The roles of individual differences and working memory in episodic memory The University of Toledo The University of Toledo Digital Repository Theses and Dissertations 2013 The roles of individual dif[.]
The University of Toledo The University of Toledo Digital Repository Theses and Dissertations 2013 The roles of individual differences and working memory in episodic memory Aparna A Sahu The University of Toledo Follow this and additional works at: http://utdr.utoledo.edu/theses-dissertations Recommended Citation Sahu, Aparna A., "The roles of individual differences and working memory in episodic memory" (2013) Theses and Dissertations Paper 193 This Dissertation is brought to you for free and open access by The University of Toledo Digital Repository It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of The University of Toledo Digital Repository For more information, please see the repository's About page A Dissertation entitled The Roles of Individual Differences and Working Memory in Episodic Memory by Aparna A Sahu Submitted to the Graduate Faculty as partial fulfillment of the requirements for the Doctor of Philosophy Degree in Experimental Psychology _ Stephen D Christman, Ph.D., Committee Chair _ John D Jasper, Ph.D., Committee Member _ Kamala London, Ph.D., Committee Member _ Jason Rose, Ph.D., Committee Member _ John McSweeny, J.D., Ph.D., Committee Member _ Patricia R Komuniecki, Ph.D., Dean College of Graduate Studies The University of Toledo May 2013 Copyright 2013, Aparna A Sahu This document is copyrighted material Under copyright law, no parts of this document may be reproduced without the expressed permission of the author An Abstract of The Roles of Individual Differences and Working Memory in Episodic Memory by Aparna A Sahu Submitted to the Graduate Faculty as partial fulfillment of the requirements for the Doctor of Philosophy Degree in Experimental Psychology The University of Toledo May 2013 Past studies on strength of handedness, an individual difference variable, and working memory (WM) have shown their independent associations with episodic memory The current study aimed to check for the associations between these three factors, in addition to assessing the role of strength of handedness in simple and complex WM tasks (measured by digit span and letter number sequencing tasks, respectively) and episodic memory (measured by verbal paired associates) Results revealed robust handedness differences in episodic memory echoing findings from a host of past studies, however, failed to show a significant association with WM Further, a path model was attempted to check if handedness mediated via WM to influence episodic memory retrieval Results revealed that the two were dissociated from one another and yet significantly affected episodic memory The current findings are explained in the light of past evidence that support the roles of WM and handedness in encoding and retrieving episodic memories, respectively iii Acknowledgements My sincere gratitude and thanks to my mentor, Dr Christman, for his constant support and encouragement, and to all committee members for their suggestions, comments and critical questions for this study I am also appreciative of Dr Noela Haughton for offering guidance in applying the statistical model to the current study I thank the students of UT for participating in this study and being a part of this academic endeavor Heartfelt thanks to my support system - friends in the department and across the globe, who extended a helping hand and a listening ear when in need; and family members for their continued faith in me iv Table of Contents Abstract iii Acknowledgements iv Table of Contents v List of Tables vii List of Figures viii List of Abbreviations ix List of Symbols x I Episodic Memory A Introduction B Individual Differences in Episodic Memory II Working Memory A Introduction 11 B Role of Working Memory in Episodic Memory 13 C Individual Differences in Working Memory 15 III Rationale for the Study 18 IV Hypotheses 20 V Methods 22 VI Statistical Analyses 26 VII Results 32 VIII Discussion 50 IX Conclusions 61 v X Limitations 62 XI Future Directions 64 References 65 vi List of Tables Table Descriptive statistic data of the measured variables (N = 207) .33 Table Mean (SD) of the outcome variables used in the study factored by handedness groups (N = 207) .37 Table Correlation between the episodic memory variables (N = 207) 40 Table Mean and standard deviations and bivariate correlations between variables for the proposed Path analysis model (N = 207) 42 Table Mean (SD) of working memory tasks and strategies factored by handedness groups .48 vii List of Figures Figure Gender differences on mean scores of complex WM as measured by the Letter number sequencing task (LNS) .36 Figure Mean scores across the immediate (T1 to T4) and delayed recalls for the VPA task between handedness groups 38 Figure Gender differences on mean scores on trial one and delayed recall on Verbal paired Associates (VPA) .39 Figure Proposed Path model 41 Figure Path model with standardized estimates 43 Figure Re-specified Path model with standardized estimates .45 viii List of Abbreviations AMOS Analysis of Moment Structures ANOVA .Analysis of Variance CFI .Comparative Fit Index C.R Critical Ratio CVLT-II .California Verbal Learning Test – Second Edition DS Digit Span EHI .Edinburgh Handedness Inventory EEG Electroencephalogram ERP Event Related Potential HERA .Hemispheric Encoding Retrieval Asymmetry IBM International Business Machines Corp LNS Letter Number Sequencing LTM Long Term Memory MI .Modification Indices/Index MLE Maximum Likelihood Estimation PA Path Analysis PET Positron Emission Tomography PFC Prefrontal Cortex RMSEA Root Mean Square Error of Approximation SAM Search for Associative Memory SD Standard Deviation SE .Standard Error SEM Structural Equation Modeling STM Short Term Memory TLI .Tucker – Lewis Index VPA Verbal Paired Associates WAIS-IV Wechsler Adult Intelligence Scale – Fourth Edition WM Working Memory WMS Wechsler Memory Scale WMS-III Wechsler Memory Scale – Third Edition WMS-IV Wechsler Memory Scale – Fourth Edition ix References Alipour, A., Aerab-Sheybani, K., & Akhondy, N (2012) Effects of handedness and depth of processing on the explicit and implicit memory Procedia – Social & Behavioral Sciences, 32, 29-33 Arbuckle, J L (2010) AMOS (version 19.0) [Computer Program] Chicago: SPSS Arbuckle, J L (2010) AMOS 19.0 user’s guide Chicago: SPSS Arnsten, A F T (2009) Stress signaling pathways that impair prefrontal cortex structure and function Nature Review Neuroscience, 10, 410-422 Babiloni, C., Vecchio, F., Cappa, S., Pasqualetti, P., Rossi, S., Minuissi, C., & Rossini, P M (2006) Functional frontoparietal connectivity during encoding and retrieval processes follows HERA model: A high resolution study Brain Research Bulletin, 68, 203-212 Baddeley, A D (2000) The episodic buffer: a new component of working memory? 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