DOCSLIB.ORG

Multidimensional Perceptual-Cognitive Skills Training Reduces Spatio-Temporal Errors and Improves Dynamic Performance Among Seniors

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Multidimensional Perceptual-Cognitive Skills Training Reduces Spatio-Temporal Errors and Improves Dynamic Performance Among Seniors MULTIDIMENSIONAL PERCEPTUAL-COGNITIVE SKILLS TRAINING REDUCES SPATIO-TEMPORAL ERRORS AND IMPROVES DYNAMIC PERFORMANCE AMONG SENIORS By RYAN J. CASERTA A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2007 © 2007 Ryan J. Caserta This dissertation is dedicated to my mother and father. Thank you for making this dream come true. ACKNOWLEDGMENTS First, I thank my advisor, Dr. Christopher M. Janelle, for seeing me through the last leg of my journey. No words can express the respect I have for him as a professional and, more importantly, as a person. I also thank Dr. Robert N. Singer for his academic and life wisdom of which both have served me well throughout my time at the University of Florida. His friendship will stay with me forever. Special thanks goes to my doctoral committee, Dr. Heather Hausenblas, Dr. John Chow, and Dr. Ira Fischler, for their expertise, insight, and hard work. Finally, I thank my parents, Jean and Ron Caserta. Through their sacrifice and support, I was able to receive this Ph.D. However, they have given me the greatest gift of all – love. iv TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................................................................................. iv LIST OF TABLES............................................................................................................ vii LIST OF FIGURES ......................................................................................................... viii ABSTRACT....................................................................................................................... ix CHAPTER 1 INTRODUCTION ........................................................................................................1 Perceptual-Cognitive Skills Training in Military and Sport.........................................3 Situation Awareness ..............................................................................................4 Anticipation and Pre-Performance Cues ...............................................................7 Multidimensional Approach..................................................................................9 Acquisition and Retention of Perceptual-Cognitive Skills in Older Athletes ............10 Cognitive Function ..............................................................................................11 Cognitive Performance........................................................................................12 Summary and Hypotheses ..........................................................................................13 2 REVIEW OF LITERATURE.....................................................................................16 Theories of Perception and Action .............................................................................16 Information-Processing Approach.......................................................................17 Theory of the Perceptual Cycle ...........................................................................21 From Past to Present: Training Perceptual-Cognitive Skills ......................................24 The 1950s and 1960s...........................................................................................24 The 1980s and the Early 1990s ...........................................................................27 The Late 1990s to the Present .............................................................................35 Conclusions and Future Directions.............................................................................55 3 METHOD ...................................................................................................................59 Participants .................................................................................................................59 Materials and Measures ..............................................................................................59 Video Camcorder.................................................................................................59 Mini-Mental State Examination (MMSE)...........................................................60 v Situation Awareness Global Assessment Technique (SAGAT) .........................60 Posttest Questionnaire .........................................................................................63 Tennis Log...........................................................................................................63 Procedure ....................................................................................................................64 Prescreening ........................................................................................................64 Pretest ..................................................................................................................65 Experimental Treatment ......................................................................................65 Multidimensional Perceptual-Cognitive Skills Training (MPCT) ......................66 Traditional Anticipation-Only Training (AT) .....................................................69 Technique-Footwork Training (TFT)..................................................................70 Control.................................................................................................................72 Posttest.................................................................................................................72 Retention Test......................................................................................................72 Data Reduction ...........................................................................................................72 Response Speed...................................................................................................74 Response Accuracy .............................................................................................74 Performance Decision-Making............................................................................75 Statistical Analysis......................................................................................................75 Cognitive Functioning Analyses .........................................................................75 Performance Analyses.........................................................................................76 4 RESULTS...................................................................................................................78 Cognitive Functioning ................................................................................................78 Performance................................................................................................................79 5 DISCUSSION.............................................................................................................90 Perceptual-Cognitive Training and Performance Outcomes ......................................91 Effects on Cognitive Aging ........................................................................................95 Summary and Future Directions.................................................................................96 APPENDIX A MINI-MENTAL STATE EXAMINATION ............................................................101 B POSTTEST QUESTIONNAIRE..............................................................................103 C TENNIS LOG...........................................................................................................105 D SITUATION AWARENESS GLOBAL ASSESSMENT TECHNIQUE................106 LIST OF REFERENCES.................................................................................................108 BIOGRAPHICAL SKETCH ...........................................................................................116 vi LIST OF TABLES Table page 1-1 Response Speed Findings...........................................................................................8 3-1 Format of Goal-Directed Task Analysis ..................................................................61 3-2 Goal-Directed Task Analysis for Singles Tennis Matches ......................................61 3-3 Final Participant Characteristics According to Group .............................................64 4-1 Pretest, Posttest, and Retention Test Mean Scores and Standard Deviations for Scores on the MMSE as a Function of Cognitive Impairment ................................80 4-2 Pretest, Posttest, Retention Test, and Total Mean Scores and Standard Deviations for the Speed of Play (ms) as a Function of Training ............................81 4-3 Mean Scores and Standard Deviations for the Amount of Independent Practice as a Function of Training .........................................................................................82 4-4 Pretest, Posttest, and Retention Test Mean Scores and Standard Deviation for Measures of Perceptual-Cognitive Ability as a Function of Training .....................85 vii LIST OF FIGURES Figure page 2-1 Neisser’s view of the perceptual cycle....................................................................22 2-2 Modification of Neisser’s view of the perceptual cycle..........................................22 2-3 Model of situation awareness in dynamic decision-making. Adapted from Endsley, M. (1995). Toward a theory of situation awareness in dynamic systems.
Load more

Recommended publications
  • Cognitive Correlates of Listening Comprehension
    Cognitive Correlates of Listening Comprehension Young-Suk Kim ABSTRACT In an effort to understand cognitive foundations of oral language compre- Beth Phillips hension (i.e., listening comprehension), we examined how inhibitory control, F l o r i d a S t a t e U n i v e r s i t y , T a l l a h a s s e e , theory of mind, and comprehension monitoring are uniquely related to listen- U S A ing comprehension over and above vocabulary and age. A total of 156 chil- dren in kindergarten and first grade from high- poverty schools participated in the study. Using structural equation modeling, results showed that all three cognitive skills (inhibitory control, theory of mind, and comprehension moni- toring) were positively related to listening comprehension after accounting for vocabulary and age. In addition, inhibitory control had a direct relation to listening comprehension, not indirectly via theory of mind. Results are discussed in light of cognitive component skills for listening comprehension. ral language comprehension is the foundational skill not only in social interactions but also in literacy acquisition (e.g., O Catts, Fey, Zhang, & Tomblin, 1999 ; Snow, Burns, & Griffin, 1998 ). Along with word reading, oral language comprehension is one of the two necessary skills for reading comprehension according to the simple view of reading (Hoover & Gough, 1990 ). Evidence for the role of oral language comprehension in reading comprehension has been demonstrated across languages with varying depths of orthogra- phy, including English, Spanish, Chinese, and Korean (Hoover & Gough, 1990 ; Joshi, Tao, Aaron, & Quiroz, 2012 ; Kendeou, van den Broek, White, & Lynch, 2009 ; Kim, Park, & Wagner, 2014 ; Vellutino, Tunmer, Jaccard, & Chen, 2007 ).
    [Show full text]
  • Fostering and Measuring Skills: Improving Cognitive and Non-Cognitive Skills to Promote Lifetime Success
    Fostering and Measuring Skills: Improving Cognitive and Non-Cognitive Skills to Promote Lifetime Success Tim Kautz, James J. Heckman, Ron Diris, Bas ter Weel, Lex Borghans Directorate for Education and Skills Centre for Educational Research and Innovation (CERI) Education and Social Progress www.oecd.org/edu/ceri/educationandsocialprogress.htm FOSTERING AND MEASURING SKILLS: IMPROVING COGNITIVE AND NON-COGNITIVE SKILLS TO PROMOTE LIFETIME SUCCESS This work is published under the responsibility of the Secretary-General of the OECD. The opinions expressed and arguments employed herein do not necessarily reflect the official views of OECD member countries. This document and any map included herein are without prejudice to the status of or sovereignty over any territory, to the delimitation of international frontiers and boundaries and to the name of any territory, city or area. Photo credits: © Shutterstock You can copy, download or print OECD content for your own use, and you can include excerpts from OECD publications, databases and multimedia products in your own documents, presentations, blogs, websites and teaching materials, provided that suitable acknowledgment of the source and copyright owner is given. All requests for public or commercial use and translation rights should be submitted to [email protected]. Requests for permission to photocopy portions of this material for public or commercial use shall be addressed directly to the Copyright Clearance Center (CCC) at [email protected] or the Centre français d’exploitation du droit de copie (CFC) at [email protected]. ACKNOWLEDGEMENTS This report was commissioned by the OECD through its project on Education and Social Progress. We thank Linor Kiknadze and Edward Sung for valuable research assistance.
    [Show full text]
  • Hierarchy of Cognitive Domain Learning Skills for Activity Design
    Session 1330 HIERARCHY OF COGNITIVE DOMAIN LEARNING SKILLS TO GUIDE ACTIVITY DESIGN, CLASSROOM FACILITATION, AND CLASSROOM ASSESSMENT Steven Beyerlein and Dan Cordon, Mechanical Engineering University of Idaho Denny Davis, Bioengineering Washington State University Cy Leise, Psychology Bellevue University Daniel Apple, President Pacific Crest ABSTRACT Development of a complex set of life-long learning skills in the cognitive, social, and affective domains is an important goal of engineering education. This is complicated by the reality that learning skill development transcends the temporal and spatial boundaries of isolated courses (SCANS 1991). This work responds to the need for a shared language to promote and reinforce learning skill development between courses and across the curriculum. The research question that motivated this work is whether greater specificity in learning skill definition than that prescribed by ABET Criteria 3 and 4 can be a useful tool for daily teaching/learning. This paper outlines the philosophy, organization, and application of a classification of learning skills within the cognitive domain. Over 90 distinct learning skills are grouped into skill clusters that fall within process areas aligned with Bloom's taxonomy. Learning skills within the classification apply from pre-college through graduate study. Candidate skills were inventoried from numerous literature sources and then validated, positioned, and refined through deliberations of an inter-disciplinary focus group. This paper includes a holistic rubric for defining, measuring, and elevating individual learning skills as well as discussion of how targeting specific skills can strengthen activity design, facilitation of learning, and classroom assessment. NEED FOR LEARNING SKILL CLASSIFICATION Educators committed to applying learning theory to classroom practice have long needed a shared language to use in discussing learning skill development.
    [Show full text]
  • Social Cognitive Theory of Personality
    1 SOCIAL COGNITIVE THEORY OF PERSONALITY Albert Bandura Stanford University Bandura, A. (1999). A social cognitive theory of personality. In L. Pervin & O. John (Ed.), Handbook of personality (2nd ed., pp. 154-196). New York: Guilford Publications. (Reprinted in D. Cervone & Y. Shoda [Eds.], The coherence of personality. New York: Guilford Press.) 2 Many psychological theories have been proposed over the years to explain human behavior. The view of human nature embodied in such theories and the causal processes they postulate have considerable import. What theorists believe people to be determines which aspects of human functioning they explore most thoroughly and which they leave unexamined. The conceptions of human nature in which psychological theories are rooted is more than a theoretical issue. As knowledge gained through inquiry is applied, the conceptions guiding the social practices have even vaster implications. They affect which human potentialities are cultivated, which are underdeveloped, and whether efforts at change are directed mainly at psychosocial, biological or sociostructural factors. This chapter addresses the personal determinants and mechanisms of human functioning from the perspective of social cognitive theory (Bandura, 1986). The recent years have witnessed a resurgence of interest in self-referent phenomena. Self- processes have come to pervade diverse domains of psychology because most external influences affect human functioning through intermediary self processes rather than directly. The self system thus lies at the very heart of causal processes. To cite but a few examples, personal factors are very much involved in regulating attentional processes, schematic processing of experiences, memory representation and reconstruction, cognitively-based motivation, emotion activation, psychobiologic functioning and the efficacy with which cognitive and behavioral competencies are executed in the transactions of everyday life.
    [Show full text]
  • Social Cognitive Theory
    1 SOCIAL COGNITIVE THEORY Albert Bandura Stanford University Bandura, A. (1989). Social cognitive theory. In R. Vasta (Ed.), Annals of child development. Vol. 6. Six theories of child development (pp. 1-60). Greenwich, CT: JAI Press. 2 Many theories have been proposed over the years to explain the developmental changes that people undergo over the course of their lives. These theories differ in the conceptions of human nature they adopt and in what they regard to be the basic causes and mechanisms of human motivation and behavior. The present chapter analyzes human development from the perspective of social cognitive theory (Bandura, 1986). Since development is a life- long process (Baltes & Reese, 1984), the analysis is concerned with changes in the psychosocial functioning of adults as well as with those occurring in childhood. Development is not a monolithic process. Human capabilities vary in their psychobiologic origins and in the experiential conditions needed to enhance and sustain them. Human development, therefore, encompasses many different types and patterns of changes. Diversity in social practices produces substantial individual differences in the capabilities that are cultivated and those that remain underdeveloped. Triadic Reciprocal Determinism Before analyzing the development of different human capabilities, the model of causation on which social cognitive theory is founded is reviewed briefly. Human behavior has often been explained in terms of one-sided determinism. In such modes of unidirectional causation, behavior is depicted as being shaped and controlled either by environmental influences or by internal dispositions. Social cognitive theory favors a model of causation involving triadic reciprocal determinism. In this model of reciprocal causation, behavior, cognition and other personal factors, and environmental influences all operate as interacting determinants that influence each other bidirectionally (Figure 1).
    [Show full text]
  • Comparative Developmental Psychology: How Is Human Cognitive Development Unique?
    Evolutionary Psychology www.epjournal.net – 2014. 12(2): 448-473 ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ Original Article Comparative Developmental Psychology: How is Human Cognitive Development Unique? Alexandra G. Rosati, Department of Psychology, Yale University, New Haven, CT, USA. Email: [email protected] (Corresponding author). Victoria Wobber, Department of Psychology, Harvard University, Cambridge, MA, USA. Kelly Hughes, Department of Brain and Cognitive Sciences, University of Rochester, Rochester, NY, USA. Laurie R. Santos, Department of Psychology, Yale University, New Haven, CT, USA. Abstract: The fields of developmental and comparative psychology both seek to illuminate the roots of adult cognitive systems. Developmental studies target the emergence of adult cognitive systems over ontogenetic time, whereas comparative studies investigate the origins of human cognition in our evolutionary history. Despite the long tradition of research in both of these areas, little work has examined the intersection of the two: the study of cognitive development in a comparative perspective. In the current article, we review recent work using this comparative developmental approach to study non-human primate cognition. We argue that comparative data on the pace and pattern of cognitive development across species can address major theoretical questions in both psychology and biology. In particular, such integrative research will allow stronger biological inferences about the function of developmental change, and will be critical in addressing how humans come to acquire species-unique cognitive abilities. Keywords: comparative development, primate cognition, heterochrony, human adaptation ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ Introduction Human behavior is strikingly different from that of other animals. We speak language, routinely cooperate with others to reach complex shared goals, engage in abstract reasoning and scientific inquiry, and learn a rich set of sophisticated cultural behaviors from others.
    [Show full text]
  • The Cognitive Neuroscience of Video Games
    The Cognitive Neuroscience of Video Games C. Shawn Green and Daphne Bavelier To Appear In: “Digital Media:Transformations in Human Communication” Messaris & Humphreys, Eds. December 1, 2004 1 Introduction The Atari video game platform was released in the late 1970’s. Nintendo was born in the early 1980’s. Since then, the percentage of Americans who play video games has grown at an astronomical pace. This explosion has been spurred on by advancements in both hardware technology and software development that allow a more intense and realistic gaming experience. In addition to these improvements in graphical capability, advances in online gaming now allow users to play with sometimes hundreds of others, which is slowly changing the perception of video game play from a solitary to a social activity. The Entertainment Software Association estimates that around 60% of Americans, around 145 million people in all, currently play some type of video game and despite the common view of video games being “for kids,” the average age of a video game player is actually around 29 years old. Unsurprisingly, both popular and scientific interest in the potential consequences of game play has been driven by this dramatic surge in video game use. While the majority of research (and media attention) has focused on the potential for video game play to negatively affect temperament and social behavior, or on the potential to harness video games to help children learn, a subset of cognitive scientists have investigated the effect of video games on the more fundamental question of how people see the world. In most of the biological sciences, the question of nature versus nurture is often debated.
    [Show full text]
  • A Pilot Study of Classroom-Based Cognitive Skill Instruction: Effects
    MIND, BRAIN, AND EDUCATION A Pilot Study of Classroom-Based Cognitive Skill Instruction: Effects on Cognition and Academic Performance Allyson P. Mackey1 , Anne T. Park1,SydneyT.Robinson2,andJohnD.E.Gabrieli3 ABSTRACT— Cognitive skills are associated with academic if students could think more quickly, hold more information performance, but little is known about how to improve in mind, and solve problems more efficiently, they would be these skills in the classroom. Here, we present the results better able to learn in the classroom. Further, curricula and of a pilot study in which teachers were trained to engage standardized assessments are beginning to place a stronger students in cognitive skill practice through playing games. emphasis on cognitive skills. For example, Common Core Fifth-grade students at an experimental charter school were guidelines state that students must “make sense of problems randomly assigned to receive cognitive skill instruction (CSI) and persevere in solving them, reason abstractly and quan- or instruction in geography and typing. Students in the CSI titatively, and evaluate the validity of the reasoning.” Tese group improved significantly more than the control group shifting expectations have led educators to ask the question on a composite measure of cognitive skills. CSI was more of how to best shape and support cognitive skill develop- effective for students with lower standardized test scores. ment in the classroom. Here, we describe the cognitive and Although there was no group effect on test scores, cognitive academic effects of a cognitive skill curriculum that resulted improvement correlated positively with test score improve- from an interdisciplinary collaboration between educators ment only in the CSI group.
    [Show full text]
  • Learning Contexts, Skills and Social Progress: a Conceptual Framework
    2. LEARNING CONTEXTS, SKILLS AND SOCIAL PROGRESS: A CONCEPTUAL FRAMEWORK Chapter 2 Learning contexts, skills and social progress: a conceptual framework This chapter presents a conceptual framework that describes the relationships between learning contexts, skills and social progress. Individuals’ skills are formed in diverse learning environments, including families, schools and communities. Each of these contexts is influenced by direct inputs, environmental factors and policy levers which can be used by decision makers to foster the development of the full spectrum of skills needed for achieving social progress. Social progress includes diverse aspects of individuals’ lives, including education, labour market outcomes, health, family life, civic engagement and life satisfaction. Skills encompass cognitive, social and emotional capabilities needed for achieving prosperous, healthy and happy lives. Social and emotional skills play a particularly important role when individuals pursue goals, work with others and manage emotions. Skills develop progressively, building on previously acquired skills and on new learning investments. Those that start developing skills early tend to achieve more than others, although adolescence is also a key moment for social and emotional skills development. SKILLS FOR SOCIAL PROGRESS: THE POWER OF SOCIAL AND EMOTIONAL SKILLS © OECD 2015 31 2. LEARNING CONTEXTS, SKILLS AND SOCIAL PROGRESS: A CONCEPTUAL FRAMEWORK Introduction This chapter introduces a conceptual framework designed to capture the key mechanisms through which learning contexts, including learning investments, shape individual well-being and societal progress (Figure 2.1).1 This framework, while acknowledging the importance of cognitive skills in driving socio-economic outcomes, sheds light on the role of social and emotional skills, such as the ability to pursue long-term goals, work with others and manage emotions.
    [Show full text]
  • The Nature of the Black-White Difference on Various Psychometric Tests: Spearman's Hypothesis
    THE BEHAVIORAL AND BRAIN SCIENCES (1985) 8, 193-263 printed in the United States of America The nature of the black-white difference on various psychometric tests: Spearman's hypothesis Arthur R. Jensen School of Education, University of California, Berkeley, Calif. 94720 Abstract: Although the black and white populations in the United States differ, on average, by about one standard deviation (equivalent to 15 IQ points) on current IQ tests, they differ by various amounts on different tests. The present study examines the nature of the highly variable black-white difference across diverse tests and indicates the major systematic source of this between- population variation, namely, Spearman's g. Charles Spearman originally suggested in 1927 that the varying magnitude of the mean difference between black and white populations on a variety of mental tests is directly related to the size of the test's loading on g, the general factor common to all complex tests of mental ability. Eleven large-scale studies, each comprising anywhere from 6 to 13 diverse tests, show a significant and substantial correlation between tests' g loadings and the mean black-white difference (expressed in standard score units) on the various tests. Hence, in accord with Spearman's hypothesis, the average black-white difference on diverse mental tests may be interpreted as chiefly a difference in g, rather than as a difference in the more specific sources of test spore variance associated with any particular informational content, scholastic knowledge, specific acquired skill, or type of test. The results of recent chronometric studies of relatively simple cognitive tasks suggest that the g factor is related, at least in part, to the speed and efficiency of certain basic information-processing capacities.
    [Show full text]
  • Cognitive Science Concepts and Technology Teacher Education 33 Dan Brown
    Cognitive Science Concepts and Technology Teacher Education 33 Dan Brown The Journal of Technology Studies In the early 1990s, Johnson (1992a) stated interaction and personal experience into the that technology educators had shown little process of transforming information to interest in cognitive science-based research knowledge (Johnson, 1992a). After which he observed was unfortunate because of examination of accessible cognitive science the close alignment between many concepts literature, I found the literature highlighted the in cognitive science and technology education. following learning theory-based concepts that That may be less true today, but the disconnect seemed to relate directly or indirectly to between being aware of these concepts and/or experiential learning. terms and teaching students to be able to Metacognition. consciously use these constructs to enhance Metacognition collectively consists of the learning is still apparent. It also appears that becoming aware of personally preferred cognitive there is very little research on these cognitive strategies as well as acquiring, employing, and science theories within the context of monitoring new strategies for learning (Johnson, technology teacher education or technical 1992b; West et al., 1991). Also called strategic education in general. thinking, metacognition involves planning, This article explores technology teacher regulating, and evaluating thinking activities. It educators’ perceptions about and use of the includes such strategies as monitoring, questioning, following cognitive science theories: schemata, summarizing, predicting, generating, and mental and graphic visualization, reflection and evaluating alternatives. Knowledge is obtained debriefing, situated learning or cognition, cognitive through identification of relationships and apprenticeship and its component parts modeling, connections. Experiential learning is necessarily coaching and scaffolding, and metacognition.
    [Show full text]
  • Cognitive Ability, Character Skills, and Learning to Play Equilibrium: a Level-K Analysis
    IZA DP No. 8236 Cognitive Ability, Character Skills, and Learning to Play Equilibrium: A Level-k Analysis David Gill Victoria Prowse June 2014 DISCUSSION PAPER SERIES Forschungsinstitut zur Zukunft der Arbeit Institute for the Study of Labor Cognitive Ability, Character Skills, and Learning to Play Equilibrium: A Level-k Analysis David Gill Oxford University Victoria Prowse Cornell University and IZA Discussion Paper No. 8236 June 2014 IZA P.O. Box 7240 53072 Bonn Germany Phone: +49-228-3894-0 Fax: +49-228-3894-180 E-mail: [email protected] Any opinions expressed here are those of the author(s) and not those of IZA. Research published in this series may include views on policy, but the institute itself takes no institutional policy positions. The IZA research network is committed to the IZA Guiding Principles of Research Integrity. The Institute for the Study of Labor (IZA) in Bonn is a local and virtual international research center and a place of communication between science, politics and business. IZA is an independent nonprofit organization supported by Deutsche Post Foundation. The center is associated with the University of Bonn and offers a stimulating research environment through its international network, workshops and conferences, data service, project support, research visits and doctoral program. IZA engages in (i) original and internationally competitive research in all fields of labor economics, (ii) development of policy concepts, and (iii) dissemination of research results and concepts to the interested public. IZA Discussion Papers often represent preliminary work and are circulated to encourage discussion. Citation of such a paper should account for its provisional character.
    [Show full text]