Frequency of Left-handed People and Their Creativity in Padang West Sumatera
FREQUENCY OF LEFT-HANDED PEOPLE AND THEIR
CREATIVITY IN PADANG WEST SUMATERA
MEIDILLA DWI SARI
DEPARTEMEN BIOLOGI
FAKULTAS MATEMATIKA DAN ILMU PENGETAHUAN ALAM
INSTITUT PERTANIAN BOGOR
2014
ii
PERNYATAAN MENGENAI SKRIPSI DAN SUMBER
INFORMASI SERTA PELIMPAHAN HAK CIPTA
Dengan ini saya menyatakan bahwa skripsi saya berjudul Frequency of Lefthanded People and Their Creativity in Padang West Sumatera adalah benar karya
saya dengan arahan dari komisi pembimbing dan belum diajukan dalam bentuk
apa pun kepada perguruan tinggi mana pun. Sumber informasi yang berasal atau
dikutip dari karya yang diterbitkan maupun tidak diterbitkan dari penulis lain telah
disebutkan dalam teks dan dicantumkan dalam Daftar Pustaka di bagian akhir
skripsi ini.
Dengan ini saya melimpahkan hak cipta dari karya tulis saya kepada Institut
Pertanian Bogor.
Bogor, Oktober 2014
Meidilla Dwi Sari
NIM G34100106
ABSTRACT
MEIDILLA DWI SARI. Frequency of Left-handed People and Their Creativity in
Padang West Sumatera. Supervised by BAMBANG SURYOBROTO and ALEX
HARTANA.
Handedness is the best-known and most studied human asymmetry. It can
be defined as the individual’s preference to use one hand predominately for
unimanual tasks. Left-handed people are present in every human population but
always comprise a small minority. Some suggest that the structure of the brain of
left-handed and right-handed persons might differ, with a larger corpus callosum
in those who are left-handed. This would be of particular advantage when the
individual was engaged in divergent thinking. This study collect data on the
frequency of left-handed preference and it’s covariation with creativity in
Indonesia. The numbers of respondents in this research are 328 individuals
consisted of 126 males and 202 females in Padang, West Sumatera. In
determining left-handed preference, respondents were asked what hand they
prefer to use of 10 tasks. Determination of creativity used the Adjective Check
List. Frequency of left-handed males in Padang, West Sumatera was higher than
of females. Percentage of creative right-handed males and females is not different,
while for left-handed percentage of creative males is higher than of females. The
results of study showed that only in males does handedness interact with mental
ability lends some support to a possible testosterone link.
Keywords: creativity, handedness, left-handed, padang
ABSTRAK
MEIDILLA DWI SARI. Frekuensi Orang Kidal dan Kreativitasnya di Padang
Sumatera Barat. Dibimbing oleh BAMBANG SURYOBROTO dan ALEX
HARTANA.
Handedness merupakan asimetri manusia yang paling dikenal dan banyak
dipelajari. Handedness dapat didefinisikan sebagai preferensi individu untuk
menggunakan satu tangan yang mendominasi untuk pekerjaan unimanual. Orang
kidal ada di setiap populasi manusia namun selalu terdiri dari minoritas kecil.
Beberapa orang menduga bahwa struktur otak orang kidal dan pengguna tangan
kanan mungkin berbeda, dengan corpus callosum yang lebih besar pada orang
kidal. Ini akan menjadi keuntungan tertentu ketika individu terlibat dalam berpikir
divergen. Penelitian ini mengumpulkan data frekuensi orang kidal dan kovarian
dengan kreatifitas di Indonesia. Jumlah responden pada penelitian ini adalah 328
orang dengan 126 pria dan 202 wanita di Padang, Sumatera Barat. Dalam
penentuan preferensi tangan kiri, responden ditanya tangan mana yang disukai
untuk digunakan dari 10 pekerjaan. Penentuan kreatifitas menggunakan Adjective
Check List. Frekuensi pria kidal di Padang, Sumatera Barat lebih tinggi daripada
wanita. Persentase pria dan wanita pengguna tangan kanan kreatif tidak terlalu
ii
berbeda, sedangkan untuk persentase pria kidal yang kreatif lebih tinggi dari pada
wanita. Hasil penelitian ini menunjukan bahwa hanya pada pria terjadi
interaksi handedness dengan kemampuan mental yang kemungkinan disebabkan
oleh hubungan testosteron.
Kata kunci : handedness, kidal, kreatifitas, padang
ii
FREQUENCY OF LEFT-HANDED PEOPLE AND THEIR
CREATIVITY IN PADANG WEST SUMATERA
MEIDILLA DWI SARI
Skripsi
sebagai salah satu syarat untuk memperoleh gelar
Sarjana Sains
pada
Departemen Biologi
DEPARTEMEN BIOLOGI
FAKULTAS MATEMATIKA DAN ILMU PENGETAHUAN ALAM
INSTITUT PERTANIAN BOGOR
BOGOR
2014
Judul Skripsi : Frequency of Left-handed People and Their Creativity in Padang
West Sumatera
Nama
: Meidilla Dwi Sari
NIM
: G34100106
Disetujui oleh
Dr Bambang Suryobroto
Pembimbing I
Prof Dr Ir Alex Hartana
Pembimbing II
Diketahui oleh
Dr Ir ImanRusmana, M.Si
Ketua Departemen
Tanggal lulus:
vi
PRAKATA
Puji dan syukur penulis panjatkan kepada Allah SWT atas segala rahmat
dan karunia-Nya sehingga karya ilmiah ini berhasil diselesaikan. Karya ilmiah ini
ini disusun berdasarkan hasil penelitian berjudul Frequency of Left-handed People
and Their Creativity in Padang West Sumatera yang berlangsung dari Februari
sampai April 2014.
Terima kasih kepada Dr Bambang Suryobroto dan Prof Dr Ir Alex Hartana
selaku dosen pembimbing atas bimbingan dan saran yang diberikan. Terima kasih
banyak kepada Papa, Ibu, Dai, Niva, dan Mas Adi cinta dan dukungannya. Terima
kasih kepada SMP Negeri 23 Padang dan SMP Negeri 18 Padang yang telah
mengizinkan pengambilan data. Terima kasih juga untuk Lisa dan Tante Is untuk
bantuan dalam pengambilan data dan untuk semua teman-teman Biologi 47 dan
Zoo Corner family untuk bantuan dan dukungan selama ini.
Semoga karya ilmiah ini bermanfaat.
Bogor, Oktober 2014
Meidilla Dwi Sari
viii
DAFTAR ISI
DAFTAR TABEL
x
DAFTAR LAMPIRAN
x
INTRODUCTION
1
Background
1
Aim
2
MATERIALS AND METHOD
2
Time and Place
2
Sample
2
Collecting Personal Data
2
Left-handed Preference
2
Determination of Creativity
2
RESULTS
3
Frequency of left-handed people
3
Creativity
4
DISCUSSION
5
CONCLUSION
6
REFERENCES
6
APPENDIX
7
RIWAYAT HIDUP
11
x
DAFTAR TABEL
1 Percentage of hand prefer and frequency of handedness
2 Percentage of prefer the left hand based on age
3 Percentage of creativity in handedness
4 Percentage of the total scores of ACL
3
4
4
5
DAFTAR LAMPIRAN
1 Research questionnaire
2 Handedness questionnaire
3 Creativity determination
8
9
10
1
INTRODUCTION
Background
Handedness is the best-known and most studied human asymmetry. It can
be defined as the individual’s preference to use one hand predominately for
unimanual tasks and the ability to perform these tasks more efficiently with one
hand (Llaurens et al. 2009). Left-handed people are more skillful with their left
hands when performing tasks. Left-handed people are present in every human
population but always comprise a small minority compared to the large majority
of the population that is right-handed. Left-handedness is found in approximately
10% of the population, but the frequency varies between various human
populations. A study in four societies in Baka, Bobo-Diuolasso, Eipo, and Inuit
had found this frequency ranges from 3.3% to 26.9% (Faurie et al. 2005) and
reviewed 81 studies on handedness in 14 countries in America, Africa, Europe,
Asia and Australia found a range from 5% to 27.5% (Raymond and Pointer 2004).
Hand preference is influenced by genetics, development, and environment
factors. Several genes could influence handedness. Such as LRRTM1 (Leucinerich repeat transmembrane neuronal 1) and PCSK6 (proprotein convertase
subtilisin / kexin type 6) (Scerri et al. 2011). LRRTM1 is expressed during the
development of specific forebrain structures, and thus could influence neuronal
differentiation and connectivity. This is the first potential genetic influence on
human handedness to be identified, and the first putative genetic effect on
variability in human brain asymmetry (Francks et al. 2007). PCSK6 is known to
play a key role in regulating left-right axis specification, making it a highly
attractive candidate gene for involvement in handedness (Scerri et al. 2011).
There are several developmental factors in the womb and birth, including brain
damage resulting from stress during birth that can influence handedness. A surge
of fetal testosterone level during pregnancy can also influence handedness (Tran
et al. 2014). Environmental factors could also exert selection forces on lefthanders. Attitudes towards left-handedness vary from one culture to another.
Cultural and environmental factors could change hand preference (Llaurens et al.
2009).
Some suggest that the structure of the brain of sinistral (left-handed) and
dextral persons might differ, with a larger corpus callosum in those who are lefthanded (Coren 1995). One possible outcome of this exchange might be faster
access to a wider range of memories and associations. This would be of particular
advantage when the individual was engaged in divergent thinking, which moves
outward from conventional knowledge into unexplored association. Divergent
thinkers seem more capable of breaking sets and achieving novel solutions.
Divergent thinking usually produces "original" or "creative" ideas through the
breaking of typical thought sets, the reorganization of materials in uncommon
ways, and the consideration of a wide range of alternative solutions to complex
problems. For this reason divergent thinking is often listed as a major component
of the psychological trait of creativity. Certainly, divergent thinking would
facilitate performance in a number of areas where they appear to excel, such as
art, architecture, mathematics, chess, and so forth (Coren 1995).
2
Aim
The aim of this study is to determine frequency of left-handed people and
their creativity in Indonesia, particularly in Padang, West Sumatera.
MATERIALS AND METHOD
Time and Place
.
The research was held in February until April 2014 in Padang, West
Sumatera. Sampling was conducted in two Junior High School level and door to
door visits. Data was analyzed in Biosystematics and Ecology of Animals
Division, Department of Biology, Bogor Agricultural University.
Sample
The numbers of respondents in this research are 328 individuals consisted
of 126 males and 202 females in Padang, West Sumatera. The number of
respondents from two Junior High School level are 217 individuals. The number
of respondents from door to door visits are 111 individuals. Respondents are
Minangkabau ethnic group.
Collecting Personal Data
Respondents were asked personal information such as name, address,
gender, ethnic group, and recording of peigree of the respondents to determine
family mambers who are left-handed (Appendix 1).
Left-handed Preference
In determining left-handed preference, respondents were asked what hand
they prefer to use to throw a ball, use a spoon, saw, sew, shoot marbles, bowling,
or playing tennis, cut with a knife, cut with scissors, hammer, and write
(Appendix 2). If they routinely use the left hand or either hand for any number of
these 10 tasks, they are designated left-handed preference (Rife 1940).
Determination of Creativity
Adjective Check List (ACL) used to determine creativity of individual
respondents (Gough 1979). Respondents were given a questionnaire containing 30
adjectives and asked to cheklist adjectives that describe themselves (Appendix 3).
In the ACL, there are 30 adjectives that consists of 18 positive items and 12
negative items. In scoring ACL, 1 point given each time one of 18 positive items
is checked, and -1 point given each time one of 12 negative items is checked. The
3
theoretical range of scores is therefore -12 to +18. If respondents had a score ≤ 3
they are categorized as not creative, while a score of > 3 creative (Gough 1979).
RESULTS
Frequency of left-handed people
Percentage of hand prefer and frequency of handedness are shown in
Table 1. Highest percentage of prefer the left hand in males was hammer, while
in females was shoot marbles. Highest percentage prefer the both hands in males
and females were throw a ball. Total frequency of left-handed was 20%.
Frequency of left-handed males was 28% and frequency of left-handed females
was 15%.
Table 1. Percentage of hand prefer and frequency of handedness
Task
Males
Both
4% (5)
Right
83% (105)
6% (8)
2% (2)
92% (116)
Saw
12% (15)
1% (1)
87% (110)
Sew
12% (15)
2% (3)
86% (108)
Shoot
marbles
Bowling or
playing
tennis
Cut with a
knife
Cut with
scissors
Hammer
13% (16)
2% (2)
86% (108)
14% (17)
3% (4)
83% (105)
12% (15)
2% (2)
87% (109)
10% (13)
2% (2)
88% (111)
15% (19)
1% (1)
84% (106)
8% (10)
2% (2)
91% (114)
Throw a
ball
Use a spoon
Write
Frequency
of
handedness
Left
13% (16)
28% (35)
Total
72% (91)
100%
(126)
100%
(126)
100%
(126)
100%
(126)
100%
(126)
100%
(126)
100%
(126)
100%
(126)
100%
(126)
100%
(126)
100%
(126)
Left
8% (16)
Females
Both
2% (3)
Right
91% (183)
5% (10)
1% (2)
95% (190)
7% (15)
0% (0)
93% (187)
8% (16)
1% (1)
92% (185)
11% (23)
0% (0)
89% (179)
7% (15)
1% (1)
92% (186)
9% (18)
1% (1)
91% (183)
8% (16)
0% (0)
92% (186)
8% (17)
0% (0)
92% (185)
5% (11)
1% (1)
94% (190)
15% (31)
Total
85% (171)
( ) : the number of respondents
The respondents who conducted in Junior High School level and door to
door visits were 8-82 years old. The age range 8-18 were 260 individuals, 19-29
were 38 individuals, 30-40 were 13 individuals, 41-51 were 9 individuals, 52-62
were 4 individuals, 63-73 were 2 individuals and 78-84 were 2 individuals.
Percentage of prefer the left hand based on age are shown in Table 2. Highest
100%
(202)
100%
(202)
100%
(202)
100%
(202)
100%
(202)
100%
(202)
100%
(202)
100%
(202)
100%
(202)
100%
(202)
100%
(202)
4
percentage of prefer the left hand were age range 8-18 in all tasks. The age range
30-40, 63-73, and 74-84 were no one left-handed people.
Table 2. Percentage of prefer the left hand based on age
Task
Throw a ball
Use a spoon
Saw
Sew
Shoot marbles
Bowling or playing
tennis
Cut with a knife
Cut with scissors
Hammer
Write
8-18
79% (25)
77% (14)
77% (23)
81% (25)
76% (30)
82% (25)
Age (years)
19-29 41-51 52-62
9% (3)
9% (3)
3% (1)
6% (1) 11% (2) 6% (1)
10% (3) 10% (3) 3% (1)
10% (3) 6% (2)
3% (1)
13% (5) 8% (3)
3% (1)
9% (3)
6% (3)
3% (1)
100% (32)
100% (18)
100% (30)
100% (31)
100% (39)
100% (32)
79% (26)
83% (24)
78% (28)
76% (16)
9% (3)
7% (2)
11% (4)
19% (4)
100% (33)
100% (29)
100% (36)
100% (21)
9% (3)
7% (2)
8% (3)
5% (1)
3% (1)
3% (1)
2% (1)
0% (0)
Total
( ) : the number of respondents
Creativity
ACL scores ranged from -7 to +11. Percentages of creativity in
handedness are shown in Table 3. Percentage of creative right-handed people
(ACL >3) was 36% and percentage of creative left-handed people was 50%. The
creative right-handed males were 39% and creative right-handed females were
35%. The creative left-handed males were 66% and creative left-handed females
were 32%. The result of this research show that percentage of creative males and
females with right-handed preferences is not different , while for left-handed the
proportion of creative males is higher than of females.
Table 3. Percentage of creativity in handedness
Left-handed
Males
Creative Not creative
66% (23) 34% (12)
Right-handed
39% (35)
62% (56)
Total
Females
Creative Not creative
100% 32% (10) 68 (21)
(35)
100% 35% (60) 65% (111)
(91)
Total
100%
(31)
100%
(171)
( ) : the number of respondents
Percentage of the total scores of ACL are shown in Table 4. Highest
percentage of left-handed males on the total score + 4, while for left-handed
females on the total score + 2. Highest percentage of right-handed males on the
total score +2 and +4, while for right-handed females on the total score 0.
5
Table 4. Percentage of the total scores of ACL
Left handed
Total
Score
-7
-6
-5
-4
-3
-2
-1
0
+1
+2
+3
+4
+5
+6
+7
+8
+9
+10
+11
Total
Males
0% (0)
0% (0)
0% (0)
0% (0)
0% (0)
3% (1)
0% (0)
0% (0)
11% (4)
9% (3)
11% (4)
32% (11)
14% (5)
11% (4)
6% (2)
3% (1)
0% (0)
0% (0)
0% (0)
100% (35)
Right handed
Females
0% (0)
0% (0)
3% (1)
3% (1)
3% (1)
3% (1)
7% (2)
7% (2)
16% (5)
23% (7)
3% (1)
10% (3)
3% (1)
3% (1)
10% (3)
3% (1)
3% (1)
0% (0)
0% (0)
100% (31)
Males
1% (1)
1% (1)
0% (0)
2% (2)
1% (1)
3% (3)
12% (11)
5% (4)
11% (10)
15% (14)
10% (9)
15% (14)
12% (11)
7% (6)
5% (4)
0% (0)
0% (0)
0% (0)
0% (0)
100% (91)
Females
0% (0)
1% (1)
1% (1)
2% (3)
1% (1)
2% (4)
8% (15)
9% (16)
13% (22)
16% (28)
12% (20)
11% (18)
11% (19)
7% (13)
3% (7)
1% (1)
0% (0)
1% (1)
1% (1)
100% (171)
( ) : the number of respondents
DISCUSSION
Frequency of left-handed people in Padang, West Sumatera was 20%.
Frequency of left-handed males was 28% and frequency of left-handed females
was 15%. The results showed frequency of left-handed males higher than of
females. The cerebral lateralization theory of Geschwind-Galaburda (Tran et al.
2014) posits that high intrauterine levels of testosterone promote the development
of left-handedness because of differential effects of testosterone on brain
hemisphere maturation; specifically, left brain hemisphere maturation is delayed.
Male brains are exposed to substantially higher testosterone levels than female
brains during prenatal development; hence, a sex effect for handedness may be
expected. Testosterone-induced effects on brain lateralization thus likely take
place early during embryonic development (Tran et al. 2014).
Percentage of creative left-handed people were higher than of righthanded. The result of this research show that percentage of creative males and
females with right-handed preference is not different, while for left-handed
percentage of creative left-handed males is higher than of females. The results of
study showed that only in males does handedness interact with mental ability
lends some support to a possible testosterone link. Obviously, male fetuses are
more likely to be exposed to the higher levels of testosterone than female fetuses.
6
If a dose or effect relationship were involved, this would mean that males are apt
to have the greatest growth in the planum temporale or any other affected areas of
the brain. This means that any benefit derived from changes in the normal pattern
of neurological development would be expected to be more visible in males than
females (Coren 1995).
CONCLUSION
Frequency of left-handed males in Padang, West Sumatera was higher
than of females. Percentage of creative right-handed males and females is not
different, while for left-handed percentage of creative males is higher than of
females.
REFERENCES
Coren S.1995. Differences in divergent thinking as a function of handedness and
sex. The American Journal of Psychology. 108(3): 311-325
Faurie C, Schiefenhövel W, le Bomin S, Billiard S, Raymond M. 2005. Variation
in the frequency of left‐handedness in traditional societies. Current
Anthropology. 46: 142–147.
Francks C, Maegawa S, Lauren J, Abrahams Bs, Velayos-Baeza A, Medland SE,
Colella S, Groszer M, McAuley EZ, Caffrey TM et al. 2007. LRRTM1 on
chromosome 2p12 is a maternally suppressed gene that is
associatedpaternally with handedness and schizophrenia. Molecular
Psychiatry. 12:1129-1139.
Gough HG.1979. A creative personality scale for the Adjective Check List.
Journal of Personality and Social Psychology. 37(8):1398-1405.
Llaurens V, Raymond M, Faurie C.2009. Review Polymorphism of handedness in
humans. Phil.Trans. R. Soc B. 364 : 881-894.
Raymond M, Pontier D.2004. Is there geographical variation in human
handedness?. Laterality. 9(1):35–52.
Rife DC. 1940. Handedness, with special reference to twins. Genetics 25: 178186.
Scerri TS, Brandler WM, Paracchini S, Morris AP, Ring SM, Richardson AJ,
Talcott JB, Stein J, Monaco AP. 2011. PCSK6 is associated with
handedness in individuals with dyslexia. Human Molecular Genetics. 20(3):
608-614.
Tran SU, Stieger S, Voracek M. 2014. Latent variable analysis indicates that
seasonal anisotropy accounts for the higher prevalence of left-handedness in
men. Cortex. 57 :188-197.
7
APPENDIX
8
Appendix 1 Research questionnaire
KUISIONER PENELITIAN
FNUM :
Tanggal
:
Data Pribadi
Nama Lengkap
Jenis Kelamin
Alamat
Suku (Minangkabau)
Kidal
Tempat / Tanggal Lahir
Usia
:
:P/L
:
:
: ya / tidak
:
:
Data Orang Tua
Nama Ayah
Asal
Suku (Minangkabau)
:
:
:
Nama ibu
:
Asal
:
Suku (Minangkabau) :
Nama Ayah dari Ayah
Asal
Suku (Minangkabau)
:
:
:
Nama Ayah dari Ibu :
Asal
:
Suku (Minangkabau) :
Nama Ibu dari Ayah
Asal
Suku (Minangkabau)
:
:
:
Nama Ibu dari Ibu
Asal
Suku (Minangkabau)
Pedigree (silsilah)
:
:
:
9
Appendix 2 Handedness questionnaire
Ceklis ( √ ) tangan mana yang nyaman dan biasa anda gunakan dalam melakukan
kegiatan berikut :
No
Kegiatan
Tangan yang digunakan
Kiri
1
Melempar
2
Bermain bowling / tenis /
bulutangkis
3
Bermain kelereng
4
Memotong dengan pisau
5
Makan dengan sendok
6
Memalu
7
Menggerggaji
8
Menjahit
9
Menulis
10
Menggunting
Kanan
10
Appendix 3 Creativity determination
Ceklis ( √ ) semua sifat dibawah ini yang anda anggap mendeskripsikan diri anda.
___mampu
___jujur
___mudah terpengaruh
___cerdas
___pintar
___sopan
___berhati-hati
___ketertarikan luas
___yakin
___berdaya cipta
___egois
___asli, tidak mencontoh
___lumrah
___ketertarikan sempit
___suka bercanda
___berpikir panjang
___tradisional
___tulus
___tak-bergantung ke orang lain
___banyak akal
___biasa, menurut adat
___percaya diri
___tidak resmi
___sexy
___tidak berpuas-diri
___patuh
___berwawasan
___tinggi hati
___curiga
___tidak biasa, diluar peraturan
Positive and negative items on ACL
Positive
mampu
pintar
yakin
egois
suka bercanda
tak-bergantung ke orang lain
tidak resmi
berwawasan
cerdas
ketertarikan luas
berdaya cipta
asli, tidak mencontoh
berpikir panjang
banyak akal
percaya diri
sexy
tinggi hati
tidak biasa, diluar peraturan
Negative
mudah terpengaruh
berhati-hati
lumrah
tradisional
biasa, meurut adat
tidak berpuas-diri
jujur
ketertarikan sempit
sopan
tulus
patuh
curiga
11
RIWAYAT HIDUP
Penulis lahir di Padang pada tanggal 14 Mei 1992 dari pasangan Ir Sjafri.S
dan Salwati sebagai anak ketiga dari tiga bersaudara. Penulis menyelesaikan
pendidikan di SMA Negeri 2 Padang pada tahun 2010 dan melanjutkan studi pada
Jurusan Biologi, Fakultas Matematika dan Ilmu Pengetahuan Alam, Institut
Pertanian Bogor melalui jalur SNMPTN. Selama mengikuti perkuliahan, penulis
aktif sebagai anggota di Divisi Pamabi (Paguyuban Mahasiswa Biologi)
Himpunan Mahasiswa Biologi (Himabio) IPB pada periode 2011/2012 dan
2012/2013.
Penulis melakukan Studi Lapangan pada tahun 2012 dengan judul
penelitian Keanekaragaman Gymnospermae di Kebun Raya Cibodas. Penulis
melakukan Praktik Lapangan pada tahun 2013 dengan judul Identifikasi Jabon
(Anthocephalus cadamba) dan Nyamplung (Calophyllum inophyllum) sebagai
Sumber Daya Genetik di Unit Pelaksana Teknis Daerah Perbenihan Tanaman
Hutan
Dinas
Kehutanan
Provinsi
Sumatera
Barat,
Padang.
CREATIVITY IN PADANG WEST SUMATERA
MEIDILLA DWI SARI
DEPARTEMEN BIOLOGI
FAKULTAS MATEMATIKA DAN ILMU PENGETAHUAN ALAM
INSTITUT PERTANIAN BOGOR
2014
ii
PERNYATAAN MENGENAI SKRIPSI DAN SUMBER
INFORMASI SERTA PELIMPAHAN HAK CIPTA
Dengan ini saya menyatakan bahwa skripsi saya berjudul Frequency of Lefthanded People and Their Creativity in Padang West Sumatera adalah benar karya
saya dengan arahan dari komisi pembimbing dan belum diajukan dalam bentuk
apa pun kepada perguruan tinggi mana pun. Sumber informasi yang berasal atau
dikutip dari karya yang diterbitkan maupun tidak diterbitkan dari penulis lain telah
disebutkan dalam teks dan dicantumkan dalam Daftar Pustaka di bagian akhir
skripsi ini.
Dengan ini saya melimpahkan hak cipta dari karya tulis saya kepada Institut
Pertanian Bogor.
Bogor, Oktober 2014
Meidilla Dwi Sari
NIM G34100106
ABSTRACT
MEIDILLA DWI SARI. Frequency of Left-handed People and Their Creativity in
Padang West Sumatera. Supervised by BAMBANG SURYOBROTO and ALEX
HARTANA.
Handedness is the best-known and most studied human asymmetry. It can
be defined as the individual’s preference to use one hand predominately for
unimanual tasks. Left-handed people are present in every human population but
always comprise a small minority. Some suggest that the structure of the brain of
left-handed and right-handed persons might differ, with a larger corpus callosum
in those who are left-handed. This would be of particular advantage when the
individual was engaged in divergent thinking. This study collect data on the
frequency of left-handed preference and it’s covariation with creativity in
Indonesia. The numbers of respondents in this research are 328 individuals
consisted of 126 males and 202 females in Padang, West Sumatera. In
determining left-handed preference, respondents were asked what hand they
prefer to use of 10 tasks. Determination of creativity used the Adjective Check
List. Frequency of left-handed males in Padang, West Sumatera was higher than
of females. Percentage of creative right-handed males and females is not different,
while for left-handed percentage of creative males is higher than of females. The
results of study showed that only in males does handedness interact with mental
ability lends some support to a possible testosterone link.
Keywords: creativity, handedness, left-handed, padang
ABSTRAK
MEIDILLA DWI SARI. Frekuensi Orang Kidal dan Kreativitasnya di Padang
Sumatera Barat. Dibimbing oleh BAMBANG SURYOBROTO dan ALEX
HARTANA.
Handedness merupakan asimetri manusia yang paling dikenal dan banyak
dipelajari. Handedness dapat didefinisikan sebagai preferensi individu untuk
menggunakan satu tangan yang mendominasi untuk pekerjaan unimanual. Orang
kidal ada di setiap populasi manusia namun selalu terdiri dari minoritas kecil.
Beberapa orang menduga bahwa struktur otak orang kidal dan pengguna tangan
kanan mungkin berbeda, dengan corpus callosum yang lebih besar pada orang
kidal. Ini akan menjadi keuntungan tertentu ketika individu terlibat dalam berpikir
divergen. Penelitian ini mengumpulkan data frekuensi orang kidal dan kovarian
dengan kreatifitas di Indonesia. Jumlah responden pada penelitian ini adalah 328
orang dengan 126 pria dan 202 wanita di Padang, Sumatera Barat. Dalam
penentuan preferensi tangan kiri, responden ditanya tangan mana yang disukai
untuk digunakan dari 10 pekerjaan. Penentuan kreatifitas menggunakan Adjective
Check List. Frekuensi pria kidal di Padang, Sumatera Barat lebih tinggi daripada
wanita. Persentase pria dan wanita pengguna tangan kanan kreatif tidak terlalu
ii
berbeda, sedangkan untuk persentase pria kidal yang kreatif lebih tinggi dari pada
wanita. Hasil penelitian ini menunjukan bahwa hanya pada pria terjadi
interaksi handedness dengan kemampuan mental yang kemungkinan disebabkan
oleh hubungan testosteron.
Kata kunci : handedness, kidal, kreatifitas, padang
ii
FREQUENCY OF LEFT-HANDED PEOPLE AND THEIR
CREATIVITY IN PADANG WEST SUMATERA
MEIDILLA DWI SARI
Skripsi
sebagai salah satu syarat untuk memperoleh gelar
Sarjana Sains
pada
Departemen Biologi
DEPARTEMEN BIOLOGI
FAKULTAS MATEMATIKA DAN ILMU PENGETAHUAN ALAM
INSTITUT PERTANIAN BOGOR
BOGOR
2014
Judul Skripsi : Frequency of Left-handed People and Their Creativity in Padang
West Sumatera
Nama
: Meidilla Dwi Sari
NIM
: G34100106
Disetujui oleh
Dr Bambang Suryobroto
Pembimbing I
Prof Dr Ir Alex Hartana
Pembimbing II
Diketahui oleh
Dr Ir ImanRusmana, M.Si
Ketua Departemen
Tanggal lulus:
vi
PRAKATA
Puji dan syukur penulis panjatkan kepada Allah SWT atas segala rahmat
dan karunia-Nya sehingga karya ilmiah ini berhasil diselesaikan. Karya ilmiah ini
ini disusun berdasarkan hasil penelitian berjudul Frequency of Left-handed People
and Their Creativity in Padang West Sumatera yang berlangsung dari Februari
sampai April 2014.
Terima kasih kepada Dr Bambang Suryobroto dan Prof Dr Ir Alex Hartana
selaku dosen pembimbing atas bimbingan dan saran yang diberikan. Terima kasih
banyak kepada Papa, Ibu, Dai, Niva, dan Mas Adi cinta dan dukungannya. Terima
kasih kepada SMP Negeri 23 Padang dan SMP Negeri 18 Padang yang telah
mengizinkan pengambilan data. Terima kasih juga untuk Lisa dan Tante Is untuk
bantuan dalam pengambilan data dan untuk semua teman-teman Biologi 47 dan
Zoo Corner family untuk bantuan dan dukungan selama ini.
Semoga karya ilmiah ini bermanfaat.
Bogor, Oktober 2014
Meidilla Dwi Sari
viii
DAFTAR ISI
DAFTAR TABEL
x
DAFTAR LAMPIRAN
x
INTRODUCTION
1
Background
1
Aim
2
MATERIALS AND METHOD
2
Time and Place
2
Sample
2
Collecting Personal Data
2
Left-handed Preference
2
Determination of Creativity
2
RESULTS
3
Frequency of left-handed people
3
Creativity
4
DISCUSSION
5
CONCLUSION
6
REFERENCES
6
APPENDIX
7
RIWAYAT HIDUP
11
x
DAFTAR TABEL
1 Percentage of hand prefer and frequency of handedness
2 Percentage of prefer the left hand based on age
3 Percentage of creativity in handedness
4 Percentage of the total scores of ACL
3
4
4
5
DAFTAR LAMPIRAN
1 Research questionnaire
2 Handedness questionnaire
3 Creativity determination
8
9
10
1
INTRODUCTION
Background
Handedness is the best-known and most studied human asymmetry. It can
be defined as the individual’s preference to use one hand predominately for
unimanual tasks and the ability to perform these tasks more efficiently with one
hand (Llaurens et al. 2009). Left-handed people are more skillful with their left
hands when performing tasks. Left-handed people are present in every human
population but always comprise a small minority compared to the large majority
of the population that is right-handed. Left-handedness is found in approximately
10% of the population, but the frequency varies between various human
populations. A study in four societies in Baka, Bobo-Diuolasso, Eipo, and Inuit
had found this frequency ranges from 3.3% to 26.9% (Faurie et al. 2005) and
reviewed 81 studies on handedness in 14 countries in America, Africa, Europe,
Asia and Australia found a range from 5% to 27.5% (Raymond and Pointer 2004).
Hand preference is influenced by genetics, development, and environment
factors. Several genes could influence handedness. Such as LRRTM1 (Leucinerich repeat transmembrane neuronal 1) and PCSK6 (proprotein convertase
subtilisin / kexin type 6) (Scerri et al. 2011). LRRTM1 is expressed during the
development of specific forebrain structures, and thus could influence neuronal
differentiation and connectivity. This is the first potential genetic influence on
human handedness to be identified, and the first putative genetic effect on
variability in human brain asymmetry (Francks et al. 2007). PCSK6 is known to
play a key role in regulating left-right axis specification, making it a highly
attractive candidate gene for involvement in handedness (Scerri et al. 2011).
There are several developmental factors in the womb and birth, including brain
damage resulting from stress during birth that can influence handedness. A surge
of fetal testosterone level during pregnancy can also influence handedness (Tran
et al. 2014). Environmental factors could also exert selection forces on lefthanders. Attitudes towards left-handedness vary from one culture to another.
Cultural and environmental factors could change hand preference (Llaurens et al.
2009).
Some suggest that the structure of the brain of sinistral (left-handed) and
dextral persons might differ, with a larger corpus callosum in those who are lefthanded (Coren 1995). One possible outcome of this exchange might be faster
access to a wider range of memories and associations. This would be of particular
advantage when the individual was engaged in divergent thinking, which moves
outward from conventional knowledge into unexplored association. Divergent
thinkers seem more capable of breaking sets and achieving novel solutions.
Divergent thinking usually produces "original" or "creative" ideas through the
breaking of typical thought sets, the reorganization of materials in uncommon
ways, and the consideration of a wide range of alternative solutions to complex
problems. For this reason divergent thinking is often listed as a major component
of the psychological trait of creativity. Certainly, divergent thinking would
facilitate performance in a number of areas where they appear to excel, such as
art, architecture, mathematics, chess, and so forth (Coren 1995).
2
Aim
The aim of this study is to determine frequency of left-handed people and
their creativity in Indonesia, particularly in Padang, West Sumatera.
MATERIALS AND METHOD
Time and Place
.
The research was held in February until April 2014 in Padang, West
Sumatera. Sampling was conducted in two Junior High School level and door to
door visits. Data was analyzed in Biosystematics and Ecology of Animals
Division, Department of Biology, Bogor Agricultural University.
Sample
The numbers of respondents in this research are 328 individuals consisted
of 126 males and 202 females in Padang, West Sumatera. The number of
respondents from two Junior High School level are 217 individuals. The number
of respondents from door to door visits are 111 individuals. Respondents are
Minangkabau ethnic group.
Collecting Personal Data
Respondents were asked personal information such as name, address,
gender, ethnic group, and recording of peigree of the respondents to determine
family mambers who are left-handed (Appendix 1).
Left-handed Preference
In determining left-handed preference, respondents were asked what hand
they prefer to use to throw a ball, use a spoon, saw, sew, shoot marbles, bowling,
or playing tennis, cut with a knife, cut with scissors, hammer, and write
(Appendix 2). If they routinely use the left hand or either hand for any number of
these 10 tasks, they are designated left-handed preference (Rife 1940).
Determination of Creativity
Adjective Check List (ACL) used to determine creativity of individual
respondents (Gough 1979). Respondents were given a questionnaire containing 30
adjectives and asked to cheklist adjectives that describe themselves (Appendix 3).
In the ACL, there are 30 adjectives that consists of 18 positive items and 12
negative items. In scoring ACL, 1 point given each time one of 18 positive items
is checked, and -1 point given each time one of 12 negative items is checked. The
3
theoretical range of scores is therefore -12 to +18. If respondents had a score ≤ 3
they are categorized as not creative, while a score of > 3 creative (Gough 1979).
RESULTS
Frequency of left-handed people
Percentage of hand prefer and frequency of handedness are shown in
Table 1. Highest percentage of prefer the left hand in males was hammer, while
in females was shoot marbles. Highest percentage prefer the both hands in males
and females were throw a ball. Total frequency of left-handed was 20%.
Frequency of left-handed males was 28% and frequency of left-handed females
was 15%.
Table 1. Percentage of hand prefer and frequency of handedness
Task
Males
Both
4% (5)
Right
83% (105)
6% (8)
2% (2)
92% (116)
Saw
12% (15)
1% (1)
87% (110)
Sew
12% (15)
2% (3)
86% (108)
Shoot
marbles
Bowling or
playing
tennis
Cut with a
knife
Cut with
scissors
Hammer
13% (16)
2% (2)
86% (108)
14% (17)
3% (4)
83% (105)
12% (15)
2% (2)
87% (109)
10% (13)
2% (2)
88% (111)
15% (19)
1% (1)
84% (106)
8% (10)
2% (2)
91% (114)
Throw a
ball
Use a spoon
Write
Frequency
of
handedness
Left
13% (16)
28% (35)
Total
72% (91)
100%
(126)
100%
(126)
100%
(126)
100%
(126)
100%
(126)
100%
(126)
100%
(126)
100%
(126)
100%
(126)
100%
(126)
100%
(126)
Left
8% (16)
Females
Both
2% (3)
Right
91% (183)
5% (10)
1% (2)
95% (190)
7% (15)
0% (0)
93% (187)
8% (16)
1% (1)
92% (185)
11% (23)
0% (0)
89% (179)
7% (15)
1% (1)
92% (186)
9% (18)
1% (1)
91% (183)
8% (16)
0% (0)
92% (186)
8% (17)
0% (0)
92% (185)
5% (11)
1% (1)
94% (190)
15% (31)
Total
85% (171)
( ) : the number of respondents
The respondents who conducted in Junior High School level and door to
door visits were 8-82 years old. The age range 8-18 were 260 individuals, 19-29
were 38 individuals, 30-40 were 13 individuals, 41-51 were 9 individuals, 52-62
were 4 individuals, 63-73 were 2 individuals and 78-84 were 2 individuals.
Percentage of prefer the left hand based on age are shown in Table 2. Highest
100%
(202)
100%
(202)
100%
(202)
100%
(202)
100%
(202)
100%
(202)
100%
(202)
100%
(202)
100%
(202)
100%
(202)
100%
(202)
4
percentage of prefer the left hand were age range 8-18 in all tasks. The age range
30-40, 63-73, and 74-84 were no one left-handed people.
Table 2. Percentage of prefer the left hand based on age
Task
Throw a ball
Use a spoon
Saw
Sew
Shoot marbles
Bowling or playing
tennis
Cut with a knife
Cut with scissors
Hammer
Write
8-18
79% (25)
77% (14)
77% (23)
81% (25)
76% (30)
82% (25)
Age (years)
19-29 41-51 52-62
9% (3)
9% (3)
3% (1)
6% (1) 11% (2) 6% (1)
10% (3) 10% (3) 3% (1)
10% (3) 6% (2)
3% (1)
13% (5) 8% (3)
3% (1)
9% (3)
6% (3)
3% (1)
100% (32)
100% (18)
100% (30)
100% (31)
100% (39)
100% (32)
79% (26)
83% (24)
78% (28)
76% (16)
9% (3)
7% (2)
11% (4)
19% (4)
100% (33)
100% (29)
100% (36)
100% (21)
9% (3)
7% (2)
8% (3)
5% (1)
3% (1)
3% (1)
2% (1)
0% (0)
Total
( ) : the number of respondents
Creativity
ACL scores ranged from -7 to +11. Percentages of creativity in
handedness are shown in Table 3. Percentage of creative right-handed people
(ACL >3) was 36% and percentage of creative left-handed people was 50%. The
creative right-handed males were 39% and creative right-handed females were
35%. The creative left-handed males were 66% and creative left-handed females
were 32%. The result of this research show that percentage of creative males and
females with right-handed preferences is not different , while for left-handed the
proportion of creative males is higher than of females.
Table 3. Percentage of creativity in handedness
Left-handed
Males
Creative Not creative
66% (23) 34% (12)
Right-handed
39% (35)
62% (56)
Total
Females
Creative Not creative
100% 32% (10) 68 (21)
(35)
100% 35% (60) 65% (111)
(91)
Total
100%
(31)
100%
(171)
( ) : the number of respondents
Percentage of the total scores of ACL are shown in Table 4. Highest
percentage of left-handed males on the total score + 4, while for left-handed
females on the total score + 2. Highest percentage of right-handed males on the
total score +2 and +4, while for right-handed females on the total score 0.
5
Table 4. Percentage of the total scores of ACL
Left handed
Total
Score
-7
-6
-5
-4
-3
-2
-1
0
+1
+2
+3
+4
+5
+6
+7
+8
+9
+10
+11
Total
Males
0% (0)
0% (0)
0% (0)
0% (0)
0% (0)
3% (1)
0% (0)
0% (0)
11% (4)
9% (3)
11% (4)
32% (11)
14% (5)
11% (4)
6% (2)
3% (1)
0% (0)
0% (0)
0% (0)
100% (35)
Right handed
Females
0% (0)
0% (0)
3% (1)
3% (1)
3% (1)
3% (1)
7% (2)
7% (2)
16% (5)
23% (7)
3% (1)
10% (3)
3% (1)
3% (1)
10% (3)
3% (1)
3% (1)
0% (0)
0% (0)
100% (31)
Males
1% (1)
1% (1)
0% (0)
2% (2)
1% (1)
3% (3)
12% (11)
5% (4)
11% (10)
15% (14)
10% (9)
15% (14)
12% (11)
7% (6)
5% (4)
0% (0)
0% (0)
0% (0)
0% (0)
100% (91)
Females
0% (0)
1% (1)
1% (1)
2% (3)
1% (1)
2% (4)
8% (15)
9% (16)
13% (22)
16% (28)
12% (20)
11% (18)
11% (19)
7% (13)
3% (7)
1% (1)
0% (0)
1% (1)
1% (1)
100% (171)
( ) : the number of respondents
DISCUSSION
Frequency of left-handed people in Padang, West Sumatera was 20%.
Frequency of left-handed males was 28% and frequency of left-handed females
was 15%. The results showed frequency of left-handed males higher than of
females. The cerebral lateralization theory of Geschwind-Galaburda (Tran et al.
2014) posits that high intrauterine levels of testosterone promote the development
of left-handedness because of differential effects of testosterone on brain
hemisphere maturation; specifically, left brain hemisphere maturation is delayed.
Male brains are exposed to substantially higher testosterone levels than female
brains during prenatal development; hence, a sex effect for handedness may be
expected. Testosterone-induced effects on brain lateralization thus likely take
place early during embryonic development (Tran et al. 2014).
Percentage of creative left-handed people were higher than of righthanded. The result of this research show that percentage of creative males and
females with right-handed preference is not different, while for left-handed
percentage of creative left-handed males is higher than of females. The results of
study showed that only in males does handedness interact with mental ability
lends some support to a possible testosterone link. Obviously, male fetuses are
more likely to be exposed to the higher levels of testosterone than female fetuses.
6
If a dose or effect relationship were involved, this would mean that males are apt
to have the greatest growth in the planum temporale or any other affected areas of
the brain. This means that any benefit derived from changes in the normal pattern
of neurological development would be expected to be more visible in males than
females (Coren 1995).
CONCLUSION
Frequency of left-handed males in Padang, West Sumatera was higher
than of females. Percentage of creative right-handed males and females is not
different, while for left-handed percentage of creative males is higher than of
females.
REFERENCES
Coren S.1995. Differences in divergent thinking as a function of handedness and
sex. The American Journal of Psychology. 108(3): 311-325
Faurie C, Schiefenhövel W, le Bomin S, Billiard S, Raymond M. 2005. Variation
in the frequency of left‐handedness in traditional societies. Current
Anthropology. 46: 142–147.
Francks C, Maegawa S, Lauren J, Abrahams Bs, Velayos-Baeza A, Medland SE,
Colella S, Groszer M, McAuley EZ, Caffrey TM et al. 2007. LRRTM1 on
chromosome 2p12 is a maternally suppressed gene that is
associatedpaternally with handedness and schizophrenia. Molecular
Psychiatry. 12:1129-1139.
Gough HG.1979. A creative personality scale for the Adjective Check List.
Journal of Personality and Social Psychology. 37(8):1398-1405.
Llaurens V, Raymond M, Faurie C.2009. Review Polymorphism of handedness in
humans. Phil.Trans. R. Soc B. 364 : 881-894.
Raymond M, Pontier D.2004. Is there geographical variation in human
handedness?. Laterality. 9(1):35–52.
Rife DC. 1940. Handedness, with special reference to twins. Genetics 25: 178186.
Scerri TS, Brandler WM, Paracchini S, Morris AP, Ring SM, Richardson AJ,
Talcott JB, Stein J, Monaco AP. 2011. PCSK6 is associated with
handedness in individuals with dyslexia. Human Molecular Genetics. 20(3):
608-614.
Tran SU, Stieger S, Voracek M. 2014. Latent variable analysis indicates that
seasonal anisotropy accounts for the higher prevalence of left-handedness in
men. Cortex. 57 :188-197.
7
APPENDIX
8
Appendix 1 Research questionnaire
KUISIONER PENELITIAN
FNUM :
Tanggal
:
Data Pribadi
Nama Lengkap
Jenis Kelamin
Alamat
Suku (Minangkabau)
Kidal
Tempat / Tanggal Lahir
Usia
:
:P/L
:
:
: ya / tidak
:
:
Data Orang Tua
Nama Ayah
Asal
Suku (Minangkabau)
:
:
:
Nama ibu
:
Asal
:
Suku (Minangkabau) :
Nama Ayah dari Ayah
Asal
Suku (Minangkabau)
:
:
:
Nama Ayah dari Ibu :
Asal
:
Suku (Minangkabau) :
Nama Ibu dari Ayah
Asal
Suku (Minangkabau)
:
:
:
Nama Ibu dari Ibu
Asal
Suku (Minangkabau)
Pedigree (silsilah)
:
:
:
9
Appendix 2 Handedness questionnaire
Ceklis ( √ ) tangan mana yang nyaman dan biasa anda gunakan dalam melakukan
kegiatan berikut :
No
Kegiatan
Tangan yang digunakan
Kiri
1
Melempar
2
Bermain bowling / tenis /
bulutangkis
3
Bermain kelereng
4
Memotong dengan pisau
5
Makan dengan sendok
6
Memalu
7
Menggerggaji
8
Menjahit
9
Menulis
10
Menggunting
Kanan
10
Appendix 3 Creativity determination
Ceklis ( √ ) semua sifat dibawah ini yang anda anggap mendeskripsikan diri anda.
___mampu
___jujur
___mudah terpengaruh
___cerdas
___pintar
___sopan
___berhati-hati
___ketertarikan luas
___yakin
___berdaya cipta
___egois
___asli, tidak mencontoh
___lumrah
___ketertarikan sempit
___suka bercanda
___berpikir panjang
___tradisional
___tulus
___tak-bergantung ke orang lain
___banyak akal
___biasa, menurut adat
___percaya diri
___tidak resmi
___sexy
___tidak berpuas-diri
___patuh
___berwawasan
___tinggi hati
___curiga
___tidak biasa, diluar peraturan
Positive and negative items on ACL
Positive
mampu
pintar
yakin
egois
suka bercanda
tak-bergantung ke orang lain
tidak resmi
berwawasan
cerdas
ketertarikan luas
berdaya cipta
asli, tidak mencontoh
berpikir panjang
banyak akal
percaya diri
sexy
tinggi hati
tidak biasa, diluar peraturan
Negative
mudah terpengaruh
berhati-hati
lumrah
tradisional
biasa, meurut adat
tidak berpuas-diri
jujur
ketertarikan sempit
sopan
tulus
patuh
curiga
11
RIWAYAT HIDUP
Penulis lahir di Padang pada tanggal 14 Mei 1992 dari pasangan Ir Sjafri.S
dan Salwati sebagai anak ketiga dari tiga bersaudara. Penulis menyelesaikan
pendidikan di SMA Negeri 2 Padang pada tahun 2010 dan melanjutkan studi pada
Jurusan Biologi, Fakultas Matematika dan Ilmu Pengetahuan Alam, Institut
Pertanian Bogor melalui jalur SNMPTN. Selama mengikuti perkuliahan, penulis
aktif sebagai anggota di Divisi Pamabi (Paguyuban Mahasiswa Biologi)
Himpunan Mahasiswa Biologi (Himabio) IPB pada periode 2011/2012 dan
2012/2013.
Penulis melakukan Studi Lapangan pada tahun 2012 dengan judul
penelitian Keanekaragaman Gymnospermae di Kebun Raya Cibodas. Penulis
melakukan Praktik Lapangan pada tahun 2013 dengan judul Identifikasi Jabon
(Anthocephalus cadamba) dan Nyamplung (Calophyllum inophyllum) sebagai
Sumber Daya Genetik di Unit Pelaksana Teknis Daerah Perbenihan Tanaman
Hutan
Dinas
Kehutanan
Provinsi
Sumatera
Barat,
Padang.