Mr Upjohn’s Debts: Money and Friendship in Early Colonial Calcutta

The paper discusses the effective operation of money and credit among Europeans in Calcutta around 1800, arguing for the importance of informal processes and ties of friendship that facilitated, regulated and enforced agreements, helping both to tide over individuals in times of economic stress and to underwrite the provision and transfer of capital. The argument is advanced by a detailed case study in regard to debts owed by one resident, Aaron Upjohn, to another, Richard Blechynden, amidst a web of acquaintance, officialdom and law that variously ensured that the debts were honoured. It is defined as ‘a support system among acquaintances, necessitated in part by shortage of money and abundance of risk’

Logic and implementation in human reasoning: the psychology of syllogisms

This thesis presents a novel account of syllogistic reasoning, based on data from a non-standard reasoning task called the Individuals Task. An abstract logical treatment of the system, based on a modalised Euler Circles system (Stenning & Oberlander 1994, 1995) is presented, and it is shown that this can be implemented in a diverse range of notationally distinct ways. The Individual Identification Algorithm, as this method is called, makes use of a logical distinction between the premisses of the syllogism; one has an existential, assertive role, and is called the source premiss, whereas the function of the other is to license inference, and so it is called the conditional premiss. This distinction is central to the way the IIA employs modal information to make the use of Euler Circles tractable.The empirical parts of the thesis are concerned with relating the distinction between source and conditional premisses to the Figural Effect (Johnson-Laird & Steedman 1978). It is argued that the Figural Effect is reducible to a tendency for the terms from the source premiss to occur before the terms from the conditional premiss in Individual Conclusions. Since these are comprised of all three terms in the syllogism, it is possible to test new hypotheses concerning the role of the middle term in inference, and the results are shown to be incompatible with all existing theories of the Figural Effect.Since the Individuals Task is non-standard, it is necessary to compare perfor¬ mance profiles on this task with those on the Standard Task; one result of this comparison is that a primary cause of error in the Standard Task is selection of an appropriate quantifier for the conclusion, a result which concurs with the con¬ clusions of Ford (1994) and Wetherick & Gilhooly (1990), but contradicts those of Mental Models theory (Johnson-Laird 1983).Certain anomalies in the prediction of term order by the source/conditional distinction lead to the postulation of a second process for conclusion generation, called Minimal Linking. This logically unsound strategy has effects similar to the illicit conversion of A premisses (Chapman &; Chapman 1959, Revlis 1975)

The simulation of action disorganisation in complex activities of daily living

Action selection in everyday goal-directed tasks of moderate complexity is known to be subject to breakdown following extensive frontal brain injury. A model of action selection in such tasks is presented and used to explore three hypotheses concerning the origins of action disorganisation: that it is a consequence of reduced top-down excitation within a hierarchical action schema network coupled with increased bottom-up triggering of schemas from environmental sources, that it is a more general disturbance of schema activation modelled by excessive noise in the schema network, and that it results from a general disturbance of the triggering of schemas by object representations. Results suggest that the action disorganisation syndrome is best accounted for by a general disturbance to schema activation, while altering the balance between top-down and bottom-up activation provides an account of a related disorder - utilisation behaviour. It is further suggested that ideational apraxia (which may result from lesions to left temporoparietal areas and which has similar behavioural consequences to action disorganisation syndrome on tasks of moderate complexity) is a consequence of a generalised disturbance of the triggering of schemas by object representations. Several predictions regarding differences between action disorganisation syndrome and ideational apraxia that follow from this interpretation are detailed

The Figural Effect and a Graphical Algorithm for Syllogistic Reasoning

Theories of syllogistic reasoning based on Euler Circles have foundered on a combinatorial explosion caused by an inappropriate interpretation of the diagrams. A new interpretation is proposed, allowing single diagrams to abstract over multiple logical models of premises, permitting solution by a simple rule, which involves the identification of individuals whose existence is entailed by the premises. This solution method suggests a performance model. which predicts some of the phenomena of the Figural Effect, a tendency for subjects to prefer conclusions in which the terms preserve their grammatical status from the premises (Johnson-Laird k Steedman 1978). 21 students were asked to identify the necessary individuals for each of the 64 pairs of premis.'5e>. The order in which the three terms specifying the individuals were produced was shown to be as predicted by the performance model. but contrary to the presumed predictions of Mentad Models theory

Comparative Modelling of Learning in a Decision Making Task

In this paper we compare the behaviour of three competing accounts of decision making under uncertainty (a Bayesian account, an associationist account, and a hypothesis testing account) with subject performance in a medical diagnosis task. The task requires that subjects first learn a set of symptom/disease associations. Later, subjects are required to form diagnoses based on limited symptom information. The competing theoretical accounts are embodied in three computational models, each with a single parameter governing the learning rate. Subjects' diagnostic accuracy was used to calibrate the learning rates of the models. The resulting parameter-free models were then used to predict subjects' symptom querying behaviour in a subsequent task. The fit between the Associationist model's predictions and subject behaviour was poor. The fit was slightly better in the case of the Bayesian model, but the hypothesis testing account proved to provide the most adequate account of the data

Quantifier Interpretation and Syllogistic Reasoning: an Individual Differences Account

It is frequently assumed that interpretational errors can explain reasoning errors. However, the evidence for this position has heretofore been less than convincing. Newstead (1995) failed to show expected relations between Gricean implicatures (Grice, 1975) and reasoning errors, and different measures of illicit conversion (Begg & Denny, 1969; Chapman & Chapman, 1959) frequently fail to correlate in the expected fashion (Newstead, 1989; 1990). This paper examines the relation between interpretation and reasoning using the more configurational approach to classifying subjects' interpretation patterns, described in Stenning & Cox (1995). There it is shown that subjects' interpretational errors tend to fall into clusters of properties defined in terms of rashness, hesitancy and the subject/predicate structure of inferences. First we show that interpretations classified by illicit conversion errors, though correlated with fallacious reasoning, are equally correlated with errors which cannot be due to conversion of premises. Then we explore how the alternative method of subject profiling in terms of hesitancy, rashness and subject/predicate affects syllogistic reasoning performance, through analysis in terms of both general reasoning accuracy and the Figural Effect (Johnson-Laird & Bara, 1984). We show that subjects assessed as rash on the interpretation tasks show consistent characteristic error patterns on the syllogistic reasoning task, and that hesitancy, and possibly rashness, interact with the Figural Effect

Implementation of the Combined--Nonlinear Condensation Transformation

We discuss several applications of the recently proposed combined nonlinear-condensation transformation (CNCT) for the evaluation of slowly convergent, nonalternating series. These include certain statistical distributions which are of importance in linguistics, statistical-mechanics theory, and biophysics (statistical analysis of DNA sequences). We also discuss applications of the transformation in experimental mathematics, and we briefly expand on further applications in theoretical physics. Finally, we discuss a related Mathematica program for the computation of Lerch's transcendent.Comment: 23 pages, 1 table, 1 figure (Comput. Phys. Commun., in press

Normative and Information Processing Accounts of Medical Diagnosis

The field of Judgement and Decision Making has for some time been dominated by normative theories which attempt to explain behaviour in mathematical terms. We argue that such approaches provide httle insight into the cognitive processes which govern human decision making. The dominance of normative theories cannot be accounted for by the intractability of processing models. In support of this view, we present a processing account of performance on a simulated medical diagnosis task. The performance of the model, which includes learning, is compared with that of a normative (Bayesian) model, and with subject performance on the task. Although there are some caveats, the processing model is found to provide a more adequate account of subject performance than the Bayesian model

Lyapunov exponents and phase diagrams reveal multi-factorial control over TRAIL-induced apoptosis

Kinetic modeling, phase diagrams analysis, and quantitative single-cell experiments are combined to investigate how multiple factors, including the XIAP:caspase-3 ratio and ligand concentration, regulate receptor-mediated apoptosis