Adult sequential bilingualism and its impact on executive functions: a study on Russian – English bilinguals This thesis is submitted in partial fulfilment of the Honours degree of Bachelor of Psychology (Honours) School of Psychology University of Adelaide October 2018 Word Count: 8957 Table of Contents LIST OF TABLES AND FIGURES ........................................................................................................ III ABSTRACT ............................................................................................................................................... IV DECLARATION ........................................................................................................................................ V ACKNOWLEDGEMENTS ...................................................................................................................... VI INTRODUCTION ....................................................................................................................................... 1 1.1 PREAMBLE .......................................................................................................................................... 1 1.2 BACKGROUND ON LANGUAGE AND BILINGUALISM ......................................................................... 1 1.3 DEFINITION OF BILINGUALISM ......................................................................................................... 2 1.3.1 Natural bilingualism ..................................................................................................................... 3 1.3.2 Sequential bilingualism ................................................................................................................ 3 1.3.3 Balanced verses unbalanced bilingualism .................................................................................... 5 1.4 DISADVANTAGES OF BILINGUALISM ................................................................................................. 5 1.5 ADVANTAGE OF BILINGUALISM: EXECUTIVE FUNCTIONS .............................................................. 6 1.6 CURRENT STUDY ................................................................................................................................ 9 1.6.1 Aims of the study ....................................................................................................................... 10 METHOD .................................................................................................................................................. 11 2.1 PARTICIPANTS .................................................................................................................................. 11 2.2 MATERIALS ...................................................................................................................................... 11 2.2.1 Demographic information .......................................................................................................... 12 2.2.2 The Simon Task ......................................................................................................................... 12 2.2.3 Tower of London Task ............................................................................................................... 13 2.2.4 The Trail Makng Task ................................................................................................................ 13 2.2.5 Wisconsin Card Sorting Task .................................................................................................... 15 2.2.6 The Stroop Colour Word Task ................................................................................................... 16 2.3 PROCEDURE ...................................................................................................................................... 17 2.4 ETHICAL CONSIDERATIONS ............................................................................................................. 17 2.5 DATA ANALYSIS ................................................................................................................................ 18 RESULTS .................................................................................................................................................. 19 3.1 THE SIMON TASK ............................................................................................................................. 21 3.2 TOWER OF LONDON TASK ............................................................................................................... 21 3.3 THE TRAIL MAKING TASK .............................................................................................................. 22 3.4 WISCONSIN CARD SORTING TASK .................................................................................................. 23 3.5 THE STROOP COLOUR WORD TASK ............................................................................................... 25 3.6 PARTICIPANT'S LEVEL OF EDUCATION .......................................................................................... 25 DISCUSSION ............................................................................................................................................ 27 4.1 STUDY OVERVIEW ............................................................................................................................ 27 4.2 SUMMARY OF FINDINGS ................................................................................................................... 27 4.3 FINDINGS IN CONTEXT OF PAST RESEARCH ................................................................................... 28 4.4 SIGNIFICANCE .................................................................................................................................. 31 4.5 LIMITATIONS .................................................................................................................................... 33 4.6 SUGGESTIONS FOR THE FURTHER RESEARCH ............................................................................... 36 4.7 FINAL CONCLUSION ......................................................................................................................... 38 REFERENCES .......................................................................................................................................... 40 APPENDICES ........................................................................................................................................... 44 ii List of Tables and Figures Table 1. Characteristics of monolingual/bilingual participants (N = 94) including age, gender, highest level of education.............................................................................................. 9 Table 2. Descriptive statistics summarising participant scores on the five executive function tasks by group, means, standard deviations, medians and the effect size (monolinguals vs bilinguals)…............................................................................................................................... 10 Table 3. Expected and actual numbers of participants in each group by level of education... 26 Figure 1. The Simon Task (two examples on the right show incongruent stimuli, and congruent stimuli on the left)….................................................................................................. 12 Figure 2. The Tower of London Task – the initial state on the left and the final state on the right, participants drag the balls, using the computer mouse…..……..…........................ 13 Figure 3. Trail Making Task part A, consisting of encircled numbers from 1 to 25 randomly spread across a sheet of paper, the task is to connect the numbers in order in as little time as possible....................................................................................…................................................ 14 Figure 4. Trail Making Task part B, the task is to connect numbers and letters in an alternating pattern (1-A-2-B, etc.) in order in as little time as possible........................................................ 15 Figure 5. The Wisconsin Card Sorting Task (the Test Card at the bottom of figure needs to be placed into the correct category by shape, colour or number)....................................................... 16 Figure 6. The difference in reaction time on the Simon Task between monolingual and bilingual participants.................................................................................................................... 21 Figure 7. The difference in completion time on Trail Making Task part A between monolingual and bilingual participants............................................................................................................. 22 Figure 8. The difference in completion time on Trail Making Task part B between monolingual and bilingual participants............................................................................................................. 23 Figure 9. Median difference in total number of errors between the two language groups on the WCST................................................................................................................................ 24 Figure 10. Median difference in perseverations numbers of errors between the two language groups on the WCST.................................................................................................................... 24 Figure 11. The