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Biomedical subjects

J F Yates

Publications and source records attributed to J F Yates.

9 recordsLinked to original sources
PubMed2001

Overconfidence effects in category learning: a comparison of connectionist and exemplar memory models.

Exemplar and connectionist models were compared on their ability to predict overconfidence effects in category learning data. In the standard task, participants learned to classify hypothetical patients with particular symptom patterns into disease categories and reported confidence judgments in the form of probabilities. The connectionist model asserts that classifications and confidence are based on the strength of learned associations between symptoms and diseases. The exemplar retrieval model (ERM) proposes that people learn by storing examples and that their judgments are often based on the first example they happen to retrieve. Experiments 1 and 2 established that overconfidence increases when the classification step of the process is bypassed. Experiments 2 and 3 showed that a direct instruction to retrieve many exemplars reduces overconfidence. Only the ERM predicted the major qualitative phenomena exhibited in these experiments.

Adult↗
PubMed1995

Influence of pseudodiagnostic information on the evaluation of ischemic heart disease.

STUDY OBJECTIVES: To measure the influence of classic epidemiologic risk factors (as recorded on the chart) on physicians' admission decisionmaking for patients with suspected acute cardiac ischemia and to compare the influence of those risk factors, which are of limited predictive utility, to the influence of predictively useful information. DESIGN: Retrospective chart review. SETTING: Emergency departments of two community hospitals. PARTICIPANTS: Seven hundred eighty-seven patients evaluated for suspected acute cardiac ischemia, whether admitted or not. RESULTS: Logistic regression revealed that the effect of a recorded history of hypertension on the admission decision (OR, 7.89; 95% CI, 4.57 to 13.58) was greater than that for ST-segment changes on the ECG (OR, 3.98; 95% CI, 2.56 to 6.18) or history of infarction (OR, 2.36; 95% CI, 1.53 to 3.62). A recorded history of diabetes had a small effect (OR, 1.84; 95% CI, 1.01 to 3.36), whereas Q waves and T-wave changes were not statistically significant. CONCLUSION: Physicians' admission decisions appeared to be more heavily influenced by pseudodiagnostic information than by information of objective predictive power. Physicians do not appear to distinguish risk factors from diagnostic information; education may be directed at this distinction.

Acute Disease↗
PubMed1993

Judgmental overshadowing: further evidence of cue interaction in contingency judgment.

We investigated a phenomenon called judgmental overshadowing. Subjects predicted whether each of several patients had a disease on the basis of whether or not the patient had each of two symptoms. For all the subjects, the presence of the disease was moderately contingent on the presence of one of the symptoms (S1). In Condition 1 of our first experiment, the presence of the disease was highly contingent on the presence of the other symptom (S2). In Condition 2, the presence of the disease was independent of S2. Judgmental overshadowing occurred in that the S1-disease contingency was judged to be stronger in Condition 2 than in Condition 1. Subsequent experiments showed that judgmental overshadowing depends little on the form of the judgment, is not due to a response bias or contrast effect, and does not depend on subjects' actively diagnosing each patient. These results are consistent with, and are generally predicted by, an associative-learning model of contingency judgment.

Adult↗
PubMed1990

Seeking and applying diagnostic information in a health care setting.

Many studies have shown that people have difficulty judging the diagnostic value of conditional probability information with respect to one or more hypotheses. The present research addressed two aspects of performing the diagnostic task in a health care decision: (a) recognition of the information's importance, and (b) correct usage of that information. In experiment 1, health care providers, who are trained in, and regularly exposed, to conditional probabilities imparting diagnostic information, exhibited at least a rudimentary recognition of the need for this information in assessing diagnosticity. Experiment 2 indicated that health care and layperson subjects had difficulty in actually applying the information, however. This difficulty prompts a need for judgment aids and caution in using diagnostic information.

Bayes Theorem↗
PubMed1977

Cross-linking of amino acids by formaldehyde. Preparation and 13C NMR spectra of model compounds.

Model cross-linked systems have been prepared by reacting amino acids or alkylamines with formaldehyde and various amino acid model compounds such as 2,4-dimethylphenol (tyrosine), 3-methylindole (tryptophan) and alkylamides (glutamine, asparagine. 13C NMR spectra of the products show the resonances of the formaldehyde-derived methylene carbons in the region 45-60 ppm. Interferences occur from resonances of the alpha-amino acid methine carbons. From the data for these products and other model compounds it has been possible to predict the shifts of the residual methylene carbons in a variety of cross-linked systems. This NMR technique shows promise as a rapid non-degradative method for identification of cross-linking sites.

Amino Acids↗
PubMedDate not supplied

Primacy effects in clinical judgments of contingency.

In contingency judgment a primacy effect exists when a conclusion about the relationship between clinical variables is inordinately influenced by cases seen earlier rather than later in a presentation sequence. In this study, medical and nursing trainees evidenced this behavior in a hypothetical clinical judgment situation. The behavior was tied to an attention decrement explanation, by which inattention to the later-presented cases leads to inaccurate recall of the relative frequencies of observed cases, which in turn induces a misjudgment of a disease-finding contingency. An explicit intervention based on this hypothesis, forcing attention to later cases by warning that recall of the case frequencies would be required, was effective in reducing primacy effects among medical students. A related, but less explicit, intervention was also tried. This intervention did not significantly reduce primacy effects among nursing students, but was somewhat effective among general undergraduate students performing a non-clinical contingency judgment task.

Decision Support Techniques↗
PubMedDate not supplied

Characterizing physicians' perceptions of ambiguity.

Ambiguity, typically characterized as imprecision in judged probabilities is distinguishable from that uncertainty typically measured using probabilities. It reflects the inadequacy of a point probability judgement and the assumptions upon which it is based. Ambiguity influences both patients' and physicians' decisions, but it is unknown how decision makers conceptualize ambiguity. Toward this goal, properties of three ambiguity indicators were examined: a confidence rating, a plausible range, and an interquartile range. Board-certified internists and fourth-year medical students evaluated simulated cases of suspected coronary artery disease. Their judgements provided insights into the three ambiguity indicators. The distribution-based interquartile range was largely redundant with the plausible range, and was least adequate. The confidence rating was not equivalent to the plausible range, and appeared to best reflect the construct of ambiguity as it has been defined.

Computer Simulation↗