On realizable biorders and the biorder dimension of a relation

The paper discusses the mathematical foundations of a technique of multidimensional scaling, generalizing Guttman scaling, in which the structure of the embedding space relies only on ordinal concepts. An empirical relation is represented as an intersection of a minimal number (called bidimension) of Guttman relations. Fairly complete results are given for the cases of bidimensions 1 and 2. In the general case, the main results are based on the equivalence between the bidimension and the dimension of a certain partial order. A characterization of the bidimension as the chromatic number of some hypergraph is also provided.     

On the Representation of Strong and Weak Attitudes About Policy in Memory

A priming paradigm was used to explore the representation of attitudes about government policies in memory. Participants performed pairs of tasks in quick succession. The focal tasks involved evaluating a policy or thinking of one of its consequences. The results showed that thinking of a consequence of a policy speeded up its subsequent evaluation, regardless of whether the participant held a strong or weak attitude about the policy. Evaluating the policy speeded up thinking of one of its consequences for strong attitudes but not for weak ones. In general, it took participants longer to think of a consequence of a policy than to evaluate it. The implications of these results for existing views of the representation of attitudes in memory are discussed.     

Joint Modeling of Ability and Differential Speed Using Responses and Response Times

With computerized testing, it is possible to record both the responses of test takers to test questions (i.e., items) and the amount of time spent by a test taker in responding to each question. Various models have been proposed that take into account both test-taker ability and working speed, with the many models assuming a constant working speed throughout the test. The constant working speed assumption may be inappropriate for various reasons. For example, a test taker may need to adjust the pace due to time mismanagement, or a test taker who started out working too fast may reduce the working speed to improve accuracy. A model is proposed here that allows for variable working speed. An illustration of the model using the Amsterdam Chess Test data is provided.     

Counterfactuals for Consequentialists

That all subjunctive conditionals with true antecedents and trueconsequents are themselves also true is implied by every plausibleand popularly endorsed account. But I am wary of endorsing thisimplication. I argue that all presently endorsed accounts fail tocapture the nature of certain subjunctive conditionals in contextsof consequentialist reasoning. I attempt to show that we must allowfor the possibility that some subjunctive conditionals with trueantecedents and true consequents are false, if we are to believethat certain types of straightforward consequentialist reasoningare coherent. I begin by evaluating a pair of morally releventcounterfactuals in a case via David Lewis's account. I then turnto a slight modification of the case, arguing that Lewis'ssemantics fails to generate the correct truth values of thesubjunctive conditionals in the modified case. Finally, I presenta modified version of Lewis's semantics that generates the correctresults in all of the cases.     

Bayesian estimation of a multilevel IRT model using gibbs sampling

In this article, a two-level regression model is imposed on the ability parameters in an item response theory (IRT) model. The advantage of using latent rather than observed scores as dependent variables of a multilevel model is that it offers the possibility of separating the influence of item difficulty and ability level and modeling response variation and measurement error. Another advantage is that, contrary to observed scores, latent scores are test-independent, which offers the possibility of using results from different tests in one analysis where the parameters of the IRT model and the multilevel model can be concurrently estimated. The two-parameter normal ogive model is used for the IRT measurement model. It will be shown that the parameters of the two-parameter normal ogive model and the multilevel model can be estimated in a Bayesian framework using Gibbs sampling. Examples using simulated and real data are given.     

Asymmetry in the estimation of interpersonal distance and identity affirmation

An asymmetry effect is known to exist in the estimation of interpersonal distance, depending on whether the point of reference for the estimation is the subject (‘How far are the others from you?’) or the others How far are you from the others?). It looks as though, through the effect of a self-centring schema, subjects feel that others occupy their own space more than they occupy the space of others. A self-centring schema has also been found in many other processes involving judgment or comparison of oneself and others. It is generally interpreted as a sign of the affirmation and defence of personal identity. The three experiments reported here attempt to relate the asymmetries in the distances perceived between persons represented on a map to the following three areas in which one's sense of personal or group identity is involved: (1) in the perception of one's own specificity with respect to others (or of the specificity of the group to which one belongs with respect to other groups) (experiment 1), (2) in one's ability to put oneself in the place of others (exocentrism) (experiment 2). and (3) in the individuation of oneself by others (experiment 3). The results of these three experiments lead us to believe that it is indeed the processes of identification and affirmation of personal and group identity - along with the underlying categorization processes — that are the source of the asymmetries observed in interpersonal distance estimation. The consistency of the data obtained in different situations also validates the technique used for estimating interpersonal distance.     

Truth in sentencing

The Canadian Sentencing Commission released its report in 1987. The article draws on the research conducted on behalf of this commission to present a critical overview of the problems of sentencing in Canada. The reform proposed in the commission's report is also discussed. First, the U.S. and the Canadian sentencing systems are contrasted with regard to the issues of determinacy in sentencing, appellate review, and federal jurisdiction. Second, the main problems are identified, namely, disparity, the overuse of incarceration, and the gap between what the sentencing process claims to be doing and its actual operation and effects. Several instances of the divorce between appearance and reality in sentencing are provided and their impact is assessed. Third, the reform proposed by the Canadian Sentencing Commission is outlined and the consequences of adopting a model based on the principle of proportionality are underlined. The article concludes by contrasting two strategies to control the growth of prison populations.     

Some Comments on the Reviews

We comment on the preceding reviews of our book “Memory Evolutive Systems”, discussing the improvements proposed by some of the reviewers and answering to critics of others, in particular on the use of category theory for modeling living systems.