Medical expertise asa function of task difficulty

This paper is concerned with factors that disrupt the pattern of forward reasoning characteristic of experts with accurate performance. Two experiments are described. In the first, the performances of cardiologists, psychiatrists, and surgeons in diagnostic explanation of a clinical problem in cardiology were examined. In the second, the performances of cardiologists and endocrinologists in diagnostic explanation of clinical problems within and outside their domains of expertise were examined. The performances of researchers and practicing physicians are also compared. The results of Experiment 1 replicated earlier results regarding the relationship between forward reasoning and accurate diagnosis. There were no differences in recall as a function of expertise. Experts did not show any bias toward using specific knowledge from their own areas of expertise. The results of Experiment 2 showed that the breakdown of forward reasoning was related to the structure of the task. In particular, nonsalient cues induced some backward reasoning even in subjects with accurate diagnoses. Some differences were also found between the types of explanation used by researchers and practitioners. The practitioners referred more to clinical components in their explanations, whereas the researchers focused more on the biomedical components.     

Chronic, severe hypertension does not impair spatial learning and memory in Sprague-Dawley rats

This study tested the hypothesis that long-term hypertension impairs spatial learning and memory in rats. In 6-wk-old Sprague-Dawley rats, chronic hypertension was induced by placing one of three sizes of stainless steel clips around the descending aorta (above the renal artery), resulting in a 20–80-mm Hg increase of arterial pressure in all arteries above the clip, that is, the upper trunk and head. Ten months later, the rats were tested for 5 d in a repeated-acquisition water maze task, and on the fifth day, they were tested in a probe trial; that is, there was no escape platform present. At the end of the testing period, the nonsurgical and sham control groups had similar final escape latencies (16±4 sec and 23±9 sec, respectively) that were not significantly different from those of the three hypertensive groups. Rats with mild hypertension (140–160 mm Hg) had a final escape latency of 25±6 sec, whereas severely hypertensive rats (170–199 mm Hg) had a final escape latency of 21±7 sec and extremely hypertensive rats (>200 Hg) had a final escape latency of 19±5 sec. All five groups also displayed a similar preference for the correct quadrant in the probe trial. Together, these data suggest that sustained, severe hypertension for over 10 mo is not sufficient to impair spatial learning and memory deficits in otherwise normal rats.     

The impact of politeness and relationship on perceived quality of advice about a problem

Advice is a common but potentially problematic way to respond to someone who is distressed. Politeness theory (Brown & Levinson, 1987) suggests advice threatens a hearer's face and predicts that the speaker‐hearer relationship and the use of politeness strategies can mitigate face threat and enhance the effectiveness of advice messages. Students (N=384) read 1 of 16 hypothetical situations that varied in speaker power and closeness of the speaker‐hearer relationship. Students then read 1 of 48 advice messages representing different politeness strategies and rated the message for regard shown for face and for effectiveness. However, neither speaker‐hearer relationship nor politeness strategies was consistently associated with perceived threat to face or perceived advice effectiveness. We suggest revisions to politeness theory and additional factors that may affect judgments of face sensitivity and advice effectiveness.     

Fitts' Law is Applicable to Trunk Coordination Measurements in a Sitting Position

Trunk coordination is essential for many activities of daily living in wheelchair users. This study investigated whether Fitts' law is applicable to trunk movements in a sitting position. Fourteen healthy adults performed two series of 24 tasks of trunk flexion–extension movements in a sitting position. The results showed significant linear relationships between average group movement time (MT) and index of difficulty (ID) over all tasks (r² = 0.92) and within target distances (0.94 < r² < 1.00). Target distance affected intercept and slope (P < 0.001). Hence, Fitts' law is applicable to the studied trunk movements in a sitting position, indicating these trunk movements tasks could serve as a basis for qualitative trunk coordination tests. Transferability of these conclusions to wheelchair users, and optimal test design should be further investigated.     

Subtraction and the solution of open sentence problems

This paper is concerned with the processes used by children in solving open sentence problems of the form x + u = y (Type 1) and u + x = y (Type 2). Three models for reaction times to these problems are proposed. The first assumes they are solved by an incrementing process, the second assumes a decrementing process, while the third assumes that the subject increments or decrements, depending on which is quickest. Two experiments designed to evaluate these models are reported. It is shown, by means of a series of regression analyses that the third model gives the best account of the success latencies to Type 1 problems. This model predicts that times will be a linear function of the minimum of x and y ? x. It is also shown that none of the models give an adequate account of the latency data for Type 2 problems. Some possible reasons for this difference are discussed, together with some evidence that indicates that Type 1 problems and ordinary subtraction problems are solved by the same process.     

Stochastic processes and the guttman simplex

The problem of whether a precise connection exists between stochastic processes of the type considered in mathematical learning theory and the Guttman simplex is investigated. The approach is to consider a class of models that characterize the sequential properties of discrete data, and to derive a set of conditions which a model must satisfy in order to generate inter-trial correlationsr _ij with the ‘perfect simplex’ property:r _ik =r _ij r _jk for all trialsi<j<k. It is shown that the Chapman-Kolomogorov Equations provide a necessary and sufficient condition for this property to hold. It follows that a process which is Markovian in the errors and successes will have this property. It is also shown that, if certain reliability assumptions are introduced, then the all-or-none model has the simplex property if the appropriate correlation coefficients are corrected for attenuation. This research was supported by a grant from the United States Public Health Service, NIMH 07722.