On the impossibility of predicting the behavior of rational agents.
A foundational assumption in economics is that people are rational: they choose optimal plans of action given their predictions about future states of the world. In games of strategy this means that each player's strategy should be optimal given his or her prediction of the opponents' strategies. We demonstrate that there is an inherent tension between rationality and prediction when players are uncertain about their opponents' payoff functions. Specifically, there are games in which it is impossible for perfectly rational players to learn to predict the future behavior of their opponents (even approximately) no matter what learning rule they use. The reason is that in trying to predict the next-period behavior of an opponent, a rational player must take an action this period that the opponent can observe. This observation may cause the opponent to alter his next-period behavior, thus invalidating the first player's prediction. The resulting feedback loop has the property that, a positive fraction of the time, the predicted probability of some action next period differs substantially from the actual probability with which the action is going to occur. We conclude that there are strategic situations in which it is impossible in principle for perfectly rational agents to learn to predict the future behavior of other perfectly rational agents based solely on their observed actions. (+info)
International Study on Syncope of Uncertain Etiology 2: the management of patients with suspected or certain neurally mediated syncope after the initial evaluation rationale and study design.
STUDY DESIGN: Multi-centre, prospective observational study. OBJECTIVES: Main objective is to verify the value of implantable loop recorder (ILR) in assessing the mechanism of syncope and the efficacy of the ILR-guided therapy after syncope recurrence. INCLUSION CRITERIA: Patients who met the following criteria are included: suspected or definite neurally mediated syncope based on initial evaluation; >/=3 syncope episodes in the last 2 years; severe clinical presentation of syncope requiring treatment initiation in the judgement of the investigator and age >30 years. EXCLUSION CRITERIA: Patients with one or more of the following are excluded: carotid sinus syndrome; suspected or definite heart disease and high likelihood of cardiac syncope; symptomatic orthostatic hypotension diagnosed by standing blood pressure measurement; loss of consciousness different from syncope (e.g. epilepsy, psychiatric, metabolic, drop-attack, TIA, intoxication, cataplexy) and subclavian steal syndrome. END-POINTS: The primary end-points are the ECG-documented syncopal events and the syncope recurrences after application of ILR-guided therapy. SAMPLE SIZE AND DURATION: A minimum of 400 patients will be enrolled during an anticipated period of 3 years. (+info)
Prevalence rate and reasons for refusals of influenza vaccine in elderly.
More knowledge on the reasons for refusal of the influenza vaccine in elderly patients is essential to target groups for additional information, and hence improve coverage rate. The objective of the present study was to describe precisely the true motives for refusal. All patients aged over 64 who attended the Medical Outpatient Clinic, University of Lausanne, or their private practitioner's office during the 1999 and 2000 vaccination periods were included. Each patient was informed on influenza and its complications, as well as on the need for vaccination, its efficacy and adverse events. The vaccination was then proposed. In case of refusal, the reasons were investigated with an open question. Out of 1398 patients, 148 (12%) refused the vaccination. The main reasons for refusal were the perception of being in good health (16%), of not being susceptible to influenza (15%), of not having had the influenza vaccine in the past (15%), of having had a bad experience either personally or a relative (15%), and the uselessness of the vaccine (10%). Seventeen percent gave miscellaneous reasons and 12% no reason at all for refusal. Little epidemiological knowledge and resistance to change appear to be the major obstacles for wide acceptance of the vaccine by the elderly. (+info)
Preventing errors in clinical practice: a call for self-awareness.
While ascribing medical errors primarily to systems factors can free clinicians from individual blame, there are elements of medical errors that can and should be attributed to individual factors. These factors are related less commonly to lack of knowledge and skill than to the inability to apply the clinician's abilities to situations under certain circumstances. In concert with efforts to improve health care systems, refining physicians' emotional and cognitive capacities might also prevent many errors. In general, physicians have the sensation of making a mistake because of the interference of emotional elements. We propose a so-called rational-emotive model that emphasizes 2 factors in error causation: (1) difficulty in reframing the first hypothesis that goes to the physician's mind in an automatic way, and (2) premature closure of the clinical act to avoid confronting inconsistencies, low-level decision rules, and emotions. We propose a teaching strategy based on developing the physician's insight and self-awareness to detect the inappropriate use of low-level decision rules, as well as detecting the factors that limit a physician's capacity to tolerate the tension of uncertainty and ambiguity. Emotional self-awareness and self-regulation of attention can be consciously cultivated as habits to help physicians function better in clinical situations. (+info)
Physicians' evaluations of patients' decisions to refuse oncological treatment.
OBJECTIVE: To gain insight into the standards of rationality that physicians use when evaluating patients' treatment refusals. DESIGN OF THE STUDY: Qualitative design with in depth interviews. PARTICIPANTS: The study sample included 30 patients with cancer and 16 physicians (oncologists and general practitioners). All patients had refused a recommended oncological treatment. RESULTS: Patients base their treatment refusals mainly on personal values and/or experience. Physicians mainly emphasise the medical perspective when evaluating patients' treatment refusals. From a medical perspective, a patient's treatment refusal based on personal values and experience is generally evaluated as irrational and difficult to accept, especially when it concerns a curative treatment. Physicians have a different attitude towards non-curative treatments and have less difficulty accepting a patient's refusal of these treatments. Thus, an important factor in the physician's evaluation of a treatment refusal is whether the treatment refused is curative or non-curative. CONCLUSION: Physicians mainly use goal oriented and patients mainly value oriented rationality, but in the case of non-curative treatment refusal, physicians give more emphasis to value oriented rationality. A consensus between the value oriented approaches of patient and physician may then emerge, leading to the patient's decision being understood and accepted by the physician. The physician's acceptance is crucial to his or her attitude towards the patient. It contributes to the patient's feeling free to decide, and being understood and respected, and thus to a better physician-patient relationship. (+info)
In what sense are addicts irrational?
Rationality is here considered from a functional viewpoint: How may the concept of rationality be best used in talking about addictive behavior? The article considers rationality in terms of overt behavioral patterns rather than as a smoothly operating logic mechanism in the head. The economic notion of rationality as consistency in choice - the property of exponential time discount functions - is examined and rejected. Addicts are not irrational because of the type of time discount function that governs their choices-or even because of the steepness of that function. Instead, rationality is here conceived as a pattern of predicting your own future behavior and acting upon those predictions to maximize reinforcement in the long run. Addicts are irrational to the extent that they fail to make such predictions and to take such actions. (+info)
The behavioral economics of will in recovery from addiction.
Behavioral economic studies demonstrate that rewards are discounted proportionally with their delay (hyperbolic discounting). Hyperbolic discounting implies temporary preference for smaller rewards when they are imminent, and this concept has been widely considered by researchers interested in the causes of addictive behavior. Far less consideration has been given to the fact that systematic preference reversal also predicts various self-control phenomena, which may also be analyzed from a behavioral economic perspective. Here we summarize self-control phenomena predicted by hyperbolic discounting, particularly with application to the field of addiction. Of greatest interest is the phenomenon of choice bundling, an increase in motivation to wait for delayed rewards that can be expected to result from making choices in whole categories. Specifically, when a person's expectations about her own future behavior are conditional upon her current behavior, the value of these expectations is added to the contingencies for the current behavior, resulting in reduced impulsivity. Hyperbolic discounting provides a bottom-up basis for the intuitive learning of choice bundling, the properties of which match common descriptions of willpower. We suggest that the bundling effect can also be discerned in the advice of 12-step programs. (+info)
An updated version of the Weigl discriminates adults with dementia from those with mild impairment and healthy controls.
Dementia screening batteries often fall short on measures of executive functioning. The Weigl Color Form Sorting Test (WCFST) is a candidate for inclusion in such batteries, but can be insensitive to mild disturbance. The WCFST consists of 12 colored geometric shapes and requires the patient to sort the pieces by color or form, and then shift to the other sorting principle unassisted. We created a modified version of the WCFST (the Weigl-R) with increased conceptual complexity by adding two stimulus dimensions (texture and central shapes). The range of scores was also increased by adding the extent of examiner assistance required to achieve a correct sort, ability to verbalize conceptual strategy, and number of perseverations. We administered the Weigl-R to a group of 30 patients with mixed dementias, 34 adults with cognitive impairment without dementia, and 21 healthy controls. The new measure discriminated well between healthy controls and older adults with either cognitive impairment without dementia, or dementia. The Weigl-R may be a useful adjunct to brief dementia batteries but requires further validation. (+info)