EJ1398172

Journal of Pedagogical Research
Volume 7, Issue 4, 2023

https://doi.org/10.33902/JPR.202320992
Research Article
Differential and interactional influence of socio-
demographic variables on intellectual ability
Stella Eteng-Uket1 and Betty-Ruth Ngozi Iruloh2 1
1 Department of Educational Psychology, Guidance and Counselling, University of Port Harcourt, Nigeria (ORCID: 0000-0001-7042-4894)
2 Department of Educational Psychology, Guidance and Counselling, University of Port Harcourt, Nigeria (ORCID: 0009-0006-7867-8403)
Intellectual ability, also known as intelligence, is a multifaceted construct that is typically measured
through intelligence tests. The importance and complexity of intellectual ability have made it of significant
interest to researchers and educators. This is coupled with the fact that it is one phenomenon that is
influenced by a variety of factors. This prompted the study that sought to investigate the differential and
interactional influences of gender, age, education, and ethnicity on intellectual ability in Rivers State
Nigeria. The study employed the analytic descriptive survey design with a sample of 390 that was
randomly drawn using a stratified sampling technique. A test of general reasoning ability, which is a
standardized test, was used to elicit data on the variables of the study. Validity and high reliability
coefficients were obtained for the instrument. Data were analysed using mean, standard deviation, t-test,
one-way, and three-way ANOVA. The result showed that age and ethnicity had a significant influence on
intellectual ability, but gender and educational level did not have a significant influence. Gender, age, and
educational level did not have significant interactional influences as well. It was recommended that
investing in education, particularly in the early years, can have lasting benefits for cognitive and
intellectual ability development.
Keywords: Intellectual ability; Gender; Age; Education; Ethnicity
Article History: Submitted 4 March 2023; Revised 30 July 2023; Published online 24 August 2023
1. Introduction
Intellectual ability, also known as cognitive ability or intelligence, is a multifaceted construct that
has been of interest to researchers and scholars for centuries. It is a broad term that refers to the
mental capacity to learn, reason, and solve problems. It is a complex construct that encompasses a
range of cognitive skills, including memory, attention, language, critical thinking, and problem-
solving. Intelligence is the ability to derive information, learn from experience, adapt to the
environment, understand, and correctly utilize thought and reason (American Psychological
Association [APA], 2020). It is a very general mental capability that among the other things,
involves the ability to resume, plan, solve problems, think abstractly, comprehend complex ideas,
quickly learn from experience. (Gottfredson, 1997)
Address of Corresponding Author
Stella Eteng-Uket, PhD, Department of Educational Psychology, Guidance & Counselling, University of Port Harcourt, 5323 Choba,
Rivers State, Nigeria.
Stella.eteng-uket@uniport.edu.ng
How to cite: Eteng-Uket, S. & Iruloh, B. R. N. (2023). Differential and interactional influence of socio-demographic variables on
intellectual ability. Journal of Pedagogical Research, 7(4), 111-130. https://doi.org/10.33902/JPR.202320992
S. Eteng-Uket & B.R.N. Iruloh / Journal of Pedagogical Research, 7(4), 111-130 112
Intellectual ability or intelligence is typically measured through intelligence tests. There is a

significant body of research demonstrating the importance of intellectual ability in a number of
domains. For example, studies have consistently found that individuals with higher levels of
intelligence tend to have better academic outcomes, including higher grades, test scores, and
graduation rates (Deary et al., 2007; Hegelund et al., 2018; Hegelund et al., 2020; Jensen, 1998; Roth
et al., 2015; Strenze, 2007), Additionally, intelligence is strongly correlated with job performance,
with research indicating that individuals with higher levels of intelligence are more likely to
perform well in their jobs and have higher levels of job satisfaction and higher adult financial well-
being (Furnham & Cheng, 2016, 2017; Hunter & Schmidt, 1996; Kuncel & Hezlett, 2010; Schmidt &
Hunter, 1998).
Intellectual ability has also been found to be related to social outcomes. For instance, research
has found that individuals with higher levels of intelligence tend to have better interpersonal skills
and are more likely to form and maintain close relationships (Deary, 2001). There is also evidence
to suggest that intelligence is related to overall financial well-being, physical and mental health
(Furnham & Cheng, 2016, 2017; Gale et al., 2012; Wrulich et al., 2014). They are also more likely to
have a positive outlook on life and to be more resilient in the face of stress and adversity
(Sternberg, 2003).
Overall, the research suggests that intellectual ability is an important predictor and positively
associated with a range of outcomes, such as educational (Ceci, 1991; Clouston et al., 2012; Deary et
al., 2007; Hedden & Gabrieli, 2004; Hegelund, et al., 2018; Hegelund et al., 2020; Jensen, 1998;
Ritchie & Tucker-Drob, 2018; Roth et al., 2015; Strenze, 2007), physical, financial and mental health
(Furnham & Cheng, 2016; Gale et al., 2012; Sternberg, 2003; Wrulich et al., 2014), longevity (Calvin
et al., 2017; Christensen et al., 2016), performance at work, occupational health and job satisfaction
and financial well-being(Calvin et al., 2017; Furnham & Cheng, 2016, 2017; Kuncel & Hezlett,
2010), and other areas like administration and governance, marriage, family life and the likes
The importance and complexity of intellectual ability has made it of significant interest to
researchers and educators. This is coupled with the fact that it is one phenomenon that is
influenced by a variety of factors which can impact its influences and effects on other phenomenon
in different ways and to varying degrees. Research has consistently revealed that genetic and
environmental factors like socio-demographic factors play significant roles in intellectual abilities.
Socio-demographic variables play a crucial role in understanding and analysing the diverse
characteristics of individuals. Socio-demographic variables encompass a range of factors that
capture an individual's social and demographic characteristics. These variables include but are not
limited to age, gender, race, ethnicity, socioeconomic status, parental education level, and cultural
background. Each of these variables contributes unique information about individuals. By
examining socio-demographic variables, researchers can gain valuable insights into patterns,
trends, and disparities across different groups, leading to a better understanding of individuals.
Literature has shown that each of these variables has been found to be associated with intellectual
ability, either independently or through their interactions. Specifically, it is influenced by a range
of factors including age, education, gender, ethnicity, personality, socio-economic status just to
mention but a few (Plomin et al., 2008).
1.1. Age and Intellectual Ability
Age is one factor that can influence intellectual ability. It is a measure of the time that an
individual has been alive, typically measured and expressed in years. The relationship between
age and intellectual ability is complex and varies depending on the specific cognitive domain
being measured and the age range being considered. Research has shown that intellectual and
cognitive function tends to increase during childhood and adolescence before peaking in the late
teenage years or early 20s, and then declining slightly in later life (Gow, 2016; Hedden & Gabrieli,
2004; Salthouse, 2010). This is thought to be due to the gradual loss of neurons and the brain's
declining ability to regenerate new ones However, there is significant variability in the rate of
intellectual development and decline among individuals, and factors such as genetics, health and
lifestyle, and environmental influences can influence the rate of decline (Hedden & Gabrieli, 2004;
Park & Reuter-Lorenz, 2009; Salthouse, 2010).
Research suggests that engaging in complex cognitive activities may slow the rate of decline in
cognitive function (Wilson et al., 2002). Therefore, while age is an important factor, the relationship
between age and intellectual ability is complex and influenced by a range of other factors
(Cockburn & Smith, 1991; Hedden & Gabrieli, 2004; Park & Reuter-Lorenz, 2009; Salthouse, 2010;
Schaie, 1996; Wilson et al., 2002). Overall, the research suggests that age is a significant factor that
can influence intellectual ability, but the relationship between age and intellectual ability is
complex and influenced by a range of other factors.
1.2. Gender and Intellectual Ability
One other factor that has long been thought to potentially influence intellectual ability is gender.
Gender is the set of social, cultural, and psychological characteristics associated with being male or
female. There have been numerous debates and discussions throughout history about whether
men and women differ in their intellectual abilities and, if so, to what extent (Lippa, 2005). In the
past, some people believed that men were inherently more intelligent than women. This belief was
often used to justify the exclusion of women from education and certain occupations (Sadker &
Sadker, 1994). In the 19th and early 20th centuries, for example, women were often discouraged
from pursuing careers in science, math, and other fields that were seen as requiring high levels of
intelligence (Schiebinger, 1999). However, as research on intelligence and sex differences has
progressed, so has understanding of the relationship between gender and intellectual ability
changed. (Halpern, 2000). Large body of research has shown that men and women do not differ
significantly in their overall intellectual abilities. That is most researches on sex difference and
intelligence have posit that gender differences were either the same or so negligibly small and that
no significant difference exits between male and female on intelligence test (Brody 1992;
Herrnstein & Murray, 1994).
This consensus was disputed by Lynn (1994), who advanced a developmental theory of sex
differences in intelligence stating that while there is virtually no sex difference up to the age of 16
years, from this age onwards males develop an advantage that increases with age reaching
approximately 4 IQ points among adults (Lynn, 1994). Further data documenting this male
advantage was given in Lynn (1998), Lynn (1999), Lynn et al., (2000), Lynn and Tse-Chan (2003),
Lynn, et al., (2004), Colom and Lynn (2004), Irwing and Lynn (2005) and in a meta-analysis of sex
differences on by Lynn and Irwing (2004) concluding that among adults’ males obtain a 5 points
higher IQ than females. This is also followed by the research findings of Lynn and Kanazawa
(2011) in which results show that at the ages of 7- and 11-years girls have an IQ advantage of
approximately 1 IQ point, but at the age of 16 years this changes in the same boys and girls to an
IQ advantage of 1.8 IQ points for boys. These findings seem to be supported by the result from
Nyborg (2005) and Jackson and Rushton (2006) and Lemos et al. (2013) whose studies showed sex
difference in intelligence. However, significant portion of research findings have constantly
revealed that no significant sex difference exists between male and female intellectual ability
(Anderson, 2004; Aluja-Fabregat et al., 2000; Butterworth, 1999; Carretta & Ree 1997; Cooper, 2015;
Colom, et al., 2000; Colom & Garc´ıa-López 2002; Colom et al., 2002; Dolan et al., 2006; Deary et
al., 2007; Flynn, 1998; Haier, 2007; Halpern & LaMay, 2000; Halpern, 2000, 2007; Hyde et al., 1990;
Hines, 2007; Hyde et al., 1990; Jensen, 1998; Keith et al 2008; Mackintosh, 2011; Naderi et al., 2008;
Ritchie, 2015; Speke, 2007; van der Sluis et al., 2006; Voyer et al., 1995).
Research has also shown that, when other factors such as education and socio-economic status
are controlled for, men and women perform similarly on a wide range of cognitive tasks (Davies et
al., 2005). It is therefore important to note that any observed differences in intellectual ability
between men and women may be influenced by a variety of other factors, such as education, socio-
economic status, societal and cultural expectations. For instance, societal and cultural factors, such
as gender roles and stereotypes, can influence the development of intellectual ability. Also these
stereotypes, discrimination, bias and societal expectations can act as barriers to education and
career advancement for certain groups especially females and also from pursuing certain fields of
study (Casad et al., 2017; Schiebinger, 1999; Shapiro & Williams 2005). They can shape the
expectations and opportunities that are available to men and women. For example, women may
score lower on certain cognitive tests due to a lack of access to education. As earlier stated, the
debate as to whether men and women differ in their intellectual abilities and, if so, to what extent
is one that is still ongoing in the research community. However, more research is needed to
establish more conclusive positions especially from areas and regions of the world where evidence
of sex difference in intellectual abilities is scarce and also in relation to its interaction with other
factors that may influence the difference if at all one is observed.
1.3. Education and Intellectual Ability
Education is another factor that may influence intellectual ability. It is a broad term that can
encompass many different types of learning, including formal schooling, informal learning, and
experiential learning. It is also the process of acquiring knowledge, skills, values, beliefs, and
habits through formal and informal learning experiences. Education exposes individuals to a wide
range of stimuli and challenges that stimulate the brain and promote intellectual and cognitive
development. Through interactions with teachers and peers, and exposure to diverse ideas and
concepts, individuals are able to develop higher-order thinking skills and knowledge that are
essential for intellectual ability. That is, educational experiences can provide individuals with the
knowledge, skills, and critical thinking abilities that are necessary for success in a variety of
cognitive and intellectual tasks. It plays a pivotal role in shaping the cognitive skills, knowledge,
and critical thinking abilities of individuals. Within the framework of the International Standard
Classification of Education [ISCED] by the United Nations Educational, Scientific, and Cultural
Organisation (UNESCO, 2011), levels of education are an ordered set of categories, intended to
group educational programs in relation to gradations of learning experiences and the knowledge,
skills and competencies which each program is designed to impart. Levels of education are
therefore a construct based on the assumption that education programs can be grouped into an
ordered series of categories. These categories represent broad steps of educational progression in
terms of the complexity of educational content. The more advanced the program, the higher the
level of education. In most countries of the world, specifically in Nigeria, the educational levels
are; the Primary and Secondary Education level which leads to the award of Senior School
Certificate [SSC] or the West African Senior School Certificate [WASSC], the tertiary Education
level which consist of the undergraduate education that leads to the award of a B.Sc. and post
graduate education that climax in a Ph.D. certificate
Education is a crucial factor in the development of intellectual ability. Research has consistently
demonstrated the positive relationship between education and intellectual ability. Higher levels of
education are associated with better intellectual and cognitive skills, higher levels of knowledge,
and improved critical thinking abilities. Higher levels of education are often associated with better
cognitive skills and performance on intelligence tests. The review of the literature suggests that
education has a significant influence on intellectual ability (Ceci, 1991; Clouston et al., 2012; Deary
et al., 2007; Deary & Johnson 2010: Furnham & Cheng, 2017; Halpern, 1998; Hegelund et al., 2018;
Hegelund, et al., 2020; Jensen, 1998; Kocaöz & Yalçın, 2022; Roth et al., 2015; Strenze, 2007).
Generally, the literature review suggests that education influences intellectual ability. However,
more research is needed to fully understand other underlying mechanisms that drive the
relationship between education and intellectual ability. This includes examining the influence of
other factors in addition to education that may influence intellectual ability.
1.4. Ethnicity and Intellectual Ability

The issue of the influence of ethnicity on intellectual ability is a complex one. Ethnicity is a social
identity based on shared ancestry, culture, and experiences. It is a multifaceted idea, which figures
the identity of an individual through kinship, religion, language, shared territory and nationality,
and physical appearance. (Dein 2006; Mateos 2007). Ethnicity as a concept involves some form of
identification, individual identify themselves as belonging to a certain group and the group
recognizes individual as belonging to that group (Ogbogo & Opara, 2019). Different parts of the
world usually have majority ethnic group as well as minority ethnic groups. Ethnicity is often
considered as a potential factor that may impact intellectual ability, but research on this topic has a
long and controversial history.
Early intelligence research, which dates back to the early 20th century, often found evidence of
differences in intelligence test scores between racial and ethnic groups. The debate and
controversies on intellectual ability and ethnicity became worldwide in scope when it was shown
that East Asians scored higher on IQ tests than did Whites, both within the United States and in
Asia, even though IQ tests were developed for use in the Euro American culture (Rushton &
Jensen, 2005). Around the world, the average IQ for persons from East Asians, United States and
sub-Saharan Africa differs (Furnham et al., 2010; Jensen, 1998; Lynn & Vanhanen, 2002; Rushton,
2000; Rushton, & Jensen, 2005). Lynn’s (1991) review of 11 studies in sub-Sahara Africa also
revealed different IQ scores for the persons in the sub-Sahara African and other parts of the world.
Also, review of over two dozen studies by Lynn and Vanhanen (2002) found same average IQ
scores for persons from West, Central, East, and Southern Africa against a different IQ score from
those from the US. The same difference in IQ between persons from different nations were
obtained from the study of Glewwe and Jacoby (1992), Sternberg et al. (2001), Zindi (1994), Owen
(1992), Grieve and Viljoen (2000), Skuy et al. (2001), Zaaiman et al. (2001), Rushton and Skuy
(2000), and Skuy et al. (2002).
Although it has been reported that some of the differences in intelligence test scores between
racial and ethnic groups may be due to biases in the tests themselves. These biases may be related
to the cultural experiences and backgrounds of the test takers, or to the ways in which the tests are
designed and administered. Report has also noted that these differences are often small and may
be influenced or due to a variety of factors such as access to education and socio-economic status,
gender, nutrition, and other resources, as well as cultural values and beliefs about the importance
of intellectual development. Proceeding discuss suggest that ethnicity may play a role in
intellectual abilities, it is not the only factor, and further research is needed to understand the
complex interactions between ethnicity and other factors like educational level, age and gender.
1.5. The Present Study
Understanding the factors that influence intellectual ability is important for a variety of purposes
one of which is that it has major influence on the outcome on domains like education, occupation
health, longevity, marriage and the likes as has been evidenced by research from preceding
discuss. The influence of age, gender, and ethnicity on intellectual ability is a topic that has
garnered significant attention in the field of psychology and education as can be deduced from
research evidence in preceding discuss. While it is widely acknowledged that these factors can
have some impact on intellectual ability, the extent to which they do so is still a subject of debate.
Further research is needed to better understand the complex interactions between these factors and
the ways in which they may influence intellectual abilities. Also, researches on the influence of
gender, age, ethnicity and educational level on intelligence about sex differences are based almost
exclusively on results from modern western societies. It does not take account of the possibility
that there could be systematic differences between countries with different school systems, cultural
traditions, and gender roles especially in Sub Sahara regions like Nigeria. Thus, there is an urgent
need to expand the evidence base on which policies and decisions about the influence of these
variables on intelligence are built by including results from regions that are not in literature. All
these created a gap that needed to be filled. The foregoing is where the significance of this study
lies as well as its contribution to knowledge. That is, it is significant and contributes to knowledge
by clarifying the extent of influence that age, gender, educational level, and ethnicity have on
intellectual ability. Furthermore, it expands the evidence base beyond Western societies and fills a
gap in understanding, providing valuable insights for future research, policies, and decision-
making in the field of intelligence and socio-demographic factors. These were what necessitated
this research which is aimed at investigating the differential and interactional influences of socio-
demographic factors of age, gender, educational level and ethnicity on intellectual ability. The
following research questions guided the study;
RQ 1) Is there a significant influence of gender on intellectual ability?
RQ 2) Is there any significant influence of age on intellectual ability?
RQ 3) Is there any significant influence of educational level on intellectual ability?
RQ 4) Does ethnicity have any significant influence on intellectual ability?
RQ 5) Is there any significant interaction influence of age, gender, educational level and
ethnicity on intellectual ability?
2. Methodology
2.1. Research Design
The research design was the descriptive survey. Within this design, the analytic descriptive design
was employed. This design is suitable when comparisons are to be made between various strata of
a sample for the variables that are being studied (Nwankwo, 2013).
2.2. Participants
The population of the study covers all male and female from primary, secondary and tertiary
educational level with age ranges from 10 to 31years above from both minority and majority ethnic
groups in Port Harcourt Metropolis, Rivers State. Through disproportionate stratified random
sampling technique, a sample of 380 was drawn to cover four age groups (10- 20yrs, 21- 30yrs, 31-
40, 40 above), gender (male and female), two ethnic category (minority and majority) and three
educational levels (primary, secondary and tertiary) (see Table 1).
Table1
Demographic information of the sample for the study
Demographic Information N %
Gender
Male 134 34
Female 256 66
Age
10-20yrs 134 34
21-31yrs 163 42
31-40yrs 40 10
41yrs Above 53 14
Ethnicity
Majority 256 66
Minority 134 34
Educational Levels
SSC/WASSC 236 60
B.SC 135 35
MSC& Ph.D 19 5
The study sample comprised 390 participants, out of these, 134 participants identified as male,
constituting approximately 34% of the total sample, while 256 participants identified as female,
representing 66% of the total sample. The age distribution of the participants in the study showed
that 10-20 years had 134 participants representing 34%, 21-31 years had 163 participants
representing 42%, 31-40 years has 40 participants representing 10% and participants 41 years and
above were 53 participants representing 14%.
2.3. Instrument for Data Collection
The instrument for data collection was the Test of General Reasoning Ability [TOGRA] by Reynold
(2014), the TOGRA is a speeded measure of reasoning and intellectual abilities as well as problem-
solving skills. It consists of items that assess verbal skills, nonverbal skills, quantitative reasoning,
and problem-solving skills through tasks that are inductive and deductive in nature. The Test of
General Reasoning Ability (TOGRA) is a flexible and effective assessment that measures general
reasoning and problem-solving skills in about 16 minutes and is scored in 2 to 3 minutes. It can be
administered to an individual or to groups in a variety of settings. It contains 60 items with each
items containing options lettered A-E. TOGRA items are dichotomously scored with the right
answer scored 1 and the wrong answers scored 0. It is a timed test designed for individuals aged
10 to 75 years. Figure 1 shows a sample of item from the test.
Figure 1
Sample item
TOGRA have internationally been acclaimed validity. TOGRA was standardized on a sample of
3,013 individuals in US. The test has .75 to .95 as construct validity via correlation with another
test (RAIT), (WISC-IV), WAIS-IV), (RIAS), Wonderlic, (Beta III), (WRAT), (TIWRE).
The reliability for TOGRA as reported by Reynold (2014) ranges from 0.74 to 0.99 from ages 10
to 75 for test-retest reliability, .87 to .94 from ages 10 to 75 for Cronbach alpha reliability, .85 to .94
for alternate form reliability. Although the above instrument has known reliabilities, the researcher
however carried out a pilot study. Thus, the reliability of the instrument was reestablished through
pilot testing. The reliability of the instrument was established using various reliability methods,
Parallel form yielded a coefficient of .617; split-half reliability analysis yielded a coefficient of .677
while Cronbach alpha yielded a coefficient of .904.
2.4. Data Analysis
TOGRA was administered to the respondents directly. Ethics was taken into consideration in the
course of this research. Respondents were duly briefed on the research and the instruments they
were going to respond to. They gave their consent by filling an informed consent form.
Respondents were assured of their privacy by telling them that the information provided would be
kept confidential and strictly used only for research purpose. Furthermore, the coded information
was kept on computers accessible only to the researchers and protected with a security system to
prevent unauthorized access to the collected data. Data obtained was cleaned. Normality test was
carried out on the data. The test showed skewness coefficient to be .97 while the kurtosis
coefficient was .743. This test result showed that the distribution for the study did not fall outside
the range of normality, so the distribution was considered normal. These statistical data depict the
normal distribution of the scores (Byrne 2010; George & Mallery, 2010; Hair et al., 2010, 2022;
Tabachnick & Fidell, 2013). The data for the study fulfilled the assumption of normal distribution,
thus mean, standard deviation, independent samples t-test, one way, and three-way ANOVA was
used to analysed the data. All these analyses were conducted through Statistical Package for the
Social Sciences (SPSS) version 21.
3. Results
3.1. Result on the Influence of Gender on Intellectual Ability
Table 2 shows the result of independent samples t-test analysis of influence of gender on
intellectual ability
Table 2
Independent samples t-test results of influence of gender on intellectual ability
Gender N Mean SD df t Sig. Decision
Male 134 20.30 11.68 Accept Ho1
388 1.121 .263
Female 256 19.02 10.18 𝑝 > .05
The table reveals that the males have a mean score of 20.30 representing their intellectual ability
while the females have 19.02 representing their intellectual ability. The difference in the means
scores of these groups shows that on the average, the intelligence of male and female differs as
represented by their IQ scores on the intelligence test administered. A comparison of these two
means shows there is difference between the mean score of male and female. The difference which
is higher for the male as seen by the mean of 20.30 to the mean score of females which was 19.02,
reveals that on the average, the IQ of males are slightly higher than female as there is a mean
difference of 1.28.
The table reveals as well shows that t(388) = 1.121 𝑝 > .05, i.e., 𝑝 = .263 is greater than .05 and
this is statistically not significant at the chosen alpha level of .05. This implies that though there is a
difference in the average IQ scores of male and female persons in Port Harcourt metropolis, this
difference is not statistically significant.
3.2. Result on the Influence of Age on Intellectual Ability
Table 3 shows the result of one-way ANOVA analysis analysis of influence of age on intellectual
ability
Table 3
One-way ANOVA analysis of influence of age on intellectual ability
Age N Mean SD df Mean Square F Sig. Decision
10-20yrs 134 20.51 10.23
21-30yrs 163 20.53 11.87 3.386 112.366 4.188 .006 Reject Ho1
31-40yrs 40 16.00 8.277 𝑝 < .05
41 above 53 16.11 8.681
As shown by the mean scores of 20.51, 20.53, 16.00 and 16.11, persons between the ages of 10-20,
21-30, 31-40 and 40 years above have varying levels of intelligence. The varying intelligence scores
shows there is a difference in the intellectual ability and invariably intelligence of persons across
the different age groups covered in this study. Persons between the ages of 10-20 and 21-30 had
almost identical average intelligence score (mean 20.51 and 20.53 respectively). This was also same
for persons between 31-40 and40 above (16.00 and 16.11 mean scores, respectively). A comparison
of the means of these four age groups shows there is difference between the mean score of these
groups. The difference in the means scores of these groups shows that on the average, the
intelligence of persons across these age groups differs as represented by their IQ scores on the
intelligence test administered. As shown by the mean score of 20.5 compared to 16.00 for those
between the ages of 31-41 and above, the difference was greater among persons between the ages
of 10-30. This indicates that on the average, the intelligence of persons aged 10-30 is higher than
persons from age 31-40 and above for persons in Port Harcourt metropolis.
The table reveals as well shows that the computed F(3, 388) = 4.188, 𝑝 < .05, i.e., 𝑝 = .006, i.e.,
𝑝 = .006 is less than .05 and this is statistically significant at the chosen alpha level of .05. This
implies that there is a difference in the average IQ scores of persons between age 10-20, 21-30, 31-
40 and 40 above and this difference is statistically significant. That is statistical evidence shows that
the difference observed between these age groups average intelligence is not due to chance
occurrence.
3.3. Result on the Influence of Educational Qualification on Intellectual Ability
Table 4 shows the result of one-way ANOVA analysis of influence of educational qualification on
intellectual ability.
Table 4
Mean, SD and One-way ANOVA Analysis of influence of educational level on intellectual ability
Edu Level N Mean SD df Mean Square F Sig. Decision
SSC 236 19.94 10.89
Accept Ho1
B.Sc. 135 18.14 11.08 2.387 249.706 2.182 .114
𝑝 > .05
Ph.D. 19 22.78 12.3
Note. SSC: Senior School Certificate
Table 4 reveals that persons with SSC, B.Scs. and Ph.Ds. have varying intelligence scores
represented by the mean scores of 19.94, 18.14, and 22.78 respectively. The varying intelligence
scores shows there is a difference in the intellectual ability and invariably intelligence of persons
from the three educational levels covered in this study. Persons with SSC educational level had
average mean score of intelligence, 20.51, while persons with B.Sc. had a mean score of 18.14 and
those with Ph.D. 22.78. The difference in the means scores of these groups shows that on the
average, the intelligence of persons across these educational levels differs as represented by their
IQ scores on the intelligence test administered. A comparison of these means shows there is
difference between the mean score of these three educational levels. The difference was higher for
persons from educational level with Ph.D. generally as seen by the mean score of 22.78 and lowest
for persons with B.Sc., 18.14. This indicates that on the average, the intelligence of persons with
Ph.D. educational level is higher than persons with B.Sc. and SSC in Port Harcourt metropolis.
The table reveals as well shows that the computed F (2, 387) = 2.182, 𝑝 < .05, i.e., 𝑝 =.114, i.e.,
𝑝 = .114 is greater than .05 and this is statistically not significant at the chosen alpha level of .05.
This shows that there is no difference in the average IQ scores of persons from SSCE, B.Scs. and
Ph.D. educational level and this difference is statistically not significant.
3.4. Result on the Influence of Ethnicity on Intellectual Ability
Table 5 shows the result of independent samples t-test analysis of influence of ethnicity on
Table 5
Independent samples t-test analysis of influence of ethnicity on intellectual ability
Ethnicity N Mean SD df t Sig. Decision
Minority 134 18.59 9.891 388 2.215 .027 Reject Ho1
Majority 256 21.11 12.03 𝑝 < .05
According to Table 5, people from minority ethnic groups had a mean score of 18.59, while
people from majority ethnic groups had a mean score of 21.11. The difference in the means scores
of these groups shows that on the average, the intelligence of persons from the both ethnic groups
differ as represented by their IQ scores on the intelligence test administered. A comparison of
these two means shows there is difference between the mean score of these two ethnic groups. The
difference which is higher for the majority ethnic as seen by the mean score of 21.11 reveals that on
the average, the IQ of majority ethnic groups are slightly higher than the minority group as there is
a mean difference of 2.52.
It also shows that t(388) = 2.215, 𝑝 < .5, i.e., p = .027 which is statistically significant at the
chosen alpha level of 0.05. This implies that the difference in the average IQ scores of minority and
majority ethnic groups in port Harcourt metropolis is statistically significant.
3.4. Result on the Influence of Ethnicity on Intellectual Ability
Table 5 illustrates the t-test results for independent samples on the influence of ethnicity on
intellectual ability.
Table 5
Independent samples t-test analysis of influence of ethnicity on intellectual ability
Ethnicity N Mean SD df t Sig. Decision
Minority 134 18.59 9.891 388 2.215 .027 Reject Ho1
Majority 256 21.11 12.03 𝑝 < .05
Those from minority ethnic groups had a mean score of 18.59 representing their intellectual
ability, while those from majority ethnic groups had a mean score of 21.11. The difference in the
means scores of these groups shows that on the average, the intelligence of persons from the both
ethnic groups differ as represented by their IQ scores on the intelligence test administered. A
comparison of these two means shows there is difference between the mean score of these two
ethnic groups. The difference which is higher for the majority ethnic as seen by the mean of 21.11
to the mean score of the minority ethnic group which was 18.59, reveals that on average, the IQ of
majority ethnic groups is slightly higher than the IQ of minority ethnic groups, with a mean
difference of 2.52.
The table reveals that t(388) = 2.215, 𝑝 < .5, i.e., 𝑝 = .027 is less than .05. This implies that the
difference in the average IQ scores of minority and majority ethnic groups in port Harcourt
metropolis is statistically significant.
3.5. Result on the Interaction Influence of Age, Gender, and Educational Level on Intellectual
Ability
Table 6 shows the result of analysis of influence of ethnicity on intellectual ability.
Table 6
Results on the interaction influence of age, gender, and educational level on intellectual ability
Gender Age Edu Level Mean Std. Deviation N
Male 10-20YRS SSC 23.58 11.24 31
BSC 12.00 . 2
PHD .
Total 23.36 11.10 33
20-30YRS SSC 27.48 13.35 27
BSC 17.18 11.14 33
PHD 20.50 14.84 2
Total 21.77 13.06 62
30-40YRS SSC 14.66 4.72 3
BSC 16.44 9.36 9
PHD 8.50 2.12 2
Total 14.92 8.10 14
40ABOVE SSC 13.50 7.89 12
BSC 16.44 9.38 9
PHD 20.25 3.50 4
Total 15.64 8.09 25
Total SSC 23.00 12.36 73
BSC 16.82 10.29 52
PHD 18.55 8.45 9
Total 20.3060 11.68781 134
Table 6 continued
Gender Age Edu Level Mean Std. Deviation N
Female 10-20YRS SSC 19.64 9.76 87
BSC 17.38 8.20 13
PHD 43.00 . 1
Total 19.58 9.80 101
20-30YRS SSC 19.43 11.39 48
BSC 20.35 11.01 51
PHD 13.50 4.94 2
Total 19.78 11.09 101
30-40YRS SSC 14.00 7.27 10
BSC 15.30 7.07 13
PHD 30.66 4.04 3
Total 16.57 8.46 26
40ABOVE SSC 13.72 4.61 18
BSC 18.66 7.50 6
PHD 26.00 19.71 4
Total 16.53 9.30 28
Total SSC 18.58 9.91 163
BSC 18.97 9.91 83
PHD 26.60 14.47 10
Total 19.02 10.18 256
Total 10-20YRS SSC 20.67 10.27 118
BSC 17.00 8.00 14
PHD 35.50 10.60 2
Total 20.51 10.23 134
20-30YRS SSC 22.33 12.66 75
BSC 19.10 11.10 84
PHD 17.00 9.89 4
Total 20.53 11.87 163
30-40YRS SSC 14.15 6.59 13
BSC 15.77 7.89 22
PHD 21.80 12.51 5
Total 16.00 8.27 40
40ABOVE SSC 13.63 6.00 30
BSC 17.33 8.46 15
PHD 23.12 13.46 8
Total 16.11 8.68 53
Total SSC 19.94 10.89 236
BSC 18.14 10.08 135
PHD 22.78 12.39 19
Total 19.46 10.72 390
The interaction influence of gender, age and educational level is presented in Table 6. It shows
that the most influential interaction was for female between 30-40yrs with Ph.D. educational
qualification with an average intelligence mean score of 30.66. This is followed by that of male,
aged 20-30yrs with SSCE with a mean score of 27.48, followed by that of male, aged 20-30yrs with
SSC with a mean of 27.48, then female who are 40yrs with Ph.D. educational qualification with an
average intelligence mean of 26.00. This is followed by male, aged 10-20yrs with SSCE with a mean
of 23.5, followed by female, aged 20-30yrs with B.Sc. with a mean of 20.35. This followed by the
interaction of male jointly from 31-40 and 40years above with Ph.D. with the same mean of 20.25,
then that of female, aged 10-20yrs with SSC with a mean of 19.64, then female aged 20-30yrs with
SSCE with a mean of 19.43 then male aged 20-30yrs with B.Sc. with a mean of 17.18. This is
followed by the interaction of male jointly from 31-40 and 40 years with B.Sc. and above with the
same mean of 16.44 and then other interactions as can be deduced from the table 5.1. The differing
intelligence scores indicates that male and female from the four age groups (10-20yrs, 21-30yrs, 31-
40yrs, 41 above) from the three educational levels have differing intellectual ability.
3.6. Results on the Interaction Influence of Age, Gender, and Educational Level on Intellectual
Ability
Table 7 shows the result of three-way ANOVA Analysis of the no significant interaction influence
of age, gender, and educational level on intellectual ability.
Table 7
Three-way ANOVA Analysis of the interaction influence of age, gender, and educational level on
Source Type III Sum of df Mean Square F Sig.
Squares
Corrected Model 5858.567 23 254.720 2.395 .000
Intercept 33503.566 1 33503.566 315.012 .000
Gender 166.332 1 166.332 1.564 .212
AGE 471.898 3 112.366 4.188 .006
Edu Level 546.048 2 249.076 2.182 .114
Gender * Age 470.319 3 156.773 1.474 .221
Gender * Edu Level 578.009 2 289.005 2.717 .067
Age * Edu Level 1371.882 6 228.647 2.150 .047
Gender* Age * Edu Level 803.325 6 133.888 1.259 .276
Error 38926.430 366 106.356
Total 192537.000 390
Corrected Total 44784.997 389
The table shows that F(1, 366) = 1.564, 𝑝 < .05, i.e., 𝑝 = .212, i.e., which is greater than .05 and
implies that though there is a difference in the average IQ scores of male and female persons in
Port Harcourt metropolis, this difference is not statistically significant.
The table also reveals as well shows that the computed F (3, 388) = 4.188, 𝑝 < .05, i.e., 𝑝 = .006,
i.e., p = .006 is less than .05 that implies that there is a difference in the average IQ scores of
persons between age 10-20, 21-30, 31-40 and 40 above and this difference is statistically significant.
That is statistical evidence shows that the difference observed between these age groups average
intelligence is not due to chance occurrence.
Another implication from the table was that the computed F(2, 366) = 2.182, 𝑝 < .05, i.e.,
𝑝 = .114 is greater than .05. This value shows that there is no difference in the average IQ scores of
persons from SSCE, B.Scs. and Ph.D. educational level and this difference is statistically not
significant.
The table goes further to shows that the computed F(2, 366) = 1.474, 𝑝 > .05, i.e., 𝑝 = .22. This
implies that there is no significant two-way interactions in the average IQ scores of persons that
are, male and female between age 10-20, 21-30, 31-40 and 40 above and this difference is
statistically not significant. That is statistical evidence shows that the difference observed between
these age groups based on gender average intelligence may be due to chance occurrence
Another result revealed from the table was F(2, 366) = 2.717 𝑝 > .05, i.e., 𝑝 = .067. The value
was found to be greater than 0.05 and this is statistically not significant at the chosen alpha level of
0.05. This implies that there is no significant two-way interactions in the average IQ scores of
persons that are, male and female from SSCE, B.Scs. and Ph.D. educational level and this
difference is statistically not significant. That is statistical evidence shows that the difference
observed from persons from SSCE, B.Scs. and Ph.D. educational level based on gender average
intelligence may be due to chance occurrence
The goes further to shows that the computed F (6, 366) = 2.150, p>.05, i.e., p = .047 i.e., p = .047
is less than 0.05 and this is statistically significant at the chosen alpha level of 0.05. This implies
that there is a significant two-way interaction in the average IQ scores of persons between age 10-
20, 21-30, 31-40 and 40 above with SSC, B.Scs. and Ph.D. educational level. That is statistical
evidence shows that the difference observed from persons from SSCE, B.Scs. and Ph.D. educational
level for persons between age 10-20, 21-30, 31-40 and 40 above average intelligence is not due to
chance occurrence as statistical difference exits.
Finally, it was obtained that F (6, 366) = 1.259, 𝑝 > .05, i.e., 𝑝 = .227, i.e., that implies that there
is no significant three-way interaction between the average IQ scores of persons between male and
female age 10-20, 21-30, 31-40 and 40 above with SSC, B.Scs. and Ph.D. educational level. That is,
the difference observed from male and female with SSC, B.Scs. and Ph.D. educational level for
persons between age 10-20, 21-30, 31-40 and 40 above average intelligence may be due to chance
occurrence as no statistical difference exits. The inference from the above is that neither age nor
gender, nor educational qualification on interaction, has any significant influence on intelligence.
4. Discussion
The result shows that the slight difference that exists between male and female intelligence is not
statistically significant. The result shows that the slight difference that exists between male and
female intelligence is not statistically significant. This result is same as most researches on sex
difference and intelligence that have posited that gender differences were either the same or so
negligibly small and that no significant difference exits between male and female on intelligence
test (Brody 1992; Herrnstein & Murray, 1994). This finding is also in line with the research findings
of so many researches from around the world like Aluja-Fabregat et al., (2000) who found null sex
difference, likewise Carretta and Ree (1997) and Colom et al. (2000). This result is also similar to
that of Colom and García-López (2002) who found no gender difference. In the same vein,
Colom, et al. (2002) found small sex variance likewise Dolan et al., (2006) and Deary et al. (2007)
found no significant sex difference as well. Flynn (1998) and Haier (2007) found a small gender
difference. The same was obtained from Mackintosh (2011). Result for this observed similarity
between the finding of this present study and the ones reviewed, could be that the study sample
and demographic are quite similar to the ones reviewed
Also, slight difference observed in intellectual ability between male and female may be
influenced by a variety of other factors, such as education, age, socio-economic status, societal and
cultural expectations. For instance, societal and cultural factors, such as gender roles and
stereotypes, may have influenced the development of intellectual ability, and discrimination and
bias can act as barriers to education and career advancement. This available research does not
support the belief that men are inherently more intelligent than women. While there was a small
difference, statistically this difference was not significant and this is not large enough to have
practical significance in most real-world situations. This finding generally aligns with previous
research studies that have also indicated minimal or negligible gender differences in intelligence.
The implication is that there is no inherent superiority or inferiority in intelligence between males
and females. Future researchers can build upon this finding by exploring the underlying societal
and cultural factors that may influence the development of intellectual abilities
Result reveals that there is a difference in the average intelligence of persons between age 10-20,
21-30, 31-40 and 40 above. It showed that persons aged 20-30 and 10-20 had the highest intelligence
on the average compared to persons aged 31 and above. Result shows that this difference is
statistically significant. This result is in tandem with the research findings of Salthouse (2010). The
result showed that performance on measures of fluid intelligence peaked at around the age of 20
and declined steadily. Same with that of Hedden and Gabrieli (2004) who found that performance
on measures of cognitive function tended to decline with age that is after reaching its peak,
intellectual ability tends to decline slightly in the later years of life. Other researches evidences also
show that intellectual or cognitive abilities differ and declines with age (Cockburn & Smith, 1991;
Gow, 2016; Hedden & Gabrieli, 2004; Park & Reuter-Lorenz, 2009; Schaie, 1996; Salthouse, 2010;
Salthouse, 2010; Wilson et al., 2002). One reason for this could be due to the decline in the brain’s
ability to generate new neurons and also possible psychological make up of individuals
The influential difference for persons aged 10-30 having the highest intellectual ability may be
attributed to the fact that intellectual ability tends to increase during childhood and adolescence,
reaching a peak in the late teenage years or early 20s. This pattern is thought to be due to the
ongoing development of the brain, which continues to grow and change throughout the lifespan.
While the decline in intellectual ability or intelligence may be due to the gradual loss of neurons
and the decline in the brain's ability to regenerate new neurons as we age. The rate of decline in
intellectual ability is not the same for all individuals. Some individuals may experience a more
pronounced decline in cognitive function in their later years, while others may not experience a
decline at all. There is significant variability in the rate of intellectual development and in the age
at which individuals reach their peak of intellectual ability. However, this difference can also be
due to other factors like educational level, socio-economic status, personality and other
environmental variables. Basically, this finding is consistent with prior research showing a peak in
cognitive abilities during the late teenage years or early 20s, followed by a gradual decline. The
implication is that intellectual ability varies with age, with a decline typically observed in later
years. Future researchers can further investigate the factors contributing to this age-related
difference, such as brain development, the influence of socio-economic status, personality, and
other environmental variables.
Result shows that educational level of persons with SSC, B.Sc. and Ph.D. differ in terms of their
intellectual ability, although the difference was not significant. One possible explanation for the
influence of education level on intellectual ability could be that education exposes individuals to a
wide range of stimuli and challenges that stimulate the brain and promote cognitive development.
Through interactions with teachers and peers, and exposure to diverse ideas and concepts,
individuals are able to develop higher-order thinking skills and knowledge that are essential for
intellectual ability. This result finding is somewhat in line with the result of past researchers in that
education was seen to have an influence on intelligence (Ceci, 1991; Clouston et al., 2012; Deary et
al., 2007; Dole et al., 1991; Furnham & Cheng, 2017; Hegelund et al., 2018; Halpern, 1998;
Hegelund, et al., 2020; Jensen, 1998; Roth et al., 2015; Strenze, 2007). The difference between these
researches and this current study is that no significant influence was found. The difference in these
results could be in the test used in measuring the intelligence of the respondents, and other
demographic variables like location as while this study was conducted in Nigeria in Africa, other
studies were conducted mostly in western countries. Already, previous research has suggested a
link between education and intelligence, with education providing exposure to various stimuli that
stimulate cognitive development. However, the lack of a significant influence in this study
suggests that other factors or test measures may have contributed to the result. Researches in
future can explore the specific aspects of education that may influence cognitive development and
intelligence, taking into account factors such as teaching methods, exposure to diverse ideas and
concepts, and the impact of educational systems in different cultural contexts.
Result shows that the difference in the average intelligence scores of minority and majority
ethnic groups in Port Harcourt metropolis is differs and is statistically significant. This is in syn
with other research findings where different intelligence scores were obtained for persons from
different ethnicity from around the world and Sub-Sahara Africa (Glewwe & Jacoby 1992; Grieve
& Viljoen 2000; Jensen, 1998; Rushton, & Jensen, 2005; Lynn, 1991; Lynn & Vanhanen, 2002; Owen
1992; Rushton, 2000; Rushton & Skuy, 2000; Rushton & Jensen, 2005; Sternberg et al., 2001; Skuy et
al., 2001, 2002; Zaaiman et al., 2001; Zindi, 1994). This observed small differences may be
influenced or due to a variety of factors such as access to education and socio-economic status,
gender, nutrition, cultural experiences and backgrounds such as cultural values and beliefs about
the importance of intellectual development. This finding generally aligns with previous research
studies that have reported variations in intelligence scores across different ethnic groups
worldwide. The implication is that factors such as access to education, socio-economic status,
cultural experiences, and beliefs may contribute to these observed differences. Further research
could delve into the complex interplay between ethnicity, education, socio-economic status, and
cultural experiences to better understand these differences.
Results shows that there is an interaction in the average IQ scores of persons that are, male and
female between age 10-20, 21-30, 31-40 and 40 above and this difference is statistically not
significant. It shows also that there is an interaction in the average IQ scores of persons that are,
male and female from SSCE, B.Scs. and Ph.D. educational level and this difference is statistically
not significant. Result shows also that there is a significant two-way interaction in the average IQ
scores of persons between age 10-20, 21-30, 31-40 and 40 above with SSCE, B.Scs. and Ph.D.
educational level. Result shows that there is a three-way interaction between the average IQ scores
of male and female ages 10-20, 21-30, 31-40 and 40 above with SSC, B.Scs. and Ph.D. educational
level. That is, there is a difference observed from male and female with SSC, B.Scs. and Ph.D.
educational level for persons between age 10-20, 21-30, 31-40 and 40 above; Although the
interaction influence is not significant. The inference from the above is that age gender,
educational qualification on interaction, influence intelligence, however this interaction influence
is not significant. This finding is somewhat in line with the position of researchers who posits that
intelligence is influenced by a variety of factors like gender, educational attainment and age and
other environmental factors. Although, these researchers did not clearly study these variables
studied in this research together, neither did they indicate if a significant interaction was found or
not (Davies et al., 2005; Hyde, 1999, 2014; Park & Reuter-Lorenz, 2009). This result aligns with
existing research that acknowledges the influence of gender, age, educational attainment, and
other environmental factors on intelligence. Future research could explore these variables in more
depth and examine significant interactions, if any, among them.
5. Conclusion
In conclusion, intellectual ability is a complex trait that is influenced by a variety of factors,
including gender, age, ethnicity, and education. While these factors have been seen to influence
intellectual ability, they should not be used to stereotype or make assumptions about individuals.
It is important to recognize that intellectual ability is not fixed, and that individuals have the
potential to develop and improve their cognitive skills throughout their lives.
That is whilst, this study has provided evidence that there is evidence that gender, age,
ethnicity, and education influence intellectual ability and intelligence, it is important to recognize
that intelligence is a multifaceted trait that is influenced by a variety of other factors. It is also
important to approach research on this topic with caution, as it has the potential to be misused and
to reinforce harmful stereotypes.
6. Implications and Recommendation
The implication of the study is that gender does not significantly impact intelligence, challenging
the belief of inherent superiority or inferiority. It implies also that Intelligence tends to peak in
early adulthood and decline with age. and that education alone does not have a significant
influence on intelligence. Furthermore, ethnicity is implicated in variations in intelligence scores.
There are interaction effects among gender, age, and education on intelligence, although not
statistically significant. The study generally implies that multiple factors, such as gender, age,
education, and ethnicity, may play a role in shaping intelligence, but their direct influence is not
substantial or statistically significant.
The findings of this study have important implications for education policy and practice. Based
on findings, it is recommended that since education and age influence intellectual ability, investing
in education, particularly in the early years, can have lasting benefits for the cognitive
development and intellectual ability of individuals for both male and female alike.
7. Limitation and Suggestion for Further Study

Although, the research was able to achieve its aim, the research is limited by not using a larger
sample size from a more diverse geographical location. Although the following limitations
notwithstanding, a representative sample was obtained and the findings were not affected and
thus valid generalization is enabled.
It is suggested that future research in this area should continue to examine the role of genetics,
education, and other psychological factors like personality in any observed differences in
intellectual ability between men and women. It will also be important to study the impact of
societal and cultural factors on intelligence and performance, and to identify ways to reduce the
influence of discrimination and bias.
Author contributions: All authors have sufficiently contributed to the study, and agreed with the
conclusions.
Declaration of interest: No conflict of interest is declared by authors.
Funding: No funding source is reported for this study.
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Journal of Pedagogical Research

Volume 7, Issue 4, 2023

Keywords: Intellectual ability; Gender; Age; Education; Ethnicity

Address of Corresponding Author

Intellectual ability or intelligence is typically measured through intelligence tests. There is a

1.4. Ethnicity and Intellectual Ability

7. Limitation and Suggestion for Further Study

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