Cerebral asymmetries in processing ianguage and tirne by Lorin J. Elias A thesis presented to the University of Waterloo in mentof the thesis requirement for the degree of Doctor of Philosophy in Psychology Waterloo, Ontario, Canada, 1999 O Lorin J. Elias, 1999 National Library Bibliothéque nationale of Canada du Canada Acquisitions and Acquisitions et Bibliographie Services senices bibliographiques 395 Wellington Street 395, rue Wellington ûttawa ON KIA ON4 OttawaON K1AON4 Canada Canada The author has granted a non- L'auteur a accordé une licence non exclusive licence allowhg the exclusive permettant à la National Library of Canada to Bibliothèque nationale du Canada de reproduce, loan, distribute or sell reproduire, prêter, distribuer ou copies of this thesis in microform, vendre des copies de cette thèse sous paper or electronic formats. la forme de microfiche/nlm, de reproduction sur papier ou sur format électronique. The author retains ownership of the L'auteur conserve la propriété du copyright in this thesis. Neither the droit d'auteur qui protège cette thèse. thesis nor substantial extracts fiom it Ni la thèse ni des extraits subStafltieIs may be printed or otherwise de celbci ne doivent être imprimés reproduced without the author's ou autrement reproduits sans son permission. autorisation. The University of Waterloo requires the signatures of ail persons using or photocopying this thesis. Please sign below, and give address and date. Abstrac t uiitiaüy it was thought that only 'higher functions' are lateralized, but investigators have recently been noting very 'low-lever perceptual asymmetries. Some have speculated that these Io w-level asymmetries underlie hernispheric speciakation for higher hinctio ns such as language processing. Experimenu 1 and 2 tested this hypothesis by administering tests of low-level temporal asymmetries in the visual (1) and auditory (2) modalities, concurrent with a dichotic-listening test of linguistic laterality. As predicted, individuals demonstrated significant left hernisphere advantages (LHAs)on both the visual and auditory temporal tasks, and in both cases, these LHAs correlated signiticantly with linguistic asymmeules. A recent theory by Ringo et ai. (1994) claims that the evolutionary pressure favouring hemisphenc specialization came fiom a lateraiized system's relative superiority at processing stimuli requiring fine temporal precision. This theory would then predict that individuals with greater hterhemispheric transmission tirnes (ms)would exhibit greater lateralization for time cntical tasks such as language processing. Experiment 3 provided support for the prediction that longer IHïTs from the right to left hemisphere in the auditory modality are associated with greater left hemisphenc specialization for linguistic perception. Experiment 4 tested two predictions. The fïrst prediction. that preferred hand for throwing (but no t prefed hand for writing) wouid be associated with linguistic lateraiization, was only supponed by individuals who nodywrite with their right hand. The second prediction, that complementarity of functional asymmetries should not be causal in nature, was also supponed. There was a weak positive association benveen what are normaily right and left hemisphencaily dominateci tasks. Taken together, these results support the position that the brain is lateralized to facüitate temporai processing. Ackno wledgments Although theses are usuaily viewed as the product of one individual's work, they are very rarely completed in isolation. This work was supported by many people. First and foremost, 1 wish to express my appreciation and thanks to rny advisors Dr. M.B. Buhan-Fleming and Dr. I.C. McManus for their guidance, patience, and tireless advice throughout the entire course of this work. 1 am also very thanldul to the nst of my examination committee for their thorough review of this document and excellent comments. In addition to my advisors Dr. M.B.Bulrnan-Fleming and Dr. I.C. McManus, the cornmittee was composed of Dr. M.J. Dixon, Dr. E.A. Roy, Dr. A. Patla, and Dr. M. Moscovitch. 1 would also like to thank Murray Guylee for his assistance and fkiendship. Through his unrelenthg enthusiasm and dedication, 1 was regularly rerninded that experirnental psychology be fun, and that is why 1 chose this field of study in the first place. Without his help and demeanor, this work simply could not have been completed in such a timely fashion, nor would it have been nearly as much fun. Although her academic contributions to thû work were minimal, 1 am ako very grateful to rny wife Lana for her support during the past years. One of the few things that is more difncult than trying to complete a thesis is king marrieci to someone trying to complete a thesis. She has always ken a very powemil motivating force in my life, and held everythmg together when 1 did not. Orhers who provided personal and academic support (or much needed distractions) during the course of this work include Greg Sears (who mostly provided distraction), Geoff MacDonald (again, mostly distraction), Jocelyn Keillor (who was always so smart in ways that 1 didn't think were important in academia, until she showed me how wrong 1 was), and Mike Dixon (who showed me that sometirnes it is more important to shoot baskets than work on research). 1 would also Iüce to thank the people who panicipated in tbese experiments for their patience and their interest. Many of the tests 1 administered get to be very tedious, but most participants were extremely pleasant and patient. Although Phil Bryden never got to see these experiments cornpleted, 1 wül forever wonder what he would have thought of them. Getting to know hirn profoundly altered the way 1 think about designing experiments, interpreting the expeerimental literature, what a student-advisor relationship should be like, what makes a for a successful scholarly conference, and how to combine an acaciemic career with a happy Ne. Dedication To Phi1 Bryden 1934 - 1996 Table of Contents Theories about the cause of laterality ............................................ .2 A Envir onmentaVPsychosocial Theories ....................................2 1. Jackson's (1905) "Parental Pressure" Theory ......................... -3 2. Blau's (1946) Psychodynamic Theory ............................. -4 B.GeneticTheories ................................................... -5 1. Simple Mendelian Recessive Gene Theories ..........................7 - 2. McManus's (1985) Mode1 ....................................... -8 3. Annett's (1972) Right Shift Model.. .............................. -8 4. Klar's "'RGHT"(1996) Mode1 ................................... .9- 5. Levy and Nagylacki's (1972) Two Gene-Locus Model ................ C. Anatomical Theories ................................................ -12 1. Thomas Carlyle's "Sword and Shield" Theory ....................... 2. Salk's (1966) "Parent Holding Baby" Theory ........................ -14 D. Developmental Theories .............................................II 1. Geschwind and Galaburda's (1987) 'Triadic" theory .................. & 2. The "Pathological Lefi-handedness" theory ......................... a 3. Previc's (199 1. 1996) "Vestibular-Monoaminergic" theory ............. 2 4. Corballis and Morgan's (1978) 'Maturational Gradient" theory .......... 30 5. The "Developmental Instability" theory ............................ -32 6. The "Vanishing Twins" theory .................................. -22 E.EvolutionaryTheories ............................................... 2 l.Corballis(1991) ..............................................38 2. MacNeilage's (1991) "Postural Origins" theory ......................-39 3. The Interhemispheric Conduction Delay Hypothesis .................. -41 ExperimentalSection ........................................................ 48 Predictionl .........,..........................................-....48 - Experimentl ..................................................4 Method ................................................ 32 Participants ........................................ 2 Materials: ......................................... 32 Procedure .........................................3s ScoringandAnalysis ................................. 26 Resdts ................................................. 52 Inspection-timetask .................................57 - Dichotic-listening ta& ................................ 32 Tests of Association Between the two Taskx ............... 5), Discussion .............................................. 62 Experiment2 ..................................................65 - blethod ..,........................................-.....66- Participants ........................................66- Materiais ..........................................67- Procedure .........................................@ ScoringandAnalysis .................................fi Results .................................................70- Dichotic-listening task ............................... -70- Gap-Detection task .................................. LI Tests of Association Between the two Tasks ...............x .Discussion .............................................. 76 Prediction 2: Longer ICD's should be associated with greater linguistic laterality .....&Q Experiment3 .................................................. Method ................................................. 82 Participants ........................................ Q Materiais ..........................................u