Predecisional information distortion in physicians’ diagnostic judgments: Strengthening a leading hypothesis or weakening its competitor?

© 2014.Decision makers have been found to bias their interpretation of incoming information to support an emerging judgment (predecisional information distortion). This is a robust finding in human judgment, and was recently also established and measured in physicians’ diagnostic judgments (Kostopoulou et al. 2012). The two studies reported here extend this work by addressing the constituent modes of distortion in physicians. Specifically, we studied whether and to what extent physicians distort information to strengthen their leading diagnosis and/or to weaken a competing diagnosis. We used the “stepwise evolution of preference” method with three clinical scenarios, and measured distortion on separate rating scales, one for each of the two competing diagnoses per scenario.In Study 1, distortion in an experimental group was measured against the responses of a separate control group. In Study 2, distortion in a new experimental group was measured against participants’ own, personal responses provided under control conditions, with the two response conditions separated by amonth. The two studies produced consistent results. On average, we found considerable distortion of information to weaken the trailing diagnosis but little distortion to strengthen the leading diagnosis. We also found individual differences in the tendency to engage in either mode of distortion. Given that two recent studies found both modes of distortion in lay preference (Blanchard, Carlson & Meloy, 2014; DeKay, Miller, Schley & Erford, 2014), we suggest that predecisional information distortion is affected by participant and task characteristics. Our findings contribute to the growing research on the different modes of predecisional distortion and their stability to methodological variation

Causal selection – the linguistic take

Causal Selection is a widely discussed topic in philosophy and the cognitive sciences, concerned with characterizing the choice of "the cause" among the many individually necessary and jointly sufficient conditions on which any effect depends on. In this paper, we argue for an additional selection process underlying causal statements: Causative-Construction Selection, which pertains to the choice of linguistic constructions used to express causal relations. By exploring this phenomenon, we aim to answer the following question: given that a speaker wishes to describe the relation between one of the conditions and the effect, which linguistic constructions are available? We take CC-selection to be more crucial than causal selection, since the latter is in fact restricted by the linguistic options resulting from the former. Based on a series of experiments, we demonstrate that factors taken previously as contributing to causal selection should, in fact, be considered as the parameters that license the various linguistic constructions under given circumstances, based on previous knowledge about the causal structure of the world (the causal model). These factors are therefore part of the meaning of the causative expressions

Causal learning through repeated decision making

Abstract Many decisions refer to actions that have a causal impact on other events. Such actions allow for mere learning of expected values, but also for causal learning about the structure of the decision context. Whereas most theories of decision making neglect causal knowledge, causal learning theories emphasize the importance of causal beliefs and assume that people represent decision problems in terms of their causal structure. In three studies we investigated the representations people acquire when repeatedly making decisions to maximize a certain payoff. Our results show that (i) initial causal hypotheses guide the interpretation of decision feedback, (ii) consequences of interventions are used to revise existing causal beliefs, (iii) decision makers use the experienced feedback to induce a causal model of the choice situation, which (iv) enables them to adapt their choices to changes of the decision problem

Predecisional information distortion in physicians’ diagnostic judgments: Strengthening a leading hypothesis or weakening its competitor?

Decision makers have been found to bias their interpretation of incoming information to support an emerging judgment (predecisional information distortion). This is a robust finding in human judgment, and was recently also established and measured in physicians’ diagnostic judgments (Kostopoulou et al. 2012). The two studies reported here extend this work by addressing the constituent modes of distortion in physicians. Specifically, we studied whether and to what extent physicians distort information to strengthen their leading diagnosis and/or to weaken a competing diagnosis. We used the “stepwise evolution of preference” method with three clinical scenarios, and measured distortion on separate rating scales, one for each of the two competing diagnoses per scenario

Electric Motorcycle Using Hub Motor Technology

Due to the current high demand for clean, efficient transportation systems, designers have looked to the electric motor as a means to end the reign of the internal combustion engine (ICE). This has lead to the development of numerous electric vehicles, including motorcycles and scooters, as well as the traditional automobile. The electric drive systems in these vehicles have, for the most part, been retrofitted to mate with existing systems of power transfer commonly found in ICE vehicles. We propose to design a hub motor drive system for motorcycles that eliminates the reuse of these components not necessary in electric motorcycle design. By positioning the motor inside the drive wheel, greater efficiency is achieved, significant parts are eliminated, and space within the frame typically used to house drive components is opened up for battery systems. We plan on utilizing pancake electric motors because of their high torque in narrow configurations. Our motor will be fixed to the swingarm of the bike and will drive an outer housing that will double as the rim of the wheel. We intend to build a functional prototype of the proposed design and fit it to a motorcycle frame for analysis and testing

Multiple paternity in superfetatious live-bearing fishes.

Superfetation, the ability to carry several overlapping broods at different developmental stages, has evolved independently multiple times within the live-bearing fish family Poeciliidae. Even though superfetation is widespread among poeciliids, its evolutionary advantages remain unclear. Theory predicts that superfetation should increase polyandry by increasing the probability that temporally overlapping broods are fertilized by different fathers. Here, we test this key prediction in two poeciliid species that each carry two temporally overlapping broods: Poeciliopsis retropinna and P. turrubarensis. We collected 25 females per species from freshwater streams in South-Eastern Costa Rica and assessed multiple paternity by genotyping all their embryos (420 embryos for P. retropinna; 788 embryos for P. turrubarensis) using existing and newly developed microsatellite markers. We observed a high frequency of unique sires in the simultaneous, temporally overlapping broods in P. retropinna (in 56% of the pregnant females) and P. turrubarensis (79%). We found that the mean number of sires within females was higher than the number of sires within the separate broods (2.92 sires within mothers vs. 2.36 within separate broods in P. retropinna; and 3.40 vs 2.56 in P. turrubarensis). We further observed that there were significant differences in the proportion of offspring sired by each male in 42% of pregnant female P. retropinna and 65% of female P. turrubarensis; however, this significance applied to only 9% and 46% of the individual broods in P. retropinna and P. turrubarensis, respectively, suggesting that the unequal reproductive success of sires (i.e. reproductive skew) mostly originated from differences in paternal contribution between, rather than within broods. Together, these findings tentatively suggest that superfetation may promote polyandry and reproductive skew in live-bearing fishes