lack of access to the appropriate knowledge, not from errors of processing, and that the two processes are not essential to the process of diagnostic reasoning. CONCLUSIONS: The two processing modes are better understood as a consequence of the nature of the knowledge retrieved, not as independent processes.

The influence of viewing time on visual diagnostic accuracy: Less is more.

BACKGROUND: Understanding the factors that contribute to diagnostic errors is critical if we are to correct or prevent them. Some scholars influenced by the default interventionist dual-process theory of cognition (dual-process theory) emphasise a narrow focus on individual clinician's faulty reasoning as a significant contributor. In this paper, we examine the validity of claims that dual process theory is a key to error reduction. METHODS: We examined the relationship between a clinical experience (staff and resident physicians) and viewing time on accuracy for categorising chest X-rays (CXRs) and electrocardiograms (ECGs). In two studies, participants categorised images as normal or abnormal, presented at viewing times of 175, 250, 500 and 1000 ms, to encourage System 1 processing. Study 2 extended viewing times to 1, 5, 10 and 20 s to allow time for System 2 processing and a diagnosis. Descriptives and repeated measures analysis of variance were used to analyse the proportion of true and false positive rates (TP and FP) as well as correct diagnoses. RESULTS: In Study 1, physicians were able to detect abnormal CXRs (0.78) and ECGs (0.67) with relatively high accuracy. The effect of experience was found for ECGs only, as staff physicians (0.71, 95% CI = 0.66-0.75) had higher ECG TP than resident physicians (0.63, 95% CI = 0.58-0.68) in Study 1, and staff had lower ECG FP (0.10, 95% CI = 0.03-0.18) than resident physicians (0.27, 95% CI = 0.20-0.33) in Study 2. In other comparisons, experience was equivocal for ECG FPs and CXR TPs and FPs. In Study 2, overall diagnostic accuracy was similar for both ECGs and CXRs, (0.74). There were small interactions between experience and time for TP in ECGs and FP in CXRs, which are discussed further in the discussion and offer insights into the relationship between processing and experience. CONCLUSION: Overall, our findings raise concerns about the practical application of models that link processing type to diagnostic error, or to specific diagnostic error reduction strategies.

Do you hear what you see? Utilizing phonocardiography to enhance proficiency in cardiac auscultation.

INTRODUCTION: Cardiac auscultation skills have proven difficult to train and maintain. The authors investigated whether using phonocardiograms as visual adjuncts to audio cases improved first-year medical students' cardiac auscultation performance. METHODS: The authors randomized 135 first-year medical students using an email referral link in 2018 and 2019 to train using audio-only cases (audio group) or audio with phonocardiogram tracings (combined group). Training included 7 cases with normal and abnormal auscultation findings. The assessment included feature identification and diagnostic accuracy using 14 audio-only cases, 7 presented during training, and 7 alternate versions of the same diagnoses. The assessment-administered immediately after training and repeated 7 days later-prompted participants to identify the key features and diagnoses for 14 audio-only cases. Key feature scores and diagnostic accuracy were compared between groups using repeated measures ANOVA. RESULTS: Mean key feature scores were statistically significantly higher in the combined group (70%, 95% CI 67-75%) compared to the audio group (61%, 95% CI 56-66%) (F(1,116) = 6.144, p = 0.015, ds = 0.45). Similarly, mean diagnostic accuracy in the combined group (68%, 95% CI 62-73%) was significantly higher than the audio group, although with small effect size (59%, 95% CI 54-65%) (F(1,116) = 4.548, p = 0.035, ds = 0.40). Time on task for the assessment and prior auscultation experience did not significantly impact performance on either measure. DISCUSSION: The addition of phonocardiograms to supplement cardiac auscultation training improves diagnostic accuracy and heart sound feature identification amongst novice students compared to training with audio alone.

The effect of prior experience on diagnostic reasoning: exploration of availability bias.

Objectives Diagnostic reasoning has been shown to be influenced by a prior similar patient case. However, it is unclear whether this process influences diagnostic error rates or whether clinicians at all experience levels are equally susceptible. The present study measured the influence of specific prior exposure and experience level on diagnostic accuracy. Methods To create the experience of prior exposure, participants (pre-clerkship medical students, emergency medicine residents, and faculty) first verified diagnoses of clinical vignettes. The influence of prior exposures was measured using equiprobable clinical vignettes; indicating two diagnoses. Participants diagnosed equiprobable cases that were: 1) matched to exposure cases (in one of three conditions: a) similar patient features, similar clinical features; b) dissimilar patient features, similar clinical features; c) similar patient features, dissimilar clinical features), or 2) not matched to any prior case (d) no exposure). A diagnosis consistent with a matched exposure case was scored correct. Cases with no prior exposure had no matched cases, hence validated the equiprobable design. Results Diagnosis A represented 47% of responses in condition d, but there was no influence of specific similarity of patient characteristics for Diagnosis A, F(3,712)=7.28, p=0.28 or Diagnosis B, F(3,712)=4.87, p=0.19. When re-scored based on matching both equiprobable diagnoses, accuracy was high, but favored faculty (n=40) 98%, and residents (n=39) 98% over medical students (n=32) 85%, F(2,712)=35.6, p<0.0001. Accuracy for medical students was 84, 87, 94, and 73% for conditions a-d, respectively, interaction F(2,712)=3.55, p<0.002. Conclusions The differential diagnosis of pre-clerkship medical students improved with prior exposure, but this was unrelated to specific case or patient features. The accuracy of medical residents and staff was not influenced by prior exposure.

It's the destination: diagnostic accuracy and reasoning.

While multiple theories exist to explain the diagnostic process, there are few available assessments that reliably determine diagnostic competence in trainees. Most methods focus on aspects of the process of diagnostic reasoning, such as the relation between case features and diagnostic hypotheses. Inevitably, detailed elucidation of aspects of the process requires substantial time per case and limits the number of cases that can be examined given a limited testing time. Shifting assessment to the outcome of diagnostic reasoning, accuracy of the diagnosis, may serve as a reliable measure of diagnostic competence and would allow increased sampling across cases. The present study is a retrospective analysis of 7 large studies, conducted by 3 research teams, that all used a series of brief written cases to examine the outcome of diagnostic reasoning-the diagnosis. The studies involved over 600 clinicians ranging from final year medical students to practicing emergency physicians. For 4 studies with usable reliability data, reliability for a 2 h test ranged from .63 to .94. On average speeded tests were more reliable (.85 vs. .73).To achieve a reliability of .75 required an average test time of 1.11 h for speeded tests and 1.99 for unspeeded tests. The measure was shown to be positively correlated with both written knowledge tests and measures of problem solving derived from OSCE performance tests. This retrospective analysis provides evidence to support the implementation of outcome-based assessments of clinical reasoning.

Critical thinking, biases and dual processing: The enduring myth of generalisable skills.

CONTEXT: The myth of generalisable thinking skills in medical education is gaining popularity once again. The implications are significant as medical educators decide on how best to use limited resources to prepare trainees for safe medical practice. This myth-busting critical review cautions against the proliferation of curricular interventions based on the acquisition of generalisable skills. STRUCTURE: This paper begins by examining the recent history of general thinking skills, as defined by research in cognitive psychology and medical education. We describe three distinct epochs: (a) the Renaissance, which marked the beginning of cognitive psychology as a discipline in the 1960s and 1970s and was paralleled by educational reforms in medical education focused on problem solving and problem-based learning; (b) the Enlightenment, when an accumulation of evidence in psychology and in medical education cast doubt on the assumption of general reasoning or problem-solving skill and shifted the focus to consideration of the role of knowledge in expert clinical performance; and (c) the Counter-Enlightenment, in the current time, when the notion of general thinking skills has reappeared under different guises, but the fundamental problems related to lack of generality of skills and centrality of knowledge remain. CONCLUSIONS: The myth of general thinking skills persists, despite the lack of evidence. Progress in medical education is more likely to arise from devising strategies to improve the breadth and depth of experiential knowledge.

McMaster at 50: lessons learned from five decades of PBL.

Although educators frequently act as if curricula are as standardized as drug doses (300 mg of PBL t.i.d.), such is not the case. As a case in point, at its inception, Problem Based Learning was hailed as a major curriculum innovation, with the promise of enormous gains in learning outcomes. Very quickly, ecclesiastical debates arose as what was true PBL and what was "modified PBL". Ironically, systematic reviews conducted fairly early in its evolution showed that the gains in learning outcome from PBL were neither large nor uniform (Vernon and Blake in Acad Med 68:550-563, 1993), and the most consistent finding was greater student satisfaction. In this paper, we review five decades of experience with the first PBL curriculum at McMaster. We point out how the curriculum has evolved, both theoretically and practically, in response to external influences, based both on empirical evidence and practical demands. We describe these changes in four broad domains-theoretical rationale, the curriculum, assessment and admissions.

Experienced physician descriptions of intuition in clinical reasoning: a typology.

Background Diagnostic intuition is a rapid, non-analytic, unconscious mode of reasoning. A small body of evidence points to the ubiquity of intuition, and its usefulness in generating diagnostic hypotheses and ascertaining severity of illness. Little is known about how experienced physicians understand this phenomenon, and how they work with it in clinical practice. Methods Descriptions of how experienced physicians perceive their use of diagnostic intuition in clinical practice were elicited through interviews conducted with 30 physicians in emergency, internal and family medicine. Each participant was asked to share stories of diagnostic intuition, including times when intuition was both correct and incorrect. Multiple coders conducted descriptive analysis to analyze the salient aspects of these stories. Results Physicians provided descriptions of what diagnostic intuition is, when it occurs and what type of activity it prompts. From stories of correct intuition, a typology of four different types of intuition was identified: Sick/Not Sick, Something Not Right, Frame-shifting and Abduction. Most physician accounts of diagnostic intuition linked this phenomenon to non-analytic reasoning and emphasized the importance of experience in developing a trustworthy sense of intuition that can be used to effectively engage analytic reasoning to evaluate clinical evidence. Conclusions The participants recounted myriad stories of diagnostic intuition that alerted them to unusual diagnoses, previous diagnostic error or deleterious trajectories. While this qualitative study can offer no conclusions about the representativeness of these stories, it suggests that physicians perceive clinical intuition as beneficial for correcting and advancing diagnoses of both common and rare conditions.