Human and Algorithmic Predictions in Geopolitical Forecasting: Quantifying Uncertainty in Hard-to-Quantify Domains.

Research on clinical versus statistical prediction has demonstrated that algorithms make more accurate predictions than humans in many domains. Geopolitical forecasting is an algorithm-unfriendly domain, with hard-to-quantify data and elusive reference classes that make predictive model-building difficult. Furthermore, the stakes can be high, with missed forecasts leading to mass-casualty consequences. For these reasons, geopolitical forecasting is typically done by humans, even though algorithms play important roles. They are essential as aggregators of crowd wisdom, as frameworks to partition human forecasting variance, and as inputs to hybrid forecasting models. Algorithms are extremely important in this domain. We doubt that humans will relinquish control to algorithms anytime soon-nor do we think they should. However, the accuracy of forecasts will greatly improve if humans are aided by algorithms.

Non-commitment in mental imagery.

We examine non-commitment in the imagination. Across 5 studies (N > 1, 800), we find that most people are non-committal about basic aspects of their mental images, including features that would be readily apparent in real images. While previous work on the imagination has discussed the possibility of non-commitment, this paper is the first, to our knowledge, to examine this systematically and empirically. We find that people do not commit to basic properties of specified mental scenes (Studies 1 and 2), and that people report non-commitment rather than uncertainty or forgetfulness (Study 3). Such non-commitment is present even for people with generally vivid imaginations, and those who report imagining the specified scene very vividly (Studies 4a, 4b). People readily confabulate properties of their mental images when non-commitment is not offered as an explicit option (Study 5). Taken together, these results establish non-commitment as a pervasive component of mental imagery.

Conflicting Goals Influence Physicians' Expressed Beliefs to Patients and Colleagues.

BACKGROUND: Physicians who communicate their prognostic beliefs to patients must balance candor against other competing goals, such as preserving hope, acknowledging the uncertainty of medicine, or motivating patients to follow their treatment regimes. OBJECTIVE: To explore possible differences between the beliefs physicians report as their own and those they express to patients and colleagues. DESIGN: An online panel of 398 specialists in internal medicine who completed their medical degrees and practiced in the United States provided their estimated diagnostic accuracy and prognostic assessments for a randomly assigned case. In addition, they reported the diagnostic and prognostic assessments they would report to patients and colleagues more generally. Physicians answered questions about how and why their own beliefs differed from their expressed beliefs to patients and colleagues in the specific case and more generally in their practice. RESULTS: When discussing beliefs about prognoses to patients and colleagues, most physicians expressed beliefs that differed from their own beliefs. Physicians were more likely to express greater optimism when talking to patients about poor prognoses than good prognoses. Physicians were also more likely to express greater uncertainty to patients when prognoses were poor than when they were good. The most common reasons for the differences between physicians' own beliefs and their expressed beliefs were preserving hope and acknowledging the inherent uncertainty of medicine. CONCLUSION: To balance candor against other communicative goals, physicians tended to express beliefs that were more optimistic and contained greater uncertainty than the beliefs they said were their own, especially in discussions with patients whose prognoses were poor.

Characterization of cross-protection by genetically modified live-attenuated Leishmania donovani parasites against Leishmania mexicana.

Previously, we showed that genetically modified live-attenuated Leishmania donovani parasite cell lines (LdCen(-/-) and Ldp27(-/-)) induce a strong cellular immunity and provide protection against visceral leishmaniasis in mice. In this study, we explored the mechanism of cross-protection against cutaneous lesion-causing Leishmania mexicana. Upon challenge with wild-type L. mexicana, mice immunized either for short or long periods showed significant protection. Immunohistochemical analysis of ears from immunized/challenged mice exhibited significant influx of macrophages, as well as cells expressing MHC class II and inducible NO synthase, suggesting an induction of potent host-protective proinflammatory responses. In contrast, substantial inhibition of IL-10, IL-4, and IL-13 expression and the absence of degranulated mast cells and less influx of eosinophils within the ears of immunized/challenged mice suggested a controlled anti-inflammatory response. L. mexicana Ag-stimulated lymph node cell culture from the immunized/challenged mice revealed induction of IFN-γ secretion by the CD4 and CD8 T cells compared with non-immunized/challenged mice. We also observed suppression of Th2 cytokines in the culture supernatants of immunized/challenged lymph nodes compared with non-immunized/challenged mice. Adoptively transferred total T cells from immunized mice conferred strong protection in recipient mice against L. mexicana infection, suggesting that attenuated L. donovani can provide protection against heterologous L. mexicana parasites by induction of a strong T cell response. Furthermore, bone marrow-derived dendritic cells infected with LdCen(-/-) and Ldp27(-/-) parasites were capable of inducing a strong proinflammatory response leading to the proliferation of Th1 cells. These studies demonstrate the potential of live-attenuated L. donovani parasites as pan-Leishmania species vaccines.