I hereby declare that I am the sole author of this thesis. This is a true copy of the thesis, including any required final revisions, as accepted by my examiners. public. I understand that my thesis may be made electronically available to the

), as did all rewards, all tangible rewards, and all expected rewards. Engagement-contingent and completion-contingent rewards also significantly undermined self-reported interest (d =-0.15, and —0.17), as did all tangible rewards and all expected rewards. Positive feedback enhanced both free

Intrinsic and extrinsic types of motivation have been widely studied, and the distinction between them has shed important light on both developmental and educational practices. In this review we revisit the classic definitions of intrinsic and extrinsic motivation in light of contemporary research and theory. Intrinsic motivation remains an important construct, reflecting the natural human propensity to learn and assimilate. However, extrinsic motivation is argued to vary considerably in its relative autonomy and thus can either reflect external control or true self-regulation. The relations of both classes of motives to basic human needs for autonomy, competence and relatedness are discussed. © 2000 Academic Press To be motivated means to be moved to do something. A person who feels no impetus or inspiration to act is thus characterized as unmotivated, whereas someone who is energized or activated toward an end is considered motivated. Most everyone who works or plays with others is, accordingly, concerned with motivation, facing the question of how much motivation those others, or oneself, has for a task, and practitioners of all types face the perennial

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Performance modelling is concerned with the capture and analysis of the dynamic behaviour of computer and communication systems. The size and complexity of many modern systems result in large, complex models. A compositional approach decomposes the system into subsystems that are smaller and more easily modelled. In this thesis a novel compositional approach to performance modelling is presented. This approach is based on a suitably enhanced process algebra, PEPA (Performance Evaluation Process Algebra). The compositional nature of the language provides benefits for model solution as well as model construction. An operational semantics is provided for PEPA and its use to generate an underlying Markov process for any PEPA model is explained and demonstrated. Model simplification and state space aggregation have been proposed as means to tackle the problems of large performance models. These techniques are presented in terms of notions of equivalence between modelling entities. A framewo...

Despite the very extensive literature on dropout from higher education, much remains unknown about the nature of the dropout process. In large measure, the failure of past research to delineate more clearly the multiple characteristics of dropout can be traced to two major shortcomings; namely, inadequate atten-tion given to questions of definition and to the development of theoretical models that seek to explain, not simply to describe, the processes that bring individuals to leave institutions of higher education. With regard to the former, inadequate attention given to definition has often led researchers to lump together, under the rubric of dropout, forms of leaving behavior that are very differ-ent in character. It is not uncommon to find, for instance, research on dropout that fails to distinguish dropout resulting from academic failure from that which is the outcome of voluntary withdrawal. Nor is it uncommon to find permanent dropouts placed together with persons whose leaving may be temporary in I am indebted to my research assistant, John B. Cullen, for having made an extensive literature search and compiling summaries of the literature for me. I am also indebted to Professors Peter Moock, to John Weidman, and to an unknown reviewer for their insightful comments on an earlier draft of this paper. The work reported here overlaps to a large extent work performed for the Office of

This article examines the fundamental

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Our possessions are a major contributor to and reflection of our identities. A variety of evidence is presented supporting this simple and compelling premise. Related streans of research are identified and drawn upon in devetopJng this concept and implications are derived for consumer behavior. Because the construct of exterxJed self involves consumer behavior rather than buyer behavior. It apjpears to be a much richer construct than previous formulations positing a relationship between self-concept and consumer brand choice. Hollow hands clasp ludicrous possessions because they are links in the chain of life If it breaks, they are truly losL—Dichlsr \ 964 W e cannot hope to understand consumer behav-ior without first gaining some understanding of ihe meanings that consumers attach to possessions..• \ key to understanding what possessions mean is rec-ognizing thai, knowingly or unknowingly, intention-ally or unintentionally, we regard our possessions as parts of ourselves. As Tuan argues, "Our fragile sense

A dual taxonomy is presented to reconcile 2 incongruous facts about antisocial behavior: (a) It shows impressive continuity over age, but (b) its prevalence changes dramatically over age, increasing almost 10-fold temporarily during adolescence. This article suggests that delinquency conceals 2 distinct categories of individuals, each with a unique natural history and etiology: A small group engages in antisocial behavior of 1 sort or another at every life stage, whereas a larger group is antisocial only during adolescence. According to the theory of life-course-persistent antisocial behavior, children's neuropsychological problems interact cumulatively with their criminogenic environments across development, culminating in a pathological personality. According to the theory of adolescence-limited antisocial behavior, a contemporary maturity gap encourages teens to mimic antisocial behavior in ways that are normative and adjustive. There are marked individual differences in the stability of antisocial behavior. Many people behave antisocially, but their antisocial behavior is temporary and situational. In contrast, the antisocial behavior of some people is very stable and persistent. Temporary, situational ' antisocial behavior is quite common in the population, especially among adolescents. Persistent, stable antisocial behavior is found among a relatively small number of males whose behavior problems are also quite extreme. The central tenet of this article is that temporary versus persistent antisocial persons constitute two qualitatively distinct types of persons. In particular, I suggest that juvenile delinquency conceals two qualitatively distinct categories of individuals, each in need of its own distinct theoretical explanation. Of course, systems for classifying types of antisocial persons have been introduced before (e. g.,