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This study tested the distinction between knowledge-based choices and gambling decisions. Gambling decisions contain stated probabilities, and success depends on chance only. In knowledge-based decisions, in contrast, the probabilities are usually unknown and the outcomes of a choice depend on a person's ability or knowledge. Three different theoretical accounts were used to predict knowledge-based choices: prospect theory, the competence hypothesis, and probability-focused reasoning. Students (64 women, 93 men, M= 22.4 yr.) chose between a knowledge bet and a sure gain of equal expected value. Analysis showed people prefer a knowledge bet over the sure gain, if the probability of winning is high—in contrast to prospect theory, which predicts the opposite. Both the competence hypothesis and probability focused reasoning can explain these differences, but prospect theory does not. It appears knowledge-based choices and gambling decisions capture different facets of decision-making.

Much research within decision-making has used the standard gambling paradigm where decision outcomes depend only on chance. Many real life decisions, however simply personal control over decision outcomes. This paper addressed the question of how internal controllability influences decision-making. Internal controllability is assumed (i) to enhance unrealistic optimism and (ii) to result in a better cost:benefit ratio. Both tendencies support each other and predict an enhanced attractiveness for internal and controllable choice options. Participants read a scenario and made a decision afterwards. Results supported the prediction: decision-makers take the option they can personally control. This finding widens the narrow perspective inherent in much previous research based on the gambling paradigm.

Pancreas transplantation with systemic venous drainage of the graft causes elevated plasma levels of insulin, known to be a potent regulator of plasma lipoprotein metabolism. We studied 11 post-type I diabetic pancreas-kidney transplant recipients, 9 type I diabetic kidney transplant recipients displaying peripheral hyperinsulinemia due to subcutaneous insulin treatment, 11 nondiabetic kidney transplant recipients as controls for the effects of immunosuppressive medication, and 11 healthy control subjects, all matched for age, sex, and body mass index. We determined fasting lipids, lipoproteins and lipolytic enzymes, as well as postprandial lipid metabolism after a standardized oral fat load. High-density lipoprotein (HDL) cholesterol averaged 1.98 (0.40) mmol/L in pancreas- kidney transplant patients, clearly higher than that of kidney transplant recipients (1.52 (0.36) mmol/L, P<0.05) or of controls (1.50 (0.38) mmol/L, P<0.05). In pancreas-kidney transplant patients postprandial lipemia was lowest and lipoprotein lipase activity was highest (average 32 and 154, respectively, of the mean of the controls) compared with nondiabetic kidney transplant recipients (P<0.005, P<0.05) and healthy controls (P<0.001, P<0.01). In type I diabetic kidney transplant recipients the levels of HDL cholesterol (1.88 (0.63) mmol/L), postprandial lipemia, and lipoprotein lipase activity were intermediate between pancreas-kidney transplant patients and healthy controls. The distinctly elevated HDL cholesterol in pancreas-kidney transplant patients can be readily explained by the low postprandial triglyceride levels resulting from a high activity of lipoprotein lipase. The very favorable lipid profile in post-diabetic pancreas-kidney transplant recipients could be expected to counteract the severe atherosclerotic risk of long-standing diabetes.