Lifespan development of stimulus-response conflict cost: similarities and differences between maturation and senescence

Age gradient of the mechanism of stimulus-response conflict cost was investigated in a population-based representative sample of 291 individuals, covering the age range from 6 to 89 years. Stimulus-response conflict cost, indicated by the amount of additional processing time required when there is a conflict between stimulus and response options, follows a U-shaped function across the lifespan. Lifespan age gradient of conflict cost parallels closely those of processing fluctuation and fluid intelligence. Individuals at both ends of the lifespan displayed a greater amount of processing fluctuation and at the same time a larger amount of conflict cost and a lower level of fluid intelligence. After controlling for chronological age and baseline processing speed, conflict cost continues to correlate significantly with fluid intelligence in adulthood and old age and with processing fluctuation in old age. The relation between processing fluctuation and conflict cost in old age lends further support for the neuromodulation of neuronal noise theory of cognitive aging as well as for theories of dopaminergic modulation of conflict monitoring

Unlimited Liability as a Barrier to Entry.

Many, but not all, firms have the freedom to choose liability rules. In some countries, service professions have unlimited liability rules imposed by government; historically, banks in some countries faced unlimited liability. Why do governments impose unlimited liability? This is the question the authors address. With a simple model, they illustrate the agency conflicts in firms. Limited liability solves these conflicts efficiently. Unlimited liability raises the cost of capital; inefficiently small firms result. But under some conditions, selectively-applied unlimited liability rules protect rents. The authors test several propositions with data on Scottish banking and U.S. law firms. Copyright 1988 by University of Chicago Press.

Buyer Groups

When does it pay a coalition of buyers and a coalition of sellers to by-pass a noncooperative market outcome by negotiating an alternative contract? Should these collective contracts be allowed? This paper investigates one source of the incentive for collective contracting: the failure of monopolistically competitive markets to achieve the optimal trade-off between lower costs and greater variety or availability of products. A collective contract benefits buyers inside the coalition but imposes a negative externality on buyers outside the coalition, who face higher prices and lower availability when the contract is allowed. We analyze the conditions under which the collective contracts increase total welfare. We suggest that the model represents one component of the incentives for "managed competition" in health care markets.buyer groups, monopolistic competition, managed care, preferred provider organizations