Lupine Publishers | Scholarly Journal Of Psychology And Behavioral Sciences
Introduction
For
the last century it has been asserted by numerous scholars that males and
females have the same average intelligence, e.g., Halpern [1]: “Females and
males score identically on IQ tests”, [2] and “When it comes to intelligence,
it has been convincingly established that there are no differences between the
average woman and man”, and [3-8]. This consensus has been disputed [8-11]. And
who has advanced the developmental theory of sex differences in intelligence
that maintains that while there is no sex difference in young children and
early adolescence, males begin to obtain higher average IQs than females in
mid-adolescence increasing to 4-5 IQ points among adults. Some evidence for
this theory has been provided [11,12]. The present paper examines these two
theories with some Wechsler data in Taiwan.
Methods
The
data to be presented are for sex differences in intelligence in the Taiwan
standardization samples of the Wechsler Preschool and Primary Scale of
Intelligence-Fourth Edition (WPPSI-IV) for 2.5-7-year-olds and of the Wechsler
Adult Intelligence Scale-Fourth Edition (WAIS-IV) for adults aged 16-74 years.
The Wechsler Preschool and Primary Scale of Intelligence-Fourth Edition
(WPPSIIV) was standardized in Taiwan in 2012. The standardization sample
consisted of 924 children (52.1 percent boys, 47.9 percent girls) aged from
2.5-7 years and was drawn from the north, central, east and south geographical
regions with parents’ education level percentages matched to those of the
population given in the most recent census [13]. The structure of the Taiwan
WPPSI-IV is the same as the American WPPSI-IV in consisting of 15 tests given
in Table 1 that are scored to give the Full-Scale IQ, Verbal Comprehension
Index, Visual Spatial Index, Fluid Reasoning Index, Working Memory Index and
Processing Speed Index. The Wechsler Adult Intelligence Scale IV (WAIS-IV) was
standardised in Taiwan between July 2015 and January 2016. The standardisation
sample consisted of 1105 individuals (49.6 percent males, 50.4 percent females)
aged from 16 to 90 years and was drawn from the north, central, east and south
geographical regions with percentages matched to those of the populations given
in the most recent census. In order to control for the educational level in
males and females, the data of older adults aged 75 to 90 (N=251) were not
used. This study used only the data of 850 adults aged 16 to 74 for whom the
proportion of males and females at each education level is the same in (χ2
=4.39, df=4, p=.35). The structure of the Taiwan WAIS-IV Wechsler is the same
as the American WAIS-IV in consisting of 15 tests that are scored to give the
Full-Scale IQ, the Verbal Comprehension Index, Perceptual Reasoning Index,
Working Memory Index and Processing Speed Index. Notice that the WAIS-IV
maintained the four-factor structure while the WPPSI-IV provided the updated
five-factor structure. The WAIS-IV Perceptual Reasoning Index was divided into
two WPPSIIV indices, Visual Spatial Index and Fluid Reasoning Index, thus the
constructs of Perceptual Reasoning Index covers the constructs of both Visual
Spatial and Fluid Reasoning Indices.
Results
The
results are given in Table 1. This shows, reading from left to right, the IQs
and subtests, the sex differences on the WPPSIIV expressed as d (the difference
between the male mean-female mean divided by the pooled SD), the t values for
the statistical significance of the sex differences, the sex differences on the
WAISIV expressed as d, and the t values for the statistical significance of the
sex differences.
Table 1: Sex differences
on the WPPSI-IV and WAIS-IV in Taiwan.
Discussion
There
are nine points of interest in the results. First, there was virtually no sex
difference (.05d) on the Full-Scale IQ on the WPPSIIV but on the WAIS-IV males
obtained a statistically significant (p<.001) higher Full-Scale IQ (.27d),
equivalent to 4.05 IQ points. These results therefore confirm the developmental
theory of sex differences in intelligence that among adults’ males have a
higher average IQ than females of between 4-5 points. Second, males obtained
statistically significant (p<.001) higher IQs of approximately the same
magnitude on the WAIS-IV on the Verbal Comprehension Index (.27d), the
Perceptual Reasoning Index (.37d) (including both Visual Spatial and Fluid
Reasoning components) and the Working Memory Index (.25d). Third, on the
Processing Speed Index females obtained a negligibly higher IQ of .05 on the
WPPSI-IV and a statistically significant (p<.05) higher IQ (.14) on the
WAIS-IV. Fourth, on the Similarities subtest there is virtually no sex
difference (.04d) on the WPPSI-IV but males obtained a statistically
significant (p<.01) higher score (.18d) on the WAIS-IV. These differences
are closely similar to those of .05d and .27d on the Full- Scale IQ. This is
predictable because this subtest poses questions like “In what way are work and
play alike?” and “In what way are an enemy and a friend alike?” and measures
verbal reasoning. The present results confirm the increase in verbal reasoning
in males from .15d in 14-year-olds to .25d in 18-year-olds in the British
standardization sample of the DAT (Differential Aptitude Test [14] and the
higher verbal reasoning score .17d obtained by males in a Spanish sample of
23-year-old applicants to a university [8]. Fifth, on the Information subtest
males obtained a significantly higher score of .17d in the WPPSI-IV and of .44d
in the WAIS-IV. These results confirm numerous studies showing that males have
more general knowledge than females [14-16]. The present results show that this
advantage is present in 2–7-year-olds and increases with age. Sixth, on the
Vocabulary subtest males obtained a higher score than females in the WPPSI of
.31d in the WAIS of .09d. This is the only test in which males obtained a
higher score than females on the WPPSI than on the WAIS [17]. On the Picture
Naming subtest males obtained a higher score than females in the WPPSI of .21d.
Picture Naming is a test of vocabulary in which the examiner points to a
picture and asks What is this? This test is not present in the WAIS [18-25].
The higher scores obtained by males on the two vocabulary subtests in the WPPSI
are unusual. Most studies have reported virtually zero sex differences in
vocabulary. Hyde & Linn’s meta-analysis of 40 American studies gave a
female advantage of .02d, a subsequent American study by Salthouse (2004) gave
a male advantage of .03d derived as the average of 33 studies of samples aged
from 19 to 95 years, and a more recent study by Hyde gave a female advantage of
.02d. The absence of a sex difference in vocabulary has been reported in the
United Kingdom in the standardization samples of the Mill Hill Vocabulary Scale
(mean age 12.5 years, d = 0.0; [17]) and in a further sample on the Mill Hill
Vocabulary Scale (mean age 10.5 years, d = 0.0; [18]).
But
a few studies have reported higher scores by males on vocabulary. A small male
advantage has been reported in England in a sample on the Mill Hill Vocabulary
Scale (n = 2000, mean age 9 years, d = .10; [23]) and in Belgium on the Boston
Naming Test (n = 371, mean age 9 years, d = .08; Storms, Saerens & De
Deyn). The only study to report a male advantage of about the same magnitude as
those in the present results is Tombaugh & Hubley’s in the norms for adults
aged 25 to 88 years on the Boston Naming Test (n = 210; .26d). Seventh, on the
Comprehension subtest males obtained a significantly higher score than females
in the WPPSI of .21d and in the WAIS of .21d (p<.01) [24-27]. In this
subtest, the examinee is required to answer questions based on his/her understanding
of general principles and social situations. The male advantage is much greater
than that in the United States where Schaie (2005, p. 102) reported a male
advantage of .07d in verbal comprehension in 4850 American adults aged 25 to
81, Keith, Reynolds, Patel & Ridley, (2008) reported a male advantage of
.07d in a sample of 6 through 59 year olds (n = 6970) on the latent
comprehension– knowledge (Gc) factor in the Woodcock–Johnson Tests of Cognitive
Abilities III, and Reynolds, Keith, Ridley & Patel (2008) reported a male
advantage of .07d in a sample of 6 through 18 year old (n = 2375) on verbal
knowledge in the Kaufman Assessment Battery for Children [28-30]. Eighth, on
the Block Design subtest there is virtually no sex difference (.10d) on the WPPSI-IV
but males obtained a statistically significant (p<.001) higher score (.40d)
on the WAIS-IV. This subtest measures spatial ability and the higher score of
adult males in the WAIS-IV confirms the meta-analysis of sex differences in
spatial abilities adults in the United States [31- 33] and that concluded that
there is male advantage of .50d, the later meta-analysis [34-37] who gave the
male advantage as .445d, and the more recent meta-analysis Archer [38] and who
gives the male advantage as .46d. Ninth, on the three Processing Speed
subtests, there were no significant sex differences on the WPPSIIV but females
obtained a statistically significant (p<.05) higher score (.18d) on Coding
in the WAIS-IV. The higher score obtained by females is consistent with that in
the standardisation samples of the WAIS-IV in South Korea of .38d [39,40]. The
authors assert that all procedures contributing to this work comply with the
ethical standards of the relevant national and institutional committees on
human experimentation and with the Helsinki Declaration of 1975, as revised in
2008 [41,42].
https://lupinepublishers.com/psychology-behavioral-science-journal/pdf/SJPBS.MS.ID.000198.pdf
For more Lupine Publishers Open Access Journals Please visit our website: https://lupinepublishersgroup.com/
For more Psychology And Behavioral Sciences Please Click
Here: https://lupinepublishers.com/psychology-behavioral-science-journal/
To Know more Open Access Publishers Click on Lupine Publishers
Follow on Linkedin : https://www.linkedin.com/company/lupinepublishers
Follow on Twitter : https://twitter.com/lupine_online
No comments:
Post a Comment