Showing posts with label gender. Show all posts
Showing posts with label gender. Show all posts

Friday, January 27, 2012

Monday, October 10, 2011

Research byte: Cognitive gender differences as measured by the DAS-II

Another strong methodological article by Keith and Reynolds research team, this one adding to the IQ gender difference research knowledge via analysis if the DAS-II. Double click on images to enlarge
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Monday, June 13, 2011

Research brief: Gender differences in intelligence on the WAIS-III (Irwing, in press)




There has been no shortage of contemporary research on gender differences in cognitive abilities (click here for prior IQs Corner posts), and g (general intelligence) in particular. Irwing has a new article "in press" that contributes to this literature, both by reinforcing some prior findings...but also being at variance with other. The introduction provides a nice brief overview of some of the reasons (primarily methodological) for difference on the male-female g-difference research.

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Tuesday, January 13, 2009

Saturday, December 06, 2008

CHC intelligence gender differences manuscript


[double click image to enlarge]

A CHC gender difference manuscript by Keith et al. (2008), published in Intelligence, was previously featured at this blog as "in press." The publication is now formal. Kudos to Tim Keith et al. Click here to see prior comments and post re: this research

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Monday, February 25, 2008

Sex differences in IQ: Important new research

Damn!.......this is an exciting time us who are interested in the psychology of human intelligence. Psychometric research has largely converged on the Cattell-Horn-Carroll (CHC) theory of cognitive abilities (aka, Gf-Gc theory) as the most well-validated structure of human cognitive abilities. New and old intelligence batteries are being revised to fit the CHC model (KABC-II; Stanford-Binet V; WJ-R/WJ III). Within this context additional excitement has been building re: a number of long-standing group intelligence difference research controversies (racial differences; gender differences) that are enjoying a resurgence among individual difference researchers.

It is within this context that I just read the excellent "in press" article (journal of Intelligence) by my friend Dr. Tim "Happiness is a latent variable" Keith (and his band of top notch SEM'ers) that addresses gender differences in latent variable CHC cognitive abilities and general intelligence (g). A copy of the article can be viewed by clicking here. The abstract of the article is reproduced below.

As per usual, I'm extremely impressed with the methodological rigor of Tim's research. Not only does he present his sophisticated CHC SEM-based research with clarity and statistical elegance, he addresses potential methodological criticisms via additional post-hoc analysis...to help sort out why some of his findings are at variance with recent gender difference research by such heavy hitters as Richard Lynn (click here for his official web page).

I think this is a very important article for a number of reasons. First, it examines gender differences in cognitive abilities as per the CHC taxonomic framework. Second, Keith et al. focus on the analysis of latent CHC constructs and not constructs measured with imperfect manifest variable composite variables (this distinction is discussed in detail in the article). Third, Keith et al.'s research uses a battery of tests (WJ III battery) that were specifically designed as per the CHC theory and, John Horn and Jack Carroll both served as consultants on the WJ III [conflict of interest note - I'm a coauthor of the WJ III and thus have a financial interest in the instrument]. Finally, given the wide age-range of the WJ III battery, analysis was possible across almost the complete age-range of development with a common set of CHC-validated indicators.

The major findings are summarized in the abstract below. The finding that is likely to be most controversial is the that males and females did not differ in general intelligence (g) during childhood (consistent with most research), but that females displayed statistically significantly higher g at adulthood (18 years and above). This female g advantage is at variance with Richard Lynn's developmental hypothesis-based research that has suggested that males show statistically higher g at adulthood. My guess is that these divergent findings are going to enjoy some stimulating scholarly debates. Keith's discussion of the potential reasons for these divergent findings is, IMHO, very well thought out and buttressed by his secondary post-hoc analysis focused on potential methodological differences between the two sets of research.

Wouldn't it be great if Lynn and Keith could present and debate their respective findings at a future ISIR conference?

My only minor quibble with the article is that Keith et al. labeled their two-test combination of the WJ III Visual-Auditory Learning and Memory-for Names tests as a broad Glr latent factor (long-term storage and retrieval). As I've written many places over the past few years, and as espoused by CHC cross-battery research, these two tests are best viewed as slightly different indicators of the narrow Glr ability of Associative Memory (MA). Glr is broader than just MA. I would suggest that the Glr findings be more narrowly interpreted as providing information on gender differences in the narrow MA ability...and cannot be generalized (just yet) to the broad domain of Glr (click here for page that defines and lists the breadth of narrow abilities under Glr).

Abstract

  • Sex differences in the latent general and broad cognitive abilities underlying theWoodcock–Johnson Tests of Cognitive Abilities were investigated for children, youth, and adults ages 6 through 59. A developmental, multiple indicator–multiple cause, structural equation model was used to investigate sex differences in latent cognitive abilities as well as developmental changes in these differences across the 6 to 59 age span. Females showed a consistent advantage on the latent processing speed (Gs) factor, and males showed a small, consistent advantage on the latent comprehension–knowledge (Gc) factor. Males also showed an advantage on latent quantitative reasoning (RQ) and visual–spatial ability (Gv) factors at most ages, although the latter was statistically significant only for adults. No statistically significant sex differences were shown on latent auditory processing, short-term memory, long-term retrieval, or fluid reasoning factors. The higher-order, latent g factor showed inconsistent differences for children, small, nonsignificant differences favoring females for adolescents, and fairly consistent statistically significant differences favoring females in adulthood. Findings are inconsistent with developmental theory that suggests males should show an advantage on g in adulthood. Supplemental analyses suggested that methodological choices, including the use of latent variables versus composites and methods for dealing with missing data, can affect research findings.
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Monday, October 08, 2007

Video games narrow visual-spatial (Gv) gender gap

Thanks to the ENL blog for drawing our attention to a new article in one of my favorite journals (Psychological Science) that suggests that playing today's video games may help reduce probably the most significant remaining gender difference in cognitive abilities...namely...visual-spatial abilities, especially visual rotation (Gv-SR; Vz)

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Monday, January 15, 2007

Spatial visualization rotation strategy and gender differences


Of all the gender difference research that has focused on human cognitive abilities, one of the most robust differences remaining is in the domain of spatial visualization/mental rotation (Gv:Vz-Visualization).

Within the past few weeks I stumbled across two articles that shed light on possible reasons for gender differences in Gv:Vz. I find this research of particular interest given that I was the member of the WJ III test development team that developed the WJ III Diagnostic Supplement Block Rotation test, which is modeled on the classic Vandenberg Mental Rotations Test

Below are the article references, abstracts and pdf links. The bottom line conclusion from these studies is that a major portion of the difference in male/female performance on mental visual rotation tasks may be due to differences in (a) spatial working memory, and/or (b) the use of different cognitive strategies when approaching the tasks.

Regarding the strategy differences, the Geiser et al. study reinforces what I have heard from clinicians. Apparently some individuals use direct mental rotation strategies (which is the more "pure" mental visualization rotation strategy), others use an analytic feature comparison strategy (more often females), and some folks, typically those that do the best on these type of tasks, flexibly move between both types of strategies. The direct mental rotation strategy is the essence of spatial visualization/rotation ability.

These findings should remind those of us interested in the measurement of cognitive abilities that the primary factor analysis based interpretation for the lion's share of the variance for a specific task (in this case, spatial visualization-Gv:Vz) is based on group statistics...and likely represents the primary interpretation for performance on the measure. However, as all astute intelligence test clinicians know, some individuals often "turn the tables" on the presented task and change the nature of the abilities measured.


Geiser, C., Lehmnann, W. & Eid, M. (2006). Separating “Rotators” From “Nonrotators” in the Mental Rotations Test: A Multigroup Latent Class Analysis. Multivariate Behavioral Research, 41(3), 261–293 (click here to view)

Abstract
  • Items of mental rotation tests can not only be solved by mental rotation but also by other solution strategies. A multigroup latent class analysis of 24 items of the Mental Rotations Test (MRT) was conducted in a sample of 1,695 German pupils and students to find out how many solution strategies can be identified for the items of this test. The results showed that five subgroups (latent classes) can be distinguished. Although three of the subgroups differ mainly in the number of items reached, one class shows are very low performance. In another class, a special solution strategy is used. This strategy seems to involve analytic rather than mental rotation processes and is efficient only for a specialMRT item type, indicating that not all MRT items require a mental rotation approach. In addition, the multigroup analysis revealed significant sex differences with respect to the class assignment, confirming prior findings that on average male participants perform mental rotation tasks faster and better than female participants. Females were also overrepresented in the analytic strategy class. The results are discussed with respect to psychometric and substantive implications, and suggestions for the optimization of the MRT items are provided.

Kaufman, S. (in press). Sex differences in mental rotation and spatial visualization ability: Can they be accounted for by differences in working memory capacity? Intelligence. (click here to view)

Abstract
  • Sex differences in spatial ability are well documented, but poorly understood. In order to see whether working memory is an important factor in these differences, 50 males and 50 females performed tests of three-dimensional mental rotation and spatial visualization, along with tests of spatial and verbal working memory. Substantial differences were found on all spatial ability and spatial working memory tests (that included both a spatial and verbal processing component). No significant differences were found in spatial short-term memory or verbal working memory. In addition, spatial working memory completely mediated the relationship between sex and spatial ability, but there was also a direct effect of sex on the unique variance in three-dimensional rotation ability, and this effect was not mediated by spatial working memory. Results are discussed in the context of research on working memory and intelligence in general, and sex differences in spatial ability more specifically.

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Wednesday, November 22, 2006

Do the sexes use different brain areas when "planning"?

Mixing Memory has a VERY interesting post regarding recent studies of possible gender differences in "planning" ability (part of executive functioning), as measured by the classic Tower of London task. MM's post speaks for itself. Of particular interest are findings suggesting no manifest performance difference between genders, BUT, significant differences in the areas of the brain's used (based on fMRI analyses). Check it out

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Friday, October 20, 2006

Neuroscienjce of learning (brain-based learning): Posts moving to The IQ Brain Clock

Yesterday's posts (click here, here) dealing with facts and fictions regarding brain-based learning in education, plus the response of SharpBrains, set me off digging through my electronic library of professional articles...in search of articles on the use of neuroscience in learning in education. I found a number of good overview articles that I will comment and post shortly.

However, it dawned on me that this line of research is probably more consistent with the focus of my new blog (Tick Tock Talk: The IQ Brain Clock). Thus, this note is to inform regular IQs Corner readers that I'm going to start shifting posts focused on the neuroscience of learning over to The IQ Brain Clock Blog. I will likely also broaden the definition and purpose of that blog.

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Sunday, July 23, 2006

Gender differences in IQ - are boys more variable in intelligence?

There is little doubt that the long history of research on racial and gender differences in intelligence has been controversial. Interestingly, there has been a recent upswing in recent studies in both domains (click here, here, here , here, here, here here, here, here, and here, for a sampling of some prior gender/IQ posts on this blog).

Most of the research that has captured the attention of both researchers and the popular press have focused on mean (average) IQ score differences. Less attention has focused on possible differences in the range/variability of intelligence differences by race or sex. Arden and Plomin address this issue in a recently published study of the differences in the variability of intelligence scores (particuarly at the high and low ends of the IQ distributions) in a large British sample. The article, including a link to a pdf copy, is listed below along with the abstract and some select comments by the authors.

  • Arden, R. & Plomin, R. (2006). Sex differences in variance of intelligence across childhood. Personality and Individual Differences 41, 39–48. [click here to view article]

Abstract

  • Why are males over-represented at the upper extremes of intelligence? One possibility for which there is some empirical support is that variance is greater among adult males. There is little published evidence of the development of that variability – is it manifest in early childhood or does it develop later? We explored sex differences in phenotypic variance in scores on a general ability factor extracted from several tests of verbal and non-verbal ability at ages 2, 3, 4, 7, 9 and 10 (Ns from >10,000 to >2000) in a sample of British children. We found greater variance, by Levene’s test of homogeneity of variance, among boys at every age except age two despite the girls’ mean advantage from ages two to seven. Girls are signi?cantly over-represented, as measured by chi-square tests, at the high tail and boys at the low tail at ages 2, 3 and 4. By age 10 the boys have a higher mean, greater variance and are over-represented in the high tail. Sex di?erences in variance emerge early – even before pre-school – suggesting that they are not determined by educational influences. This large sample indicates that boys and girls follow sex-specifc developmental pathways. It is a commonplace within mothers’ groups that girls’ mental abilities develop earlier than do those of boys; we have evidence indicating that such anecdotal observations are well founded. Boys seem to ‘get going’ a little later than do girls; the boys in our sample catch up in middle childhood and have nudged ahead of the girls by age 10. This study offers tantalizing evidence of developmental trends in variance dfferences between the sexes.
Why might boys vary more than girls? The authors offer some general genetic and environmental possibilities.
  • Genetic possibilities include not only X-linked genes but alsoautosomal genes that have different ffects in boys and girls. In terms of the sex-limitation model-fitting of quantitative genetics, genetic effects on variance could arise from differences in heritability (the same genes can affect boys and girls differently) or differences in genetic correlation(different genes might affect boys and girls). These genetic differences could be the result of different selective forces having acted ancestrally on g in males and females.
  • There are also several environmental possibilities, although social forces such as differential parenting or schooling are a more plausible source of means differences than variance differences. A variance difference in the absence of a means dfference, as we found during the pre-school years of 3 and 4, then again at age 7 is di?cult to explain by socialization though we cannot exclude this possibility. A socialization hypothesis would predict that variability would increase or decrease in males and females under different cultural and temporal contexts.
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Wednesday, July 19, 2006

Saturday, April 29, 2006

Are boys at an eductional disadvantage due to slower cognitive processing speed? New Intelligence research article

Interesting article in the journal Intelligence, based on analysis of the, WJ (1977), WJ-R (1989) and WJ III (2001) nationally representative norm samples, that suggests that males may be at a disadvantage in learning due to generally slower cognitive processing speed (Gs as per CHC theory) than females. Given my WJ III authorship status (and potential conflict of interest), I'm only posting the reference, abstract, one summary comment from the article, and a URL link (so readers can read and form their own conclusions).

The important question from this study, which I hope stimulates some comments at this blog and/or discussion over on the CHC listserv, is "what are the educational implications of this finding?"
  • Camarata, S. & Woodcock, R. (2006). Sex differences in processing speed: Developmental effects in males and females. Intelligence, 34, 231-252. (click here to view)
Abstract
  • The purpose of this study was to compare the cognitive abilities and selected achievement performance of females and males across the lifespan on standardization samples of broad cognitive abilities in 1987 participants (1102 females, 885 males) from the WJ III, 4253 participants (2014 males, 2239 females) from the WJ-R, and 4225 participants (1964 males and 2261 females) from the WJ-77. Preschool through adult cohorts were included in the analyses. The results indicated that males scored significantly lower on estimates of Gs (processing speed) in all three normative samples, with the largest difference evident in adolescent subgroups. A secondary finding was significantly higher scores for males on estimates of comprehension knowledge (Gc) in all three samples. Follow-up analyses of the achievement tests also indicated lower performance for males on speeded tests such as reading fluency and writing fluency. There was a high degree of concordance across tests and no sex difference was observed in overall estimates of general intellectual ability (GIA) on the WJ III. The educational implications of these findings are discussed with an emphasis on the adolescent (high school) cohort.
Additional comment from authors regarding potential educational implications:
  • "...reading and writing fluency were significantly lower in males in the data from achievement testing, a difference that is likely related, at least in part, to the processing speed difference. Consider that many classroom activities, including testing, are directly or indirectly related to processing speed. The higher performance in females may contribute to a classroom culture that favors females, not because of teacher bias Hoff-Sommers, 1998) but because of inherent sex differences in processing speed and the relationship this parameter has with classroom activities and potential learning differences in males and females."
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Sunday, January 22, 2006

Gf (fluid intelligence) gender difference research--NNAT test study

The following article, which is "in press" in Intelligence, reports (in very large samples) no "practically" significant gender differences (from ages 5-17) in Gf (fluid intellignece) as measured by a matrices battery. Readers should digest this article in the context of other recent (and controversial) research re: IQ-gender differences research.

Rojahn, J. & Naglieri, J (in press). Developmental gender differences on the Naglieri Nonverbal Ability Test in a nationally normed sample of 5–17 year olds. Intelligence.

Abstract
  • Lynn [Lynn, R. (2002). Sex differences on the progressive matrices among 15–16 year olds: some data from South Africa. Personality and Individual Differences 33, 669–673.] proposed that biologically based developmental sex differences produce different IQ trajectories across childhood and adolescence. To test this theory we analyzed the Naglieri Nonverbal Ability Test (NNA; [Naglieri, J. A. (1997). Naglieri Nonverbal Ability Test-Multilevel Form. San Antonio: Harcourt Assessment Company.]) standardization sample of 79,780 children and adolescents in grades K-12, which was representative of the US census on several critical demographic variables. NNAT data were consistent with Lynn’s developmental theory of gender differences insofar as (a) there were no gender differences between 6 and 9 years; (b) females scored slightly higher between 10 and 13 years; and (c) males were ahead of females between the ages of 15 and 16. However, the discrepancies between the genders were smaller than predicted by Lynn. In fact they were so small that they have little or no practical importance. In other words, the NNAT did not reveal meaningful gender differences at any stage between the ages of 6 and 17 years.
To read article......

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Monday, November 21, 2005

Gender brain differences in spatial (Gv) navigation

A post (and link to the journal article) at the Eide Neurolearning blog re: an fMRI study of gender differences in spatial (Gv) navigation.

Keywords: fMRI Gv visual-spatial gender [Note...I'm going to start adding keywords to posts so I can more readily build topic index URL links at the home page of this blog]