You don't act like you trust me: dissociations between behavioural and explicit measures of source credibility judgement.

This study compared explicit and behavioural measures of source credibility judgements based on two factors: a source's past record of accuracy and its production of predictions that participants would like to believe. The former is considered to be a rational factor for judging credibility, while the latter is considered nonrational (i.e., it does not predict actual credibility). In Experiments 1 and 2, participants saw an equal number of predictions from two sources, one of which was either highly or slightly more accurate/desirable than the other. In Experiment 3, either one source was high accuracy and the other high desirability, or one source was higher on both measures. For all experiments, participants then saw new accurate and inaccurate predictions and said which source they thought was most likely to produce each (behavioural task). Participants then gave a percentage rating for each source's perceived accuracy (explicit judgement task). Participants showed sensitivity to past accuracy differences using both tasks, but not to the size of the differences. Desirability influenced performance only on the behavioural task. However, when the two factors conflicted, participants responded solely using past accuracy information. Behaviours reflect source credibility judgements based on both rational and irrational factors, but participants appear to be both more strongly influenced by the rational factor and more aware of that influence.

Self-relevance and wishful thinking: facilitation and distortion in source monitoring.

When making source attributions, people tend to attribute desirable statements to reliable sources and undesirable statements to unreliable sources, a phenomenon known as the wishful thinking effect (Gordon, Franklin, & Beck, 2005). In the present study, we examined the influence of wishful thinking on source monitoring for self-relevant information. On one hand, wishful thinking is expected, because self-relevant desires are presumably strong. However, self-relevance is known to confer a memory advantage and may thus provide protection from desire-based biases. In Experiment 1, source memory for self-relevant information was contrasted against source memory for information relevant to others and for neutral information. Results indicated that self-relevant information was affected by wishful thinking and was remembered more accurately than was other information. Experiment 2 showed that the magnitude of the self-relevant wishful thinking effect did not increase with a delay.

Wishful thinking and source monitoring.

Memory distortions sometimes serve a purpose: It may be in our interest to misremember some details of an event or to forget others altogether. The present work examines whether a similar phenomenon occurs for source attribution. Given that the source of a memory provides information about the accuracy of its content, people may be biased toward source attributions that are consistent with desired accuracy. In Experiment 1, participants read desirable and undesirable predictions made by sources differing in their a priori reliability and showed a wishful thinking bias--that is, a bias to attribute desirable predictions to the reliable source and undesirable predictions to the unreliable source. Experiment 2 showed that this wishful thinking effect depends on retrieval processes. Experiment 3 showed that under some circumstances, wishes concerning one event can produce systematic source memory errors for others.

Diagnostic error in internal medicine.

BACKGROUND: The goal of this study was to determine the relative contribution of system-related and cognitive components to diagnostic error and to develop a comprehensive working taxonomy. METHODS: One hundred cases of diagnostic error involving internists were identified through autopsy discrepancies, quality assurance activities, and voluntary reports. Each case was evaluated to identify system-related and cognitive factors underlying error using record reviews and, if possible, provider interviews. RESULTS: Ninety cases involved injury, including 33 deaths. The underlying contributions to error fell into 3 natural categories: "no fault," system-related, and cognitive. Seven cases reflected no-fault errors alone. In the remaining 93 cases, we identified 548 different system-related or cognitive factors (5.9 per case). System-related factors contributed to the diagnostic error in 65% of the cases and cognitive factors in 74%. The most common system-related factors involved problems with policies and procedures, inefficient processes, teamwork, and communication. The most common cognitive problems involved faulty synthesis. Premature closure, ie, the failure to continue considering reasonable alternatives after an initial diagnosis was reached, was the single most common cause. Other common causes included faulty context generation, misjudging the salience of findings, faulty perception, and errors arising from the use of heuristics. Faulty or inadequate knowledge was uncommon. CONCLUSIONS: Diagnostic error is commonly multifactorial in origin, typically involving both system-related and cognitive factors. The results identify the dominant problems that should be targeted for additional research and early reduction; they also further the development of a comprehensive taxonomy for classifying diagnostic errors.

Cognitive underpinnings of diagnostic error.

Unfortunately, general limits in cognitive performance extend to diagnostic situations. The authors remain optimistic about reducing cognition-based error, but not as optimistic as Croskerry (see his accompanying article), since the reality is that predictable patterns of error will persist.

Reducing diagnostic errors in medicine: what's the goal?

This review considers the feasibility of reducing or eliminating the three major categories of diagnostic errors in medicine: "No-fault errors" occur when the disease is silent, presents atypically, or mimics something more common. These errors will inevitably decline as medical science advances, new syndromes are identified, and diseases can be detected more accurately or at earlier stages. These errors can never be eradicated, unfortunately, because new diseases emerge, tests are never perfect, patients are sometimes noncompliant, and physicians will inevitably, at times, choose the most likely diagnosis over the correct one, illustrating the concept of necessary fallibility and the probabilistic nature of choosing a diagnosis. "System errors" play a role when diagnosis is delayed or missed because of latent imperfections in the health care system. These errors can be reduced by system improvements, but can never be eliminated because these improvements lag behind and degrade over time, and each new fix creates the opportunity for novel errors. Tradeoffs also guarantee system errors will persist, when resources are just shifted. "Cognitive errors" reflect misdiagnosis from faulty data collection or interpretation, flawed reasoning, or incomplete knowledge. The limitations of human processing and the inherent biases in using heuristics guarantee that these errors will persist. Opportunities exist, however, for improving the cognitive aspect of diagnosis by adopting system-level changes (e.g., second opinions, decision-support systems, enhanced access to specialists) and by training designed to improve cognition or cognitive awareness. Diagnostic error can be substantially reduced, but never eradicated.