Metaphor as categorisation: a connectionist implementation

A key issue for models of metaphor comprehension is to explain how in some metaphorical comparison , only some features of B are transferred to A. The features of B that are transferred to A depend both on A and on B. This is the central thrust of Black's well known interaction theory of metaphor comprehension (1979). However, this theory is somewhat abstract, and it is not obvious how it may be implemented in terms of mental representations and processes. In this paper we describe a simple computational model of on-line metaphor comprehension which combines Black's interaction theory with the idea that metaphor comprehension is a type of categorisation process (Glucksberg & Keysar, 1990, 1993). The model is based on a distributed connectionist network depicting semantic memory (McClelland & Rumelhart, 1986). The network learns feature-based information about various concepts. A metaphor is comprehended by applying a representation of the first term A to the network storing knowledge of the second term B, in an attempt to categorise it as an exemplar of B. The output of this network is a representation of A transformed by the knowledge of B. We explain how this process embodies an interaction of knowledge between the two terms of the metaphor, how it accords with the contemporary theory of metaphor stating that comprehension for literal and metaphorical comparisons is carried out by identical mechanisms (Gibbs, 1994), and how it accounts for both existing empirical evidence (Glucksberg, McGlone, & Manfredi, 1997) and generates new predictions. In this model, the distinction between literal and metaphorical language is one of degree, not of kind

AIDS and income distribution in Africa. A micro-simulation study for Cˆote d’Ivoire

We develop a demo-economic micro-simulation model able to simulate over a fifteen years period the impact of AIDS on household and individual incomes. When focusing on the labor supply effects of over- mortality, the main effect of AIDS in Cˆote d’Ivoire is a shrinking of the size of the economy by around 6% after 15 years, leaving average income per capita, income inequality, and poverty roughly unchanged. The dependency ratio is not much modified by the epidemic. These conclusions do not seem to depend on the degree of heterogeneity and clustering of the HIV/AIDS-infections over the population.AIDS, labor supply, income distribution

The Measurement of Income Distribution Dynamics when Demographics are correlated with Income

The purpose of our paper is to derive instructive analytics on how to account for differentials in demographic variables, in particular mortality, when performing welfare comparisons over time. The idea is to apply various ways of `correcting' estimated income distribution measures for `sample selection' due to differential mortality. We implement our approach empirically using three waves of the Indonesian Family Life Surveys (IFLS). We distinguish the direct effect of mortality, i.e. individuals who die leave the population and no longer contribute to monetary welfare, from the indirect effect, i.e. the impact on survivors in the deceased's household who may experience a decrease or increase in monetary welfare. In the case of Indonesia, we show that the direct and indirect effects of mortality on income distribution have opposite signs, but are roughly the same in magnitude. We also show that the effects of other demographic changes- such as changes in the structure of fertility, migration and educational attainment- dominate the effects of mortality, whether direct or indirect. However, we find that none of these demographic developments is substantial enough to explain a significant part of the change in income distribution, regardless of whether the pre-crisis period (1993- 1997) or the post-crisis period (1997-2000) is considered.Differential Mortality, Income Distribution Dynamics, Welfare Comparisons, Decomposition.

Socio-economic status, sexual behavior, and differential AIDS mortality Evidence from Cˆote d’Ivoire

Lack of knowledge about differential AIDS mortality seriously hampers the study of the economic impact of AIDS in developing countries, at both the macro and micro-economic levels. In this paper, we derive, we think, reasonable assumptions on mortality differentials by age, education, and other micro-economic characteristics by exploiting variables from the Ivorian Demographic and Health Survey. Finally these differentials are calibrated on UN demographic projections to obtain disaggregated mortality tables. Our model is based on econometrically estimated equations using commonly available individual characteristics, therefore it can be used to forecast mortality differentials for other surveys as well. A main result of our model is that educated people have a higher risk of dying of AIDS, because they are more likely to have several sexual partners. This effect is however partly offset by a higher probability of condom use relative to less educated people. The identification of the socio-economic characteristics of low and high risk groups seems indispensable to set up adequate AIDS prevention and therapy policies in developing countries.AIDS, Demographic and Health Survey, differential mortality, sexual behavior