Intrahemispheric competition between vocal and unimanual performance in right-handed, left-handed and inverted left-handed subjects

This work is dedicated to the _ memory of my grandfather, Angus james Cnpipbell, who .shared 'with nie the special skills' of his many years, and encouraged the pursuit of'academic achievement.> ■ ■'Ï ; ^ ■ AbSTKACT ■ ' • .• .L c v y 'tir)d Kcld 0 976, 1978) propose that, invo'rlocl loft handers, that .Is, • h ' those Icf t-handcps .vho.write with the tip of I heir pen pointed towartls the -' ' bottom of the page, demongtrate ipsilrtleral hemispheric, control over distal musctilature responding.This theory of cerebral organization has not betn well supported by empirical^ evidence, partly because of the failure of ntany -studies ■ to examine the com.plete musculature siystem involved in writing.The present • stpdy w'as proposed to study more of the niusculatUçe'system involved in waiting ' . in the context of performing a dual task., K inslxjurne and .Cooke's (1971) tnodel of Intrahemispheric competition stales that dual task, performance, compared to .single task .performance,will decrease .( 1) .as thé two comi>etltive • functions share the same cerebral space, and (2)', as the-concurrent activit.yincreases in complexity.The -tlfeory further atatcs that .dualtask performance will increase with practice.■ ./ Controlling for Familial .Sinistrality, the present study compared the performance of right banded (n=20), left hancled {n=20) and inverted left handed • \ ' ' '' " -' -(n=20) male subjects during a Pursuit Rotor.Test, wiilch-was hypothesized to J , .parallel so'ine of tlie -motor behaviors involved in writing.Subjects completed .thistàsk while rcniaining.silentor wliile repeating .either a four word phrase or ' • .a four word alliteration.Considering bevy and Reid's (1976, 1978) theory, it was hypothesized that (1) the performance of inverted left handefs dll.H) yithout a history of.F amilial , Sinistrality would shbw.decrenients in responding with their left hand under iwth .interference, conditions.-Ibllsubjects with.ahisto.ryof.;Fa.niillalSinistrality wpre -.predicted to.demonstrate right hand, response decrements during l>oth interference' conditions.(11) left handed (bli) subjects without a history, of , Familial Sinistrality were .predicted to demonstrate a right .handresponse' . .' .' . .' ■ ■ ' ' ill ■ ' .' ' ^ ' ' : " M I'r' decrement under both levels of the interference icondition^, whereas LH with à " ^ ^ .\ ; ^ ' ' ' ' ' history of familial.Sinistrality were expected to show decreased left hand 'responding under i)oth-interferençe conditions.(Ill) Both right handed (Rii) • groups of subjects were proposed t o , demonstrate right hand decrements (n responding pnder iwth interference conditions.The R if grOup-with a history of Familial Sinistrality was also, predicted, to dcnipnstrate a. smaller left hand decrement under Ixjth the interference conditions.Based Upon Kinsbourne and ■ ' • .■ ' ' ■ ■ ' ■ ■ -' / ■Cooke's (1971) dual-code theory, ix>th interference conditions were hypothesized to interfere with and decrease the motor performarjce of subj<-cts uiider the ■ conditions listed in 1, I I and 111 above.It was hypothesized that the alliteration condition would decrease the performance more than the simple phrase .condition.' .■ '/ ■ -Overall, the results.didriot supporL'the predictions Ixised upon bevy and Reid (1976, 1978) hypothesis'.. Neither group of left handed subjects (LH & 11.11) ■ ■ ■ • ./ ' V -' ' -f ' V -' V ''.,1A C K N O W L E D G M E N T i' . 1 .I vÀsh to oppress my appreciation of Dr. Victor Calapp as faculty advisor, critic, and also for providing support, when problems arose.I aiti also fndci)ted to my otiter coni' mittce members, namely Dr.' I