The effects of member expertise on group decision-making and performance

This study assesses the effects of member expertise on group decision-making and group performance. Three-person cooperative groups and three independent individuals solved either an easy or moderately difficult version of the deductive logic game Mastermind. Experimental groups were given veridical performance information, i.e., the members' rankings on prior individual administrations of the task. Control groups were not provided with this information. Results supported the predictions of this study: (1) groups gave more weight to the input of their highest performing members with the group decision-making process being best approximated by post hoc “expert weighted” social decision schemes and (2) groups performed at the level of the best of an equivalent number of individuals.     

Characterizations of Negative Definability in Modal Logic

Negative definability ([18]) is an alternative way of defining classes of Kripke frames via a modal language, one that enables us, for instance, to define the class of irreflexive frames. Besides a list of closure conditions for negatively definable classes, the paper contains two main theorems. First, a characterization is given of negatively definable classes of (rooted) finite transitive Kripke frames and of such classes defined using both traditional (positive) and negative definitions. Second, we characterize the negatively definable classes of rooted general frames.     

非球面人工晶状体临床应用的启示

非球面人工晶状体是波前像差技术与现代白内障手术完美结合的产物,也是多学科联合发展的结果。非球面人工晶状体较传统球面人工晶状体可明显改善白内障患者的视功能。倘若能实现个体化设计,非球面人工晶状体有望取代球面人工晶状体成为人工晶状体的主流。     

Reliability and expected loss: A unifying principle

We provide a unified, theoretical basis on which measures of data reliability may be derived or evaluated, for both quantitative and qualitative data. This approach evaluates reliability as the proportional reduction in loss (PRL) that is attained in a sample by an optimal estimator. The resulting measure is between 0 and 1, linearly related to expected loss, and provides a direct way of contrasting the measured reliability in the sample with the least reliable and most reliable data-generating cases. The PRL measure is a generalization of many of the commonly-used reliability measures.We show how the quantitative measures from generalizability theory can be derived as PRL measures (including Cronbach's alpha and measures proposed by Winer). For categorical data, we develop a new measure for the general case in which each of N judges assigns a subject to one of K categories and show that it is equivalent to a measure proposed by Perreault and Leigh for the case where N is 2.Bruce Cooil is an Associate Professor of Statistics, and Roland T. Rust is a Professor and area head for Marketing. The authors thank three anonymous reviewers and an Associate Editor for their helpful comments and suggestions. This work was supported in part by the Dean's Fund for Faculty Research of the Owen Graduate School of Management, Vanderbilt University.     

Minimization of modal contours: an essential cross-species strategy in disambiguating relative depth

Two chromatically identical patterns, a diamond and a ladder, were shown on a computer touchscreen. Domestic hens were reinforced for pecking at the pattern that was the highest up on a grid that provided pictorial depth information, i.e. on the pattern that to a human appears as being the furthest away. Every tenth trial was a non-rewarded probe trial with the two patterns partially overlapping. In the absence of other cues depth stratification can occur on the basis of a minimization of interpolated occluding contours. In humans the diamond is usually perceived to be in front of the ladder because shorter interpolated contours are needed to account for the occlusive effect of the diamond on the ladder. The hens pecked more often at the ladder during the probe trials. The results suggest that the avian and mammalian visual systems operate along similar principles when dealing with the problem of solving occlusion indeterminacy in chromatically homogeneous patterns. Received: 26 March 1999 / Accepted after revision: 17 September 1999     

Testing equality of correlated proportions with incomplete data on both responses

Two test statistics are proposed for testing the equality of two correlated proportions when some observations are missing on both responses. The performance of these tests in terms of size and power is compared with other tests by means of Monte Carlo simulations. The proposed tests are easily computed and compare favorably with other tests.     

Theory and tests of the conjoint commutativity axiom for additive conjoint measurement

The empirical study of the axioms underlying additive conjoint measurement initially focused mostly on the double cancellation axiom. That axiom was shown to exhibit redundant features that made its statistical evaluation a major challenge. The special case of double cancellation where inequalities are replaced by indifferences–the Thomsen condition–turned out in the full axiomatic context to be equivalent to the double cancellation property but without exhibiting the redundancies of double cancellation. However, it too has some undesirable features when it comes to its empirical evaluation, the chief among them being a certain statistical asymmetry in estimates used to evaluate it, namely two interlocked hypotheses and a single conclusion. Nevertheless, thinking we had no choice, we evaluated the Thomsen condition for both loudness and brightness and, in agreement with other lines of research, we found more support for conjoint additivity than not. However, we commented on the difficulties we had encountered in evaluating it. Thus we sought a more symmetric replacement, which as Gigerenzer and Strube (1983) first noted, is found in the conjoint commutativity axiom proposed by Falmagne (1976, who called it the “commutative rule”). It turns out that, in the presence of the usual structural and other necessary assumptions of additive conjoint measurement, we can show that conjoint commutativity is equivalent to the Thomsen condition, a result that seems to have been overlooked in the literature. We subjected this property to empirical evaluation for both loudness and brightness. In contrast to Gigerenzer and Strube (1983), our data show support for the conjoint commutativity in both domains and thus for conjoint additivity.     

《易经》:人类科学思维和审美思维方式的精典阐释

一本诞生于五千年前的中国古书《易经》,已经包含着深刻的现代科学数理逻辑原理,且与美学的审美逻辑原理互为支持、互为表里,使这两大类本来被认为水火不相容的领域及其独具的思维方式得到了高度完善统一的阐释。从这样的角度来看《易经》,也许会有助于目前心理学界对思维方式及逻辑问题的研究,拓开一条崭新的思路。