For several years past the cephalotribe has been attracting the attention of obstetricians, as the journals of medicine testify. Much ingenuity has been exerted in profoundly modifying its original construction by A. Baudelocque, nephew of the great accoucheur of the same name, and by other Parisians. These modifications, especially as made by British obstetricians, have appeared to me, on theo...

psychometric measures (cf. Kogan, 1973; McCleUand, 1973). Given this restriction, studies of the functional relation between age and achievement can be roughly grouped into two primary categories. On the one hand, achievement may take the form of noteworthy creativity, in which case the goal is to assess how productivity changes over the life span. Such inquiries focus on individual accomplishm...

Research has found that individuals who are lower in self-control strength because of previous self-control exertions perform more poorly on subsequent tests of self-control. The present studies suggest that this effect may be moderated by motivation. In particular, depletion and motivation jointly determine self-control performance. Individuals who were depleted and believed that the task woul...

David Marr's book Vision attempted to formulate athoroughgoing formal theory of perception. Marr borrowed much of the "computational" level from James Gibson: a proper understanding of the goal of vision, the natural constraints, and the available information are prerequisite to describing the processes and mechanisms by which the goal is achieved. Yet, as a research program leading to a comput...

We develop here a multi-agent model of the creation of knowledge (scientific progress or technological evolution) within a community of researchers devoted to such endeavors. In the proposed model, agents learn in a physical-technological landscape, and weight is attached to both individual search and social influence. We find that the combination of these two forces together with random experi...

Many biologists now recognize that environmental variance can exert important effects on patterns and processes in nature that are independent of average conditions. Jensen's inequality is a mathematical proof that is seldom mentioned in the ecological literature but which provides a powerful tool for predicting some direct effects of environmental variance in biological systems. Qualitative pr...

MicroRNAs (miRNA) are small RNAs that regulate the translation of thousands of message RNAs and play a profound role in mammalian biology. Over the past 5 years, significant advances have been made towards understanding the pathways that generate miRNAs and the mechanisms by which miRNAs exert their regulatory functions. An emerging theme is that miRNAs are both generated by and utilized by lar...

Adults and children have recently been shown to prefer guessing the outcome of a die roll after the die has been rolled (but remained out of sight) rather than before it has been rolled. This result is contrary to the predictions of the competence hypothesis (Heath & Tversky, 1991 ), which proposes that people are sensitive to the degree of their relative ignorance and therefore prefer to guess...

Potential, Prizes and Performance: Testing Tournament Theory with Professional Tennis Data This paper tests two hypotheses from the theory of elimination tournaments: (i) that uneven tournaments, where the contestants are ex ante heterogeneous, entail lower effort exertion; this is a prediction from agency theory that has not been tested empirically before; and (ii) whether incentives set throu...