No abstract

No abstract

No abstract

Humans are often characterized as Bayesian reasoners. Here, we question the core Bayesian assumption that probabilities reflect degrees of belief. Across 8 studies, we find that people instead reason in a digital manner, assuming that uncertain information is either true or false when using that information to make further inferences. Participants learned about two hypotheses, both consistent with some information but one more plausible than the other. Although people explicitly acknowledged that the less-plausible hypothesis had positive probability, they ignored this hypothesis when using the hypotheses to make predictions. This was true across several ways of manipulating plausibility (simplicity, evidence fit, explicit probabilities) and a diverse array of task variations. Taken together, the evidence suggests that digitization occurs in prediction because it circumvents processing bottlenecks surrounding people's ability to simulate outcomes in hypothetical worlds. These findings have implications for philosophy of science and for the organization of the mind.

Purpose-To determine the radiation dose-effect on the structural integrity of cerebral white matter in craniopharyngioma patients receiving surgery and proton therapy.Methods and Materials-Fifty-one patients (aged 2.1-19.3 years) with craniopharyngioma underwent surgery and proton therapy in a prospective therapeutic trial. Anatomical magnetic resonance images acquired after surgery but before proton therapy were inspected to identify white matter structures intersected by surgical corridors and catheter tracks. Longitudinal diffusion tensor imaging (DTI) was performed to measure microstructural integrity changes in cerebral white matter. Fractional anisotropy (FA) derived from DTI was statistically analyzed for 51 atlasbased white matter structures of the brain to determine radiation dose-effect. FA in surgeryaffected regions in the corpus callosum was compared to that in its intact counterpart to determine whether surgical defects affect radiation dose-effect.Results-Surgical defects were seen most frequently in the corpus callosum because of transcallosal resection of tumors and insertion of ventricular or cyst catheters. The longitudinal DTI data indicated reductions in FA 3 months after therapy, which was followed by a recovery in most white matter structures. A greater FA reduction was correlated with a higher radiation dose in 20 white matter structures, indicating a radiation dose-effect. The average FA in the surgery- Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. HHS Public Access Author Manuscript Author ManuscriptAuthor ManuscriptAuthor Manuscript affected regions before proton therapy was smaller (P =0.0001) than that in their non-surgery affected counterparts with more intensified subsequent reduction of FA (P=0.0083) after therapy, suggesting that surgery accentuated the radiation dose-effect.Conclusions-DTI data suggest that mild radiation dose-effects occur in patients with craniopharyngioma receiving surgery and proton therapy. Surgical defects present at the time of proton therapy appear to accentuate the radiation dose-effect longitudinally. This study supports consideration of pre-existing surgical defects and their locations in proton therapy planning and studies of treatment effect.