Birth order & intelligence

Birth order and intelligence 1

CHAPTER I

INTRODUCTION

Does our birth order really affect intelligence? Much research has been revolving around

this question. This issue has once again risen in popularity in the recent years. Debates on the

relationship between birth order and intelligence are surrounded by ambiguity and controversies.

There are countless reports of argument regarding this issue. Some believe that the older

sibling has the upper hand (Kristensen & Bjerkedal, 2007); where else others deem the youngest

to be brighter (Carey, 2007). Yet, others have found no relationship between birth order and

intelligence (MacCallum et. al., 2007).

As this study has yet to be conducted in Malaysia, curiosity regarding the pattern of birth

order and intelligence has arose. Due to the different cultural background of previous research,

the results from abroad may not be applicable to the Malaysian context.

The influence of the Asian and Western culture may cause deviations on the basis of

intelligence (Arthur, n. s.). This is supported by a research saying that Asians, when compared to

Westerners, are able to obtain 5 to 10 points higher than the Caucasians and African Americans

(Arthur, n. s.). There are also different perspectives in defining the roots of intelligence, where

Westerners believe that intelligence is an in-born trait, contrasting to the Asians who consider

intelligence as a result of hard work (Arthur, n. s.).

Literature Review

Birth order. Have you ever looked at another sibling and thought what it would be like

if we were them? Why is it that they differ so much from us? Would life be different for us? The

probability is uncertain and it is difficult for us to determine. Birth order is one of the many


things that affect the way we carry ourselves and how we interact with our surroundings (Leman,

2005).

Birth order is the rank or order of a person by age among his or her siblings (Reber &

Reber, 2001). It refers to the position in which we are placed in our family whereby we could be

the first child, middle child or even the youngest child (Leman, 1985).

Several research think that the way we mature is highly influenced by where we are in a

relationship with our siblings (Leman, 1985). According to Leman (1985), birth order is a way in

which we can acquire some clues as to why we are the way we are, although it may not

accurately predict how a person would turn out. To sum up Leman’s (1985) points, he said that a

person’s order of birth has a lifelong effect on whom and what a person turns out to be.

A columnist, Brockenbrough (2007), states that birth order is the idea that our position in

the family has influence on which who we are – composing of our personality traits to the overall

intelligence. Some people give credit to birth order as they did to astrology, leading to sibling

rivalry (Brockenbrough, 2007).

How do people remember their birth order? A scientific study done on the fruit fly,

drosophila, can illustrate the resemblance to the functioning of the human brain. In this research,

it is found that the brain cells function in a sequence of transcribing feature activation allowing

the neuroblasts to give rise to a series of different daughter cells (Doe, 2001). Initially, this brain

patterns were found in the fruit fly, drosophila. The daughter cells then ultimately become

neurons and glial cells in the brain (Doe, 2001).

Scientists have also found that the daughter cells carry on producing the particular

transcription factor that was active in the neuroblast at the time of birth (Doe, 2001). It is a

memory that allows neurons to maintain differences based on their time of birth (Doe, 2001). As


an example, the first-born drosophila neurons usually make the longest axon projections to

remote targets as compared to later-born drosophila that usually makes a shorter axon projection.

This connection between the brain functioning of the fruit fly and the human brain is hypotheses

to be rather similar.

Alfred Adler (1870 – 1937), an Austrian psychiatrist who was the pioneer researcher of

birth order, proposed that the chronological order of siblings at birth or their position in the

family has a substantial influence on the child’s development as well as personality (Stein, n.s.).

He was the first theorist to include not only both the child’s parents and surrounding adults, but

also the child’s brothers and sisters (Boeree, 2006). From the Adlerian point of view, birth order

is merely one of five major influences on personality development.

Besides birth order, it also includes physical structure and appearance, shaping education,

social and economic status and gender roles (Stein, n.s.). Adler’s theory of birth order is

considered one of the useful theories that contribute to the understanding of the order of birth but

at the same time, it should not be taken too seriously (Boeree, 2006).

Results of past research on birth order vary from one another, therefore making it a

controversial subject which is still all together interesting. Based on the initial research done by

Adler, birth order has been linked to various situations by present-day experts and analysts. The

personality aspect is widely researched on compared to the other portions such as intelligence,

career choice, sexual orientation and also cancer risk (Needlman, 2001). Examining the family

structure carefully is crucial as the birth order can reveal many things in a child (Needlman,

2001). With the many factors that influence the birth order, this study solely focuses on how

intelligence is linked to the birth order.


Intelligence. Intelligence is an abstract word which is much easier described than

defined. It is often referring to other’s intelligence by unfolding people as smart, sharp, bright,

brilliant and many more (Baron & Kalsher, 2002). The American Psychological Association

(APA) has defined intelligence as the “ability to understand complex ideas, to adapt effectively

to the environment, to learn from experience, to engage in various forms of reasoning, and to

overcome obstacles by taking thought” (Wood, Wood & Boyd, 2004).

The ability to learn about, learn from, understand, and interact with one’s environment is

termed as intelligence (Bainbridge, 2007). This ability includes a number of specific abilities

such as adaptability to a new environment, capacity for knowledge and the ability to acquire it,

capacity for reasoning and abstract thinking, skill to grasp relationships, aptitude in evaluating

and judging and the capacity for productive thinking (Bainbridge, 2007). All these abilities and

more, mainly circles around the abilities of a person to learn and interrelate with the environment

(Bainbridge, 2007).

Charles Spearman, in the early 20th century, proposed the existence of general

intelligence, observed that people’s scores on different IQ tests tends to correlate. Therefore, he

concluded that all IQ tests measures the same factor which is the general-factor (Roulinski,

2007). The general-factor includes all logical tasks and mental capacities (Sternberg, 2006).

Apart from that, a similar theory by R. Cattell and J. Horn, argues that there are two types of

intelligence which is the fluid and crystallized intelligence (Roulinski, 2007). Fluid intelligence

is the biological ability to reason and acquire new information as compared to the crystallized

intelligence which is learned through experience and exposure (Roulinski, 2007).

Some theorists proposed that there are different types of intelligence instead of

unearthing the essentials of intelligence. Robert Sternberg’s triarchic theory of intelligence is


more widely known, than the theory of multiple intelligence proposed by Gardner (Wood, Wood

& Boyd, 2004).

Sternberg’s theory as its name implies, consists of three separate, though interrelated

abilities, namely analytical intelligence, creative intelligence and practical intelligence (Wilson,

2005). The first capacity, analytical or componential intelligence, is referred more as the

traditional conception of intelligence, whereby it looks mostly into abstract thought and

reasoning as well as verbal and mathematical skills (Huitt, 1999). Individuals who have

analytical intelligence are basically high achievers in class (Hetherington E. M., Parke R. D.,

Gauvain M. & Locke V. O., 2006)

Next, would be the experiential or creative intelligence, which is characterized by an

individuals’ ability to generate new ideas, handle unique situations and also to think innovatively

(Huitt, 1999). The final capability proposed by Sternberg is the contextual or practical

intelligence (Huitt, 1999). This refers to the street smart individuals that have the ability to apply

their knowledge in the real world situation (Huitt, 1999).

In the multiple intelligence approach as proposed by Gardner, there are nine types of

intelligence which are the naturalist, musical, logical-mathematical, existential, interpersonal,

bodily-kinesthetic, linguistic, intra-personal and spatial intelligence (Gardner, n.s). The naturalist

intelligence or nature smarts are able to discriminate among living things as well as are sensitive

to other features of the world (Gardner, n.s).

As for the musical intelligence, it enables us to distinguish, craft, reproduce, and reflect

on music. Mathematical and musical intelligences may share the common cognitive processes.

People with logical-mathematical intelligence have the ability to calculate, compute, use abstract

symbolic thought, sequential reasoning skills and carry out complete mathematical operations


(Gardner, n.s). Next, is the existential intelligence where these people have the sensitivity and

capability to tackle mysterious questions about human existence (Gardner, n.s).

Interpersonal intelligence or better known as people smart, are capable of understanding

and interacting effectively with others. As for the ability to maneuver objects and use a variety of

physical skills with good body-mind coordination is referred to as the bodily-kinesthetic

intelligence (Gardner, n.s). Besides that, the linguistic intelligence is the talent to think in words

and express complex meanings using language (Gardner, n.s).

Intra-personal intelligence on the other hand, is the capability to understand oneself and

one’s thoughts and feelings, and using that knowledge in determining and planning the direction

of their lives (Gardner, n.s). Lastly, the spatial intelligence is the ability to think in three

dimensional forms, where it involves mental imagery, graphic and artistic skills and an active

imagination (Gardner, n.s).

There are a few ways of measuring intelligence. Psychometric approach are based on

how well people perform on standardize aptitude tests. These tests are used to measure skills and

knowledge gathered (Wade & Tavris, 2002). The psychometric test that is extensively used in

measuring intelligence is the Stanford-Binet Intelligence test which was devised in 1904 (Wade

& Tavris, 2002). Later on, others developed a scoring system by using the child’s mental age

divided by the child’s chronological age. This results in the intelligence quotient, also known as

IQ (Baron & Kalsher, 2002). IQ is attained by using the mental age divided by the chronological

age, then multiplied by 100 (Baron & Kalsher, 2002).

From these psychometric tests, many researchers regarding intelligence have been able to

use these measurements as a comparison and guide point. Intelligence has been involved in

research on several areas such as birth order, brain functioning and lots more.


Birth order and intelligence. This research has yielded contradicting results whereby

some state that the birth order affects a person’s intelligence as well as the other extreme of no

such overlap between intelligence and birth order. Rodgers, Cleveland, Van den Oord, and Rowe

(2000) believe that the connection between intelligence and birth order is merely a

“methodological illusion” due to the variation in results from the different methods used (Evans

& McClintic, 2002).

Zojonc (2001) who believes that birth order does impact a person’s intelligence

developed the confluence model. This model shows that each successive sibling is born into a

weaker intellectual surrounding and that intellectual accomplishment is amplified as family size

decreases (Evans & McClintic, 2002). But the studies only show a tiny advantage in first-born -

about one IQ point higher than the second sibling, two points higher than the third sibling, and so

on. These minor differences are not likely to matter in the quest of distinction (Sulloway, 1996).

The outcomes differ from each other as in the study done by Steckel (1930), where he

concluded that the average intelligence of later-born children was higher than the older children

and that intelligence increases with the ordinal number of a family (Walton, 2001). This is

because parents tend to prefer last-born children, thus, increasing the time spent together and

leading to enhancing intelligence (Walton, 2001).

Opposing this idea was the study completed by Burton (1967) stating that oldest siblings

tend to have higher intelligence than younger siblings (Walton, 2001).

Apart from that, a recent study has shown that birth order does not have any effects on

intelligence. Wichman A. (2006), stated that, “Birth order may appear to be associated with

intelligence, but that's only because larger families don't have the advantages of smaller families.

When examined within families, there is no evidence of any significant association between birth


order and intelligence. Birth order is not all that important compared to family environment and

genetic influences (ScienceDaily, 2007). He pointed out that the mother’s age at the birth of the

first child plays a great role in determining the expected intelligence scores (Wichman, 2006).

The younger a mother was at the delivery of her first infant, the lower the intelligence scores are

projected to be within a family (Wichman, 2006).

Why it is that birth order might affect intelligence? As the first-born, they would be more

likely to have financial resources to continue education, being treated as a companion by parents

(therefore, having more responsibility) and would get significantly more attention and

nourishment compared to the following siblings (Galton, 1874).

Apart from that, first-born and only-born children also tend to attribute others’ work

accomplishment to the internal locus of control. This gives them the extra strive for higher

achievement as compared to later-born (Phillips and Phillips, 1994 as cited by Guastello &

Guastello, 2002).

As topic is still in the heat of debate, many more research would be conducted to further

studies on the relationship of birth order and intelligence as the topic has not found its stand.

Therefore, the debate on this topic would promise more new findings in the future.

Statement of Problem

The findings of previous research have found the older sibling to be comparatively

smarter than younger siblings. Based on these findings, families often treat the firstborn as an

academically smart individual, and the younger siblings merely fulfil the other roles: the rowdy

one, the flirt and other niches that are usually unconstructive (Carey, 2007). Due to this problem,

it is hypothesized that many people label others based on their predicted intelligence, especially

parents labeling their children based on their birth order.


This situation especially limits the growth of the younger siblings as parents would tend

to undermine their abilities and intellectual abilities. The birth order may somehow affect a

person’s intelligence but it should not be the basis of judging one’s intelligence.

Some on the other hand, are not aware of the capabilities and limitations of a particular

child. This situation would be stressful to children who are urged to perform beyond their

capabilities. Therefore, it would not be wise to either judge or overestimate a child’s capabilities.

Target Group

Due to the basis of this study on birth order and intelligence, it would hold great

significance as it would be of a certain interest to nearly everyone in Malaysia. The group of

people that would be particularly interested in this study would be researchers, educators, parents

and the children themselves.

Research Objectives

The main objective of this research is to explore the relationship between birth order and

intelligence in Malaysian children. Is there any significant pattern between the two in the context

of the Malaysian society? Does the birth order affect intelligence in the context of Malaysian

culture?

Significance of Study

The outcome of this study would be helpful to educators as well as parents, to understand

the strong points along with the limitations of a child in performing a certain task. By knowing

these limitations, the child would not be strained to follow the footsteps and match or better the

achievement of the more successful siblings. This study should not be used as a basis of judging

one’s abilities as each person has the potential for growth and improvising themselves. An


individual should not be contained within a certain label and also submit to the conditions that

comes together with the label.

Research Question

The research is designed to address the research question of “Is there any significant

relationship between birth order and intelligence in Malaysian children?”. This question

illuminates the connection between birth order and intelligence in the context of Malaysian

children.

Hypothesis

A research hypothesis formed would be that there is a significant relationship between

the birth order and intelligence. To specify the hypothesis a little more, an assumption that the

younger sibling would illustrate a higher level of intelligence as compared to the older sibling.

Alternate Hypothesis. There is a significant positive relationship between birth order and

intelligence in Malaysian children.

Null Hypothesis. There is no significant relationship between birth order and

intelligence in Malaysian children.


CHAPTER II

METHODOLOGY

The data collection design used in this study is the quantitative research method, where

the numerical data or anything that is quantifiable is collected and analyzed to provide suitable

explanations (Hopkins, 2000). The method uses statistical summaries to present the obtained

results.

This study is also a cross-sectional research design, as all the participants will only be

assessed once to have the relationship between the variables determined (Hopkins, 2000). A

cross-sectional study is quick and can be used to examine a large number of sample with little

cost and effort.

Participants

The study population addresses children in all states of Malaysia. As for the sample

population, a part of the population being examined, 65 participants consisting of 20 males and

45 females, aged between 10 and 11 years old, in the area of Klang Valley are chosen. The

samples were selected based on a non probability sampling or convenience sampling (see Table

2.1, pg 12).

Place

The study was conducted in a designated empty classroom at Sekolah Kebangsaan

Taman Desa situated in Taman Desa, Kuala Lumpur. The location was chosen to the

convenience of the participants, school administrator and researcher.


Table 2.1:

Summary of participants’ sampling

Birth Order Gender Age10 years 11 years

First-born / Only child

Male 2 4Female 8 9

Middle-born Male 5 1Female 7 3

Last-born Male 6 2Female 9 9

TOTAL 65

Measurement Tools

Kaufman Brief Intelligence Scale, 2nd Edition (KBIT2). KBIT2 is administered to assess

the participants IQ in addition to a demographic data. The demographic data includes gender,

age, birth date, race, position in family (birth order), number of siblings and the main language

spoken at home.

The questions are designed to measure a person’s verbal and nonverbal cognitive ability.

The verbal score comprises of two subsets (verbal knowledge and riddles) and it measures

verbal, word knowledge, general information, verbal concept formation and reasoning. As for the

non verbal score (matrices subset), it calculates the ability to solve new problems by recognizing

relationships and the entire visual analogy (Kaufman & Kaufman, 2004).

From a hypothetical standpoint, the verbal division computes crystallized ability where

else the non verbal division assess the fluid reasoning (Kaufman & Kaufman, 2004).

Equipments. Apparatus used in the process includes a pen to answer the questionnaire as

well as to jot down the scores obtained; a calculator to work out to IQ scores of the participants;

and finally a computer to key in and analyze the data gained.


Computer Software. The computer software utilized is the Windows XP Home Edition.

Apart from that, Microsoft Word is used to generate the written report of the research. Also, a

statistical program, Statistical Package for Social Science (SPSS) 12.0 for Windows, is used to

analyze the figures gained from the questionnaires collected.

Procedure

A suitable school in the Klang Valley was chosen. The headmistress of the specific

school was contacted and briefed regarding the research. A letter was prepared under the name of

Universiti Tunku Abdul Rahman (UTAR) to acquire consent. A consent form was signed by the

school’s headmistress after agreeing to the conditions of the research. The teacher in charge then

selected 60 participants from the school’s 10 and 11 year olds that meet the requirements.

The test was administered on two different days (15 and 16 January 2008), by conducting

the test with one age group per day. The participants were placed in a classroom on the specified

date and instructions were given when the participants were seated. 40 to 45 minutes was given

to the participants to complete the intelligence test. All completed questionnaires were then

returned to the researcher. Test scores are calculated and analyzed using the SPSS program.

Reliability and Validity

Intelligence Quotient (IQ). IQ is now recognized as a reliable source to measure and

quantify the intelligence of a person (Baron & Kalsher, 2002). IQ scores are also highly

predictive of real-world outcomes (academic performance, performance on the job, general

adjustment and health) (Hetherington, Parke, Gauvain & Locke, 2006).

Kaufman Brief Intelligence Test, 2nd Edition (KBIT2). According to Kaufman and

Kaufman (2004), the test has high internal-consistency reliability between the subsets ranging


from 0.86 to 0.88. The reliability of the IQ composite is excellent by reporting a reliability

coefficient of 0.93 among children ages 10 to 18.

As for its validity, KBIT2 takes in to account the age variable that leads to the increasing

and decreasing of raw scores. A table portraying the means and standard deviation of raw scores

for each age group is presented. The results across the age range of 4 to 90 presents a strong

foundation for the construct validity (Kaufman & Kaufman, 2004).

Data Analysis

The data gained in the test are compiled and calculated. Statistical analysis was managed

using the SPSS program. Based on the calculated data, the samples are recoded into three birth

order groups, which are first-born and only child, middle-born and last-born. The Pearson

correlation was also administered to examine the relationship between birth order and IQ.

Gender and birth order was also selected in further analysis.


CHAPTER III

RESULTS

Descriptive statistics

From the tabulated data, it is shown that from the 65 samples obtained, 30.8% consists of

males and 69.2% of females. As for the age range, there is 56.9% of 10 year olds and 43.1% 11

year olds. The sample is made up of 44.6% of Chinese, followed by 30.8% Malays, 21.5% of

Indians and 3.1% of other races (Punjabi). The main language spoken at home is divided into

two languages which are Bahasa Melayu (21.5%) and English (78.5%). From the sample, there is

40.0% of last-born, 32.3% of first-born, 24.6% of middle-born and only 3.1% as the only child.

From the total samples of first-born and only child, 10 individuals scored average IQ

composite, 11 scoring above average and only 2 in to the upper extreme. As for middle born, 11

attained average IQ composite scores, where else 3 with above average and 2 in upper extreme.

Finally, 9 last-born scored on the average level, while 14 achieving above average and 3 with

upper extreme IQ composite (see Figure 3.1, pg 15).

Figure 3.1: Distribution of IQ composite and birth order


Further detailed distribution of IQ composite scores (verbal knowledge and non verbal

knowledge) between birth order is shown (see Table 3.1, pg 16).

Table 3.1:

Distribution of IQ range and birth order

Birth Order IQ Range Verbal Knowledge

Non Verbal Knowledge

IQ Composite

First-born and Only child

Below Average - - -

Average 9 13 10

Above Average 9 9 11

Upper Extreme 5 1 2

Middle-born Below Average 2 - -

Average 9 10 11

Above Average 1 6 3

Upper Extreme 4 - 2

Last-born Below Average 2 - -

Average 6 19 9

Above Average 15 6 14

Upper Extreme 3 1 3

TOTAL 65 65 65


Hypothesis: There is a significant relationship between birth order (position in family) and IQ

The result of Pearson’s correlation showed that there is no significant relationship

between the birth order with IQ composite, r (65) = 0.109, n.s. As subsets of the IQ composite,

the verbal knowledge, r (65) = 0.161, n.s., and non verbal knowledge, r (65) = 0.049, n.s., also

revealed non significant results (see Table 3.2, pg 17). Therefore, the null hypothesis is being

accepted.

Table 3.2:

Correlation – Birth order and IQ composite

Birth Order IQ Composite

Verbal Knowledge


Birth Order Pearson Correlation

1 -.105 -.171 -.085

P-Value . .407 .174 .502

IQ Composite

Pearson Correlation

-.105 1 .795** .416**

P-Value .407 . .000 .001

Verbal Knowledge

Pearson Correlation

-.171 .795** 1 .224

P-Value .174 .000 . .072


Pearson Correlation

-.085 .416** .224 1

P-Value .502 .001 .072 .

**. Correlation is significant at the 0.01 level (2-tailed)


Since there is no significant relationship between birth order and IQ, further examination

shows that the result of the Pearson’s correlation showed that there is a positive significant

correlation between the verbal knowledge and IQ composite in the first-born and only child, r

(23) = 0.777, p<0.01 (see Table 3.3, pg 18). This illustrates that first-born are better in verbal

knowledge.

Table 3.3:

Correlation – Relationship between first born and only child with IQ

IQ Composite Verbal Knowledge


IQ Composite Pearson Correlation

1 .777** .335

P-Value . .000 .119Verbal

KnowledgePearson

Correlation.777** 1 .090

P-Value .000 . .683Non Verbal Knowledge

Pearson Correlation

.335 .090 1

P-Value .119 .683 .**. Correlation is significant at the 0.01 level (2-tailed).


It is shown from the result of the Pearson’s correlation that there is also a positive

significant correlation between the verbal knowledge and IQ composite in middle-born, r (16) =

0.884, p<0.01 (see Table 3.4, pg 19). Thus, middle born is also good in verbal knowledge.

Table 3.4:

Correlation - Relationship between middle-born with IQ




1 .884** .252


KnowledgePearson

Correlation.884** 1 -.081


Pearson Correlation

.252 -.081 1



As for the last-born, the result of the Pearson’s correlation shows that there is a positive

significant relationship between both verbal knowledge, r (26) = 0.741, p<0.01 and non verbal

knowledge, r (26) = 0.654, p<0.01, with IQ composite (see Table 3.5, pg 20). It is deduced that

last-born is good in both verbal and non verbal knowledge.

Table 3.5:

Correlation - Relationship between last-born with IQ




1 .741** .654**


KnowledgePearson

Correlation.741** 1 .576**


Pearson Correlation

.654** .576** 1



After seeing that there are differences in the relationship between birth order and the

subsets of IQ, the research is further refined to include gender as a variable.

Firstly, for first-born and only child, the result of the Pearson’s correlation shows that

there is no significant relationship between verbal knowledge and IQ composite, r (6) = 0.707,

n.s., and also non verbal and IQ composite, r (6) = 0.316, n.s., in males (see Table 3.6, pg 21).

There is no credible connection between birth order and IQ as the sample consists of only 6

participants.

Table 3.6:

Correlation - Relationship between first-born and only child males with IQ




1 .707 .316


KnowledgePearson

Correlation.707 1 -.447


Pearson Correlation

.316 -.447 1



On the other hand, the result of the Pearson’s correlation shows that there is a significant

correlation between verbal knowledge and IQ composite in female first-born and only child, r

(17) = 0.823, p<0.01 (see Table 3.7, pg 22). This implies that female first-born and only child

are decent in the acquirement of verbal knowledge.

Table 3.7:

Correlation - Relationship between first-born and only child females with IQ




1 .823** .364


KnowledgePearson



Pearson Correlation

..364 .072 1



The result of the Pearson’s correlation shows that there is a significant correlation

between both verbal knowledge and non verbal knowledge with IQ composite in middle-born

males, r (6) = 1.000, p<0.01 (see Table 3.8, pg 23). Middle-born males are shown to be

respectable in getting hold of both the verbal and non verbal knowledge.

Table 3.8:

Correlation - Relationship between middle-born males with IQ




1 1.000** 1.000**

P-Value . . .Verbal

KnowledgePearson

Correlation1.000** 1 1.000**

P-Value . . .Non Verbal Knowledge

Pearson Correlation

1.000** 1.000** 1

P-Value . . .**. Correlation is significant at the 0.01 level (2-tailed).


Moving on, the result of the Pearson’s correlation shows that there is a significant

positive relationship between verbal knowledge and IQ composite, r (10) = 0.890, p<0.01, but no

significant correlation is shown between non verbal knowledge and IQ composite in middle-born

females, r (10) = 0.111, n.s. (see Table 3.9, pg 24). This means that middle-born females are

excellent in the attainment of verbal knowledge but lack the sparkle in terms of non verbal

knowledge.

Table 3.9:

Correlation - Relationship between middle-born females with IQ




1 .890** -.535


KnowledgePearson

Correlation.890** 1 -.650*


Pearson Correlation

-.535 -.650* 1

P-Value .111 .042 .*. Correlation is significant at the 0.05 level (2-tailed).

**. Correlation is significant at the 0.01 level (2-tailed).


In deeper analysis of last-born, the result of the Pearson’s correlation shows that there is a

significant positive relationship between verbal knowledge and IQ composite, r (8) = 0.908,

p<0.01, and non verbal with IQ composite, r (8) = 0.777, p<0.05, in males (see Table 3.10, pg

25). The last-born males are revealed to have better comprehension of both verbal and non verbal

knowledge.

Table 3.10:

Correlation - Relationship between last-born males with IQ




1 .908** .777*


KnowledgePearson

Correlation.908** 1 .747*


Pearson Correlation

.777* .747* 1




In last-born females, the result of the Pearson’s correlation also shows that there is a

significant relationship between both verbal knowledge with IQ composite, r (18) = 0.616,

p<0.01, and non verbal with IQ composite, r (8) = 0.531, p<0.05 (see Table 3.11, pg 26). Last-

born females are also equally as proficient as last-born males in the acquisition of verbal and non

verbal knowledge.

Table 3.11:

Correlation - Relationship between last-born females with IQ




1 616** .531*


KnowledgePearson



Pearson Correlation

.531* .417* 1




CHAPTER IV

DISCUSSION

Birth Order and Intelligence

Referring back to the results of the study, it was found that there is no significant

relationship between birth order and intelligence in Malaysian children. Thus, it can be

concluded that a child’s intelligence is not affected by his or her position in a family (birth

order). The result of the study supports the idea of Rodgers et. al. (2000) that the linkage between

birth order and intelligence is purely a mechanical delusion.

The available research that supports the findings is done in direct comparison between IQ

scores of siblings in the same family. In a relatively recent research, Wichman (2006) has

concluded that there is no relationship between birth order and intelligence. Rodgers and

colleagues (2000) attributed that there is no birth order effect on IQ as direct comparison of

siblings within the same family removes the possibility of any confounding variables such as

family size (Harris, 2001). This research also dates back to 1973, where there was a reported

negative association between birth order and intelligence in young Dutch men (Kristensen &

Bjerkedal, 2007).

From the many research done, several conclude that there is a connection between the

two variables. Then again, based on an argument by Wichman, Rodgers and MacCallum (2007),

these differences are due to the fact that data is collected based on the cross-sectional design and

also samples taken from between families and not intra-familial (Sayfer, 2007). Comparatively,

the results obtained from the study of Malaysian children shows that IQ nonetheless does not

affect birth order in children despite the samples being from different families and also the use of

cross sectional research design.


Results of the study also showed that there is a significant relationship between verbal

knowledge and IQ composite in first-born, only-born and middle-born children. But in the case

of the last-born, there is a significant relationship between both verbal knowledge and non verbal

knowledge with IQ composite. In other words, there is a connection between the position in the

family and the ability of acquiring of knowledge. First-born, only-born and middle-born children

are seen to be related to the acquisition of verbal knowledge where else last-born children are

associated to both. How do we explain this scenario?

By being the first-born or only child, they are given the fullest of attention and discipline

by their parents (Clayton, 1998). Parents also tend to be more restrictive, overly anxious and

have high expectations towards the child, thus exposing them to more adult thinking (Walton,

2001). With the strict supervision of parents, it guides the first-born and only-born to go hand-in-

hand with the reflected dreams of each parent (Child Development Institute, 2007). The

undivided attention given as infants provides the first-born and only-born children with

additional cumulative adult attention, which leads to enrichment of vocabulary and reasoning

(Carey, 2007). Owing to this situation, first-born and only-born children tend to be high

achievers, in a sense, good with verbal knowledge (Hetherington, Parke, Gauvain, Locke, 2006).

The fact that first-born children have to fulfill the role as a tutor to younger siblings has

also benefited the child (Carey, 2007). When a younger sibling proposes a question, it triggers

the tutor to think intensively making them gain an intellectual advantage (Evans & McClintic,

2002).

Another reasoning to why first-born and only-born are better in verbal knowledge is that

they have high “need for achievement” (nAch) (Falbo & Polit, 1986 as cited by Wood, Wood &

Boyd, 2004). As nAch mostly focuses on gaining accomplishments, for a child, the best triumph


would be in the academic achievements. In Malaysia, the academic system is focused more on

the verbal, word knowledge, concept formation and reasoning rather than creative thinking.

Consequently, first-born and only-born tend to be high achievers in schools.

It would be more difficult to explain the relationship between verbal knowledge and IQ

composite in middle born as not many research has been done on this group. Middle-born

children are required to share parental resources with either the older or younger sibling

(Hertwig, Davis, & Sulloway, 2001 as cited by Sulloway, n.s.). With this, they are more

independent in all aspects in order to be able to compete with the other siblings (especially the

older sibling) for parental attention (Sulloway, n.s.). In order to compete with the older sibling,

the middle-born needs to improve and be independent in acquiring knowledge, mostly verbal

knowledge (Rimm, 2002).

From reasoning, although tutoring is not dominant in middle-born children, they too

share the opportunity to guide and mentor the younger siblings, which in turns provides the

similar effects for the middle-born children (Carey, 2007).

Why does the IQ composite of last-born children have a relationship with both verbal and

non verbal knowledge? Normally, the youngest child would be favored more by the parents,

which would very much develop the child’s intelligence. This is due to the increasing contact

hours spent with the parents (Steckel, 1930 as cited by Walton, 2001). It is shown that the

average intelligence of later-born children was superior to those of earlier-born children (Walton,

2001). Even if last-born children have better verbal knowledge, how does non verbal knowledge

come in to place?

Parents control over their children decrease with birth order. They may be entirely strict

with the first-born but for the last-born, they can be extremely lenient (Walton, 2001). Last-born


children are also given less responsibilities which enable them to spend more time exploring the

surroundings. Due to the extrovert nature of last-born children, they are more exploratory and

creative (Sulloway, n.s.), and this presents the last-born children the upper hand in non verbal

knowledge (resolving new problems and identifying relationships).

For first-born, only-child and middle-born children, the main source of social learning is

entirely focused on the parent itself where else the last-born children are able to refer to both

parents and older siblings as models and teachers (Dunn, 1993 as cited in Hetherington, Parke,

Gauvain, Locke, 2006). This gives them the advantage to gain more information as compared to

the other birth order groups.

As for the detailed analysis of gender and the components of intelligence, there is no

significant relationship between gender and intelligence. Findings from male and female

respondents have only a slight variation. This is supported by a research stating that sex has

diminutive or no effect on IQ scores (Carey, 2007).

Also according to the Oxford University Press (2000), men and women have similar

average scores on various tests of intelligence. Kaufman and Kaufman (2004) also take in to

account the gender variable in devising an intelligence test, whereby affirming that there is very

minute sex differences in intelligence.

Limitations and Recommendations of Study

The study is conducted to look at the relationship between birth order and intelligence of

children in Malaysia. There are several limitations that are unavoidable. One of it would be the

sample size. The participants were only selected from a particular school in the Klang Valley and

also a specified age. It would be hard to generalize the sample to the whole of Klang Valley,

what more Malaysia. Therefore, if the issue is to be further researched on, a larger sample size


that includes obtaining a more distributed sample throughout the states in Malaysia would help in

terms of the reliability and accuracy of findings.

Apart from that, the applicability of KBIT2 also showed some cultural influence. A small

part of the questions in KBIT2 is beyond the knowledge range of Asians, as well as the inclusion

of culture sensitive pictures. The pictures were either removed or replaced based on the context

of the question. For further research purposes, a more suitable test should be founded or

modification of the original test based on the needs of the samples.

Finally, a suggestion for additional research is to look in to the research method and intra-

familial samples. This is to distinguish whether these two factors do influence the outcome of the

study.

Conclusion

As a conclusion, there is no significant relationship between birth order and intelligence

in the context of Malaysian children. Despite these results, the last-born child is shown to have a

wider field of knowledge (verbal and non verbal knowledge) compared to the other birth order

categories. On the other hand, this does not entirely degrade the other children in the family as

they too have the advantage in the acquisition of verbal knowledge (reasoning and general

knowledge).


REFERENCES

1. Book

Baron R. A. & Kalsher M. J. (2002). Essentials of Psychology, 3rd ed., United States of America:

Allyn and Bacon.

Galton, F. (1874, 1895). English men of science: Their nature and nurture. New York: D.

Appleton and Company

Hetherington E. M., Parke R. D., Gauvain M. & Locke V. O. (2006). Child Psychology; A

contemporary viewpoint, 6th ed., New York: McGraw-Hill.

Kaufman A. S. & Kaufman N. L. (2004). Kaufman Brief Intelligence Test, 2nd ed. AGS

Publishing.

Leman, K. (1985). The Birth Order Book: Why You Are the Way You Are. New York: Dell

Publishing, pp. 4-5.

Oxford University Press (2000). Encyclopedia of Psychology, Volume 1.

Reber A. S. & Reber E. S. (2001) Dictionary of Psychology, 3rd ed., England: Penguin

References.

Rodgers J. L., Cleveland H. H., Oord E., and Rowe D, American Psychologist, Vol. 55, No. 6.

June 2000. Resolving the Debate Over Birth Order, Family Size and Intelligence".

Sternberg (2006). Cognitive Psychology, 4th ed., Belmont, United States of America: Thomson

Wadsworth.

Wade C. & Tavris C. (2002). Invitation to Psychology, 3rd ed., New Jersy, United States of

America: Pearson Education LTD.

Wood S. E., Wood E. G. & Boyd D. (2004). Mastering the World of Psychology, United States

of America: Pearson Education, Inc.


Zajonc, R. B. (2001). The family dynamics of intellectual development. American Psychologist,

56, 490-496.

2. Web document

Arthur Hu (n.s.) Intelligence: Diversity. Retrieved February 21, 2007 from

http://www.arthurhu.com/INDEX/aintell.htm

Bainbridge C. (2007). Intelligence. Retrieved January 20, 2007, from

http://giftedkids.about.com/od/glossary/g/intelligence.htm

Boeree C. G. (2006). Alfred Adler. Retrieved March 2, 2007, from

http://webspace.ship.edu/cgboer/adler.html

Brockenbrough M. (2007) Is Birth Order Destiny? Retrieved February 20, 2007, from

http://encarta.msn.com/encnet/features/columns/?article=birthordermain

Carey B. (2007). I Am Worm, Hear Me Roar. Retrieved December 16, 2007 from

http://www.nytimes.com/2007/07/01/weekinreview/01carey.html

Child Development Institute (2007). Birth Order. Retrieved February 29, 2008 from

http://www.childdevelopmentinfo.com/development/birth_order.htm

Clayton R. K. (1998). Birth Order and Education. Retrieved December 29, 2007 from

http://clearinghouse.missouriwestern.edu/manuscripts/17.asp

Doe C. Q. (2001) How Brain Cells "Remember" Their Birth Order. Retrieved February 20, 2007,

from http://www.hhmi.org/news/doe.html

Evans J. E. & McClintic M. (2002). Does Birth Order Impact Intelligence?, Missouri Western

State University, Retrieved January 20, 2007, from



Gardner H. (n.s.). The Nine Types of Intelligence. Retrieved January 26, 2007, from

http://skyview.vansd.org/lschmidt/Projects/The%20Nine%20Types%20of%

20Intelligence.htm

Guastello D. D. & Guastello S. J., JASNH, Vol. 1, No. 1, 2002. Birth Order Category Effects on

the Gordon Personal Profile Variables. Retrieved February 21, 2007 from

http://www.jasnh.com/a1.htm

Harris J. R. (2001). Why Are Birth Order Effects Dependent on Context? Retrieved February 21,

2007 from http://xchar.home.att.net/tna/birth-order/context.htm

Hopkins W. G. (2000). Quantitative Research Design. Retrieved February 23, 2008 from

http://sportsci.org/jour/0001/wghdesign.html

Huitt W. (1999). Intelligence. Retrieved February 21, 2008 from

http://chiron.valdosta.edu/whuitt/edpsyppt/Theory/sternberg.ppt.

Kristensen P. & Bjerkedal T., Science, Vol. 316, no. 5832, June 2007. Explaining the Relation

Between Birth Order and Intelligence. Retrieved December 16, 2007 from

http://www.sciencemag.org/cgi/content/short/316/5832/1717

Leman K.(2005) Birth order: What is "birth order"? Retrieved January 20, 2007 from

http://pbskids.org/itsmylife/family/birthorder/

MacCallum R. C., Rodgers J. L. & Wichman A. L. (2007). Birth Order Has No Effect on

Intelligence: A Reply and Extension of Previous Findings. Retrieved December 16, 2007

from

Needlman R. (2001). Birth Order: The Basics. Retrieved January 20, 2007, from

http://www.drspock.com/article/0,1510,5550,00.html?r=related


Princeton University WordNet (2008). Conceptual Definition. Retrieved January 25, 2008, from

http://www.123exp-beliefs.com/t/00804212835/

Princeton University WordNet (2008). Operational Definition. Retrieved January 25, 2008, from

http://www.123exp-science.com/t/01554084699/,operational%20definition,Operational

%20definition

Rimm S. (2002). The Effects of Sibling Competition. Retrieved February 18, 2008, from

http://www.sylviarimm.com/article13.html

Roulinski A. (2007). What is Intelligence? Retrieved January 29, 2007, from

http://ezinearticles.com/?What-is-Intelligence?&id=455211

Safyer P. (2007). Does Birth Order Affect Intelligence? Retrieved December 16, 2007, from

http://serendip.brynmawr.edu/exchange/node/1445

ScienceDaily (2007). Older Children Not Smarter than Their Younger Sibs, Study Finds,

Retrieved January 20, 2007, from

http://www.sciencedaily.com/releases/2006/04/060411230021.htm

Stein H. T. (n.s). Questions and Answers About Classical Adlerian Psychotherapy. Retrieved

March 4, 2007, from http://ourworld.compuserve.com/homepages

Sulloway F. J. (n.s.). Birth Order, Sibling Competition, and Human Behavior. Retrieved March

5, 2007, from http://www.sulloway.org/Holcomb.pdf

Sulloway, F.J. (1996). Born to rebel: Birth order, family dynamics and creative lives. New York:

Pantheon Books.

Walton J. L. (2001). The effect of Birth Order on Intelligence, Loyola University New Orleans,

Retrieved January 19, 2007, from



Wichman A. (2006). Older Children Not Smarter Than Their Younger Sibs. Retrieved March 5,

2007, from http://researchnews.osu.edu/archive/biorder.

Wilson L. O. (2005). Sternberg's Theory of Triarchic Intelligence. Retrieved February 3, 2008,

from http://www.uwsp.edu/Education/lwilson/learning/STERNB1.htm

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