Middle-East Journal of Scientific Research 8 (1): 288-293, 2011ISSN 19 - PDF document

Middle-East Journal of Scientific Research 8 (1): 288-293, 2011ISSN 1990-9233© IDOSI Publications, 2011Corresponding Author:Rosemary B. Bassey, Department of Anatomy, College of Medicine, University of Lagos, P. M. B. 12003, Idi-araba, Lagos-Nigeria. Tel: +234-8064853304, E-mail: rosemary_bassey@yahoo.com.288The Prevalence of Left-Handedness among Medical and Dental Students in the University of Lagos-NigeriaOremosu Ademola, Odeyemi Kofoworola, Oremosu Omotayo, 123 Handedness MBBS BDS StudentsINTRODUCTIONduringpregnancy, low birth weight, diffuse brain damage Middle-East J. Sci. Res., 8 (1): 288-293, 2011289connective material could allow more rapid communicationStatistical Analysis: Questionnaires were coded andbetween the hemispheres and hence more rapid andstatistical analysis was done using Statistical Package forefficient processing of certain information.Social Sciences software programme (SPSS) Version 10 toDespite scientific causes of handedness,incalculate frequencies and chi-square analysis to test formanycultures of the world, different other causesassociations between categorical variables.have been attributed to left-handedness. Inaresearch carried out in the Northern part of Nigeria,RESULTSit was found that almost half of the respondents agreedwiththe idea that left-handedness is geneticallySocio-Demographic Characteristics: A total of 512determined [7]. Most of the men in the Southern part ofstudents participated in this survey and the age by sex ofNigeria believed that left-handedness occurs as a result ofthe participants are shown in Table 1. parents’ laziness or carelessness in their child rearingThe majority of the students who took part in thispractices, while women believed that left-handednesssurvey were males with their number at 290 whenoccursas a result of some medical problems duringcompared to females who were 222. Their ages rangedpregnancy [7]. from 17 to over 27 years with a median age of 21. TheThepresent survey is therefore designed to assesshighest number of respondents belonged to the 21 -22 agetheprevalence of left-handedness among medicalrange with a total of 215 out of 512. students in the University of Lagos using a questionnaireThe majority of the students who took part in thissurvey which is manifestly concerned with left-survey were males with their number at 290 whenhandedness in relation to age, sex and ethnicity.compared to females who were 222. Their ages rangedMATERIALS AND METHODShighest number of respondents belonged to the 21 -22 ageStudy Population: The survey was carried out in June,Acording to figure 1, the highest percentage of left-2010 among 512 medical (MBBS) and dental (BDS)handed students were of the 19-20 age range with 25.9%,students of the University of Lagos.followed 23.8% for those in the 17-18 age range, 19.5% forSurvey Instrument:The questionnaire soughtagerange, 18.8% for those in the 25-26 age range and theinformation on their socio-demographic characteristicsleast coming from those in the 27 age range (8.7%).and hand preference for different activities. Comparing the difference in handedness for each ageThis was donein the form of a self-group, those in the age range 19-20 had the highestadministered questionnaire which was distributed topercentage with 25.9% who were left-handed and 74.1%them through their classes. Names were not requiredwho were right handed, followed by 17-18 age rangetobe written on the questionnaire to ensurehaving 23.8% left handed and 76.2% right handed whileconfidentiality and to prevent likely bias in their responsethose aged 21-22 had 19.5% left handed and 80.5% wereto the questions.right handed; the students in the age range 25-26 hadfrom 17 to over 27 years with a median age of 21. Therange with a total of 215 out of 512. those in the 21-22 age range, 18.1% for those in the 23-24Table 1: Age by Sex Distribution of StudentsFrequency (%)---------------------------------------------------------Male (n=290)Female (n=222)Total (n=512)Students' T-statisticAGE17-1818 (6.2)24 (10.8)42 (8.2)5.24,� 0.00*19-2048 (16.6)64 (28.8)112 (21.9)21-22120 (41.4)95 (42.8)215 (42.0)23-2449 (16.9)23 (10.4)72 (14.1)25-2637 (12.8)11 (5.0)48 (48.0)18 (6.2)5 (2.3)23 (4.5)Total290 (100)222 (100)512 (100)Mean Age22.2±2.920.9±2.321.6±2.7Median Age*Significant Middle-East J. Sci. Res., 8 (1): 288-293, 2011290Fig. 1: Percentage of Left Handed Students in Relation to AgeFig. 2: Percentage of Left-handed Students According to SexTable 2: Distribution of Students by Course and Level FrequencyPercentCourseMBBS77.7BDS22.3Level37.119.716.410.416.4Total18.8% who were left-handed and 81.3% who were rightIn Table 2, 77% (398) of the respondents werehanded. The students aged 23-24 had 18.1% who weremedical (MBBS) while 22.3% (114) were dental (BDS)left-handed and 81.9% who were right handed. Those instudents. The respondents from the different levelsthe agerange 27 had the least with 8.7% left-handlersvaried: the highest being 37.1% (190) from the 200 level,and 91.3% right handed students.19.7% (109) from 300 level, 16.4% (84) from 400 and 600According to figure 2, the highest percentage oflevels and the least being 10.4% (53) from 500 level asstudents who were left-handed in this survey were malesshown in Table 2.with22.4% (65) being left handed and 77.6% (225) rightAccording to Table 3, there were 78% left handedhanded;while only 18.8% (40) of the females were left-MBBS students and 21.9% BDS students with an oddhandedand the highest percentage of students who wereratio showing that MBBS students were 3 percent moreright handed were females at 82% (182).likely to be left handed than BDS students. Middle-East J. Sci. Res., 8 (1): 288-293, 2011291Fig. 3: Frequency of Left Handed Students in Relation to EthnicityTable 3: Distribution of Courses and Levels of Respondents by Whether They Are Left HandedLeft Handed (%)95% CI------------------------------------------------------------------------------------------------------Left-handed (N=105)Right-handed (N=407)Total (N=512)Odd RatioLowerUpperCourseMBBS82 (78.1)316 (77.6)398 (77.7)0.591.78BDS23 (21.9)91 (22.4)114 (22.3)0.971.68Level38 (36.2)152 (37.3)190 (37.1)0.591.5230 (28.6)71 (17.4)101 (17.4)1.123.1910 (9.5)74 (18.2)84 (18.2) 0.47*0.220.999 (8.6)44 (10.8)53 (10.4)0.770.341.7218 (17.1)66 (16.2)84 (16.4)1.070.581.96 *SignificantTable 4: Prevalence of Left Handedness for Various Activities According to SexFrequency (%)95% CI-------------------------------------ODD----------------------------------------ActivitiesMaleFemaleTotalRatioLowerUpperWriting23 (7.9)9 (4.1)32 (6.3)2.040.084.86Drawing21 (7.2)9 (4.1)30 (5.6)1.850.794.45Throwing30 (10.3)11 (5.0)41 (8.0) 2.21*1.044.82Using Scissors23 (7.9)9 (4.1)32 (6.3)2.040.884.86Using Toothbrush27 (9.3)12 (5.4)39 (7.6)1.800.853.86Using Knife28 (7.9)15 (6.8)43 (8.4)1.470.742.98Using Spoon10 (10.3)11 (5.0)41 (8.0)0.670.261.77Using Broom31 (10.7)17 (7.7)48 (9.4)1.442.81Striking Match28 (9.7)11 (5.0)39 (7.6)2.050.954.49Opening Box30 (10.3)18 (8.1)48 (9.4)1.312.52Holding Mouse20 (6.9)13 (5.9)33 (6.4)1.190.552.60Using Key27 (9.8)12 (5.4)39 (7.6)1.800.853.86Holding Hammer25 (8.6)11 (5.0)36 (7.0)1.810.834.02Holding Brush/comb32 (11.0)13 (5.9)45 (8.8)1.990.984.12Holding Cup34 (11.7)18 (8.1)52 (10.2)1.510.802.87*Significan Middle-East J. Sci. Res., 8 (1): 288-293, 2011292Thehighest percentage of left handed students werefemales. This is also consistent with previous studies.from200level (36.2%), followed by those from 400 levelThe difference could also have been influenced by the(18.2%), then 300 level (17.4%), 600 level (16.2%);the leasthigher number of males who participated in this survey.was from 500 level.Most of the left-handed students were Yoruba andFromthe odd ratio, 300 and 600 level students werethis could be due to the fact that about 71% of themore likely to be left handed than right handed; unlike thestudents who participated in this survey are Yoruba; andother levels in which the students were more likely to beso no conclusions can be drawn on the prevalence of leftrighthanded than left handed. The likelihood washandedness in relation to ethnicity. Also, while handhowever, significant in the 300 and 400 level students.preference can be affected by social environment, it isAccording to figure 3, the frequency of left-handedunlikely that it is determined entirely by culture. Ifwashigher among Yoruba (70), followed by Ibo andhandedness is socially constructed, one might expect atHausa which showed the same frequency (16); whileleast one culture where left-handedness predominates andOthers showed the least frequency in left handednessthere do not appear to be such a case.with only 3 students.The assessment and analysis of handedness wasPrevalence of Left Handedness: The activities used toPeopledo differ in the extent to which their right or leftdetermine handedness was adapted from Oldfield [8]:hand dominates in manual activities, however and there is“The assessment and analysis of handedness: thean increasing tendency to classify individuals alongaEdinburgh inventory”. Each activity was designed tocontinuous dimension of hand preference for variousassess the hand preference of each student by usingtasks such as writing, throwing, drawing, sewing, toothevery day activities.brushingor opening a lid [10]. The males had a higherTable 4 shows the frequency in which each sextendency of using their left hands to perform theseperformed the various activities with their left hand. Thisactivities than the females.was seen to be higher in males than in females. From the odd ratio, the males were twice likely to useREFERENCEStheirleft hand in writing, throwing which is significant;usingtoothbrush and striking match than the females.1.Gursoy, R., 2009. Effects of left- or right-handThe males were also more likely, though by a smallerpreference on the success of boxers in Turkey. Br. J.percentage, to use their left hand in drawing, usingSports. Med., 43: 142-144.toothbrush,knife and broom, opening box, holding2.Dada, M.F., 2000. Attitude towards left-handednessmouse,using key, holding hammer, brush/ comb and cup.as perceived by selected secondary school studentsThe females were however, more likely to use theirinKogi State. Unpublished M.Ed. thesis, Universityleft hand to use a spoon than males.of Ilorin, Kwara State, Nigeria. DISCUSSIONAspects of Left-handedness. Australian J. Basic andIn this paper, we investigate the prevalence of left4.Milenkovi ,S., D. Rock, M. Dragovi and A. Janca,handedness among medical and dental students of the2008. Season of birth and handedness in Serbian highUniversity of Lagos.school students. Annals of General Psychiatry, 7: 2.The result of this study revealed a decrease in5.Brooks, R., L.F. Bussie`re, M.D. Jennions andprevalence of left handedness with increasing age andJ. Hunt, 2003. Sinister strategies succeed at thelevel of study. The increase of right hand writing with agecricket World Cup. Proc. R. Soc., B, 271: 64-6.suggested that left handed subjects had switched hand6.Llaurens, V., M. Raymond and C. Faurie, 2009. Whypreference [9], most likely because of society pressure.are some people left-handed? An evolutionaryThere however appears to be a diminishing tendency, inperspective. Phil. Trans. R. Soc., B, 364: 881-94.recentyears for left handed children to be forced to write7.Adeoye, E.A. and M.F. Dada, 2000. Causes of andwith their right hand.problems associated with left-handedness asThe percentage of students who were found to beperceived by medical and non-medical students atleft-handed in this survey was higher in males thanthe University of Ilorin. Ilorin J. Education, pp: 1-13.done using the Edinburgh inventory by Oldfield, [8].3.Alibeik, H. and S.A. Angaji, 2010. DevelopmentalApplied Sci., 4: 877-81. Middle-East J. Sci. Res., 8 (1): 288-293, 20112938.Oldfield, R.C., 1971. The assessment and analysis10.Singh, R. and A.R. Singh, 2003. Handedness andof handedness: the Edinburgh inventory.Gender Differences in Spatial Abilities.Neuropsychologia, 9: 97-113.Anthropologist, 5: 113-8.9.Galobardes, B., M.S. Bernstein and A. Morabia, 2001.Can the declining prevalence of left-handedness withage be due to smoking? Am. J. Public Health,89: 352-3.