Thursday, May 31, 2007

Processing speed (Gs) and working memory (Gsm-MW) - more support for developmental cascade hypothesis

For a number of years I've been intrigued by the empirical research that has investigated the "developmental cascade" model. This model hypothesizes that developmental increases in processing speed (Gs) results in increases in working memory abilities (Gsm-MW), which in turn has a large and direct effect on fluid reasoning (Gf) and possibly general intelligence (g).

The first I read of the developmental cascade hypothesis was a 1996 article by Fry and Hale in Psychological Science. Subsequently, I provided an overview of this research literature in my chapter in the 2005 Flanagan and Harrison Contemporary Intellectual Assessment book.My overview also included the presentation of causal models I ran that provided, IMHO, strong support for this theoretical conceptualization of cognitive growth.

A new study by Kail directly investigates Fry and Hale's developmental cascade hypotheses with a longitudinal study design. Kail's research continues to support this model and can be viewed by clicking here.

Regular readers of this blog know that I've been very interested in research regarding the role of working memory in academic and cognitive performance. Click here to view all posts to date that have dealt with working memory, cognitive load, etc.

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Random tidbits from the mind blogsphere - 5-31-07

  • Check out the Brain Injury blog for a post regarding a possible link between Parkinson's disease and head trauma.
  • Thanks again to the great DI blog for a post regarding the neural substrates of symbol use
  • ENL blog has an interesting post on how video game training may increase visual span
  • Thanks to Mind Hacks for the FYI re: a New York Times book review of a new book on neuroplasticity - the brain's ability to re-organize itself after neurological insult/brain injury.
  • More on new books. The Neuroethics and Law Blog reports information regarding a new book (Intervening in the brain) on the emerging ethical issues surrounding our increased intervention in the brain via neurotechnology.
  • Omni Brain highlights a recent study dealing with the impact of training executive function abilities in young children.

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The man who only loved numbers - Paul Erdos

In Joel Schneider's prior post, he makes a reference to a statement by Paul Erdos. This reminded me of the book I read about this amazing (and eccentric) mathematician. I thoroughly enjoyed reading this book (The man who only loved numbers) a number of years ago and recommend the book to readers of this blog.  Additional information re: the book can be found by clicking here.

Can disabling a gene make you smarter - Joel Schneider guest post

The following is a guest blog post by Joel Schneider (Clinical psychologist, Illinois State University), a member of IQs Corner Virtual Community of Scholars project.

Can Disabling a Gene Make You Smarter?

Try answering this analogy: Athletes are to Steroids as Scholars are to ___________.

Erdos’s joke that mathematicians are machines that turn coffee into theorems notwithstanding, there is no really good answer to this question. That may change in the near future, however. Soon we may be faced with a deluge of drugs and genetic procedures that enhance cognitive functioning.

A new study to be published in Nature Neuroscience was released recently may be a harbinger of things to come. The researchers disabled a gene in mice and the mice with the disabled gene performed better than the control group on a variety of cognitive tasks like navigating mazes and remembering how to avoid shocks. The gene in question codes for an enzyme that is implicated in Alzheimer’s dementia.

Here is the new twist: the gene was disabled in adult mice and only in the brain! Amazing! If these similar techniques become available for humans, the raging controversies about whether IQ is partly inherited will be moot. Soon envious people will spread rumors about “unnaturally” quicklearners and call them names like “brain-tweakers” and “GENE-iuses.”

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Friday, May 25, 2007

Thursday, May 24, 2007

More on spatial visualization rotation abilities (Gv-Vz)

Either there has been increased research interest in the role of spatial visualization (Gv-Vz) strategies/abilities and cognitive/academic performance as of late, or, I've been selectively attentive to articles that address this topic in my weekly searches of the social and behavioral research literature. Regardless, during the past two weeks I've run across three additional studies that have investigated how individuals approach classic block rotation visualization tasks and/or how these abilities/strategies can be modified via training.

Briefly, "mental rotation refers to the cognitive process of imagining how an object would look if rotated away from the orientation in which it is actually presented" (Jansen-Osmann & Heil, in press)

First, I've previously commented on gender studies that have suggested two differing cognitive strategies that individuals adopt when approachinging visual mental rotation tasks. As summarized in my prior post:
  • "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."
Now, Stieff (2007) has added to this literature vis-a-vis the exploration of the use of these two different strategies in scientific reasoning. Based on three separate investigations, Stieff concluded the following, which they then discuss in terms of practical applications for differential instruction.
  • "In many scientific domains the emphasis on diagrams and external representations of three-dimensional objects suggests a need for students to generate and manipulate internal visuo-spatial representations;however, the use of feature-based strategies can obviate such visualization. The present work suggests that the diverse array of molecular representations available in chemistry and the use of a feature-based analytical strategy for interpreting and analyzing spatial information in external representations allow students and scientists to sometimes avoid mental rotation for problem solving. These results are consistent with similar findings from studies in engineering and design where problem solvers can use unique analytical and visuo-spatial strategies"
Next, Wiedenbauer and Jansen-Osmann (in press) present findings that suggest that it may be possible to improve mental rotation ability in children via manual visualization training. Jansen-Osmann strikes again, this time in association with with Heil (Jansen-Osmann & Heil, in press), in a developmental study of potential qualitative differences between children and adults in rotational uncertainty.

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Nonword (Ga/Gsm) repetition tasks - literature to track

Sorry for my very inconsistent posting over the past few months. This summer has been crazy as I work with my lovely fiance to plan a wedding, sell two houses, and build a new house :)

The purpose of this post is to alert readers to a trend I've detected (I may be late in this least I've now noticed it..better late than never)---an increasing body of empirical literature that implicates the abilities measured by non-word repetition tasks in the identification of children with specific language impairments (SLI). Today I ran across a meta-analysis by Estes et al. (2007; click here to view) that continues to highlight the importance of these abilities and measurement tasks. The abstract is reproduced below.

Something important seems to be measured by non-word repetition tasks, although what these abilities are is a matter of debate. As noted by Estes et al.:
  • "There has been considerable debate surrounding the nature of the skills tapped in nonword repetition, whether it recruits phonological working memory (Bishop et al., 1996; Botting & Conti-Ramsden, 2001; Montgomery, 1995b; Van der Lely & Howard, 1993), phonological encoding (Kamhi & Catts, 1986), phonological awareness or sensitivity (e.g., Metsala, 1999), or a general phonological processing ability (e.g., Bowey, 1996, 2001). Many authors have also acknowledged that the act of repeating nonwords involves multiple processes (e.g., Briscoe, Bishop, & Norbury, 2001; Edwards & Lahey, 1998; Gathercole, Willis, Baddeley, & Emslie, 1994; Snowling, Chiat, & Hulme, 1991). A child's ability to repeat a novel word may be affected by any of the component skills involved in the process of hearing, encoding, and producing a word form: the ability to perceive speech distinctions; the preciseness, robustness, or organization of phonological and morphological representations; the ability to store the word form; and motor planning and articulation skills. The impairments of children with SLI may affect performance at any point or at many points in this process."
I concur. Task analysis suggests that, from a CHC factor analysis perspective, non-word repetition tasks may garner their diagnostic sensitivity from their factorial complexity (i.e., they measure multiple important abilities/constructs). These may include such Ga (auditory processing) narrow abilities as phonetic coding (PC), speech sound discrimination (US), memory for sound patterns (UM), and temporal tracking (UK). In addition, clearly the Gsm narrow ability of working memory (MW; what is often called the phonological working memory or articulatory loop) is implicated. Other CHC candidate abilities included efficacy of accessing a person's lexicon (aka; speed of lexical access or naming facility-Glr: NA). For users of the WJ-III battery [conflict of interest disclosure - I'm a coauthor], we have a test called Sound Awareness that has been found to be very predictive of academic achievement and diagnostic classification (normal vs some kind of disorder)...primarily, I believe, because it is a CHC ability-complex measure of multiple narrow abilities (at a minimum, PC and MW). Measures that are not factorially "pure" can still be important and useful for other assessment purposes - diagnosis and prediction.

I would encourage readers to continue to track the emerging non-word repetition practical and theoretical literature. Another important article to read is by Gathercole (2006). Also, I've previously blogged about a non-word repetition article in the journal Dyslexia that, IMHO, suffered from serious methodological flaws and should not be taken seriously. Finally, as my awareness of this literature has grown I recently ran a search of the IAP Reference Database for other articles that may be related (as you will see..there is no shortage of literature to read in this area).

Estes et al. (2007) Abstract
  • Purpose: This study presents a meta-analysis of the difference in nonword repetition performance between children with and without specific language impairment (SLI). The authors investigated variability in the effect sizes (i.e., the magnitude of the difference between children with and without SLI) across studies and its relation to several factors: type of nonword repetition task, age of SLI sample, and nonword length. Method: The authors searched computerized databases and reference sections and requested unpublished data to find reports of nonword repetition tasks comparing children with and without SLI. Results: Children with SLI exhibited very large impairments in nonword repetition, performing an average (across 23 studies) of 1.27 standard deviations below children without SLI. A moderator analysis revealed that different versions of the nonword repetition task yielded significantly different effect sizes, indicating that the measures are not interchangeable. The second moderator analysis found no association between effect size and the age of children with SLI. Finally, an exploratory meta-analysis found that children with SLI displayed difficulty repeating even short nonwords, with greater difficulty for long nonwords. Conclusions: These findings have potential to affect how nonword repetition tasks are used and interpreted, and suggest several directions for future research.
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Recent literature of interest - 5-14-07

This weeks (actually the last two weeks) recent literature of interest can be found by clicking here.

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Friday, May 18, 2007

Quantitative reasoning-proposed hierarchical structure

[Double click on image to enlarge]

I just ran across an interesting article that proposes a hierarchical substructure to quantitative reasoning (Gf-RQ), based on the work of Klauer. According to the authors, inductive quantitative reasoning is conceptualized to consist of three sub-abilities (similarity, dissimilarity, integration), which in turn, subsume 6 narrower abilities. In the language of CHC theory, this model specifies new sub-stratum abilities below the narrow stratum I abilities. The model is represented in the figure at the top of this post.

The authors gathered data on 135 subjects and fit a 3-level hierarchical model. They used confirmatory factor analysis methods and reported a good model fit. Unfortunately, I see flaws in the analysis. The major flaw is that they fit only one model. No competing models were specified and evaluated. The finding that two of the second-order factors were essentially isomorphic (factor loadings = .99) with the highest order inductive RQ factor suggests that more simple models should have been evaluated. Thus, I would not place major stock in this structural study at this time (I'm not going to run out and suggest revision to the CHC taxonomic framework). It would have been nice if the authors would have reported the correlation matrix so independent researchers could have tested alternative models.

On a positive note.....the proposed hierarchical structure does provide a potentially useful heuristic for conceptualizing a task-analysis approach for developing mathematical reasoning interventions. The authors should be commended for their initial attempt to empirically evaluate their proposed RQ structural model...they just should have gone further in the analysis via the evaluation of competing models.
  • Christou, C., & Papageorgiou, E. (2007). A framework of mathematics inductive reasoning. Learning and Instruction, 17(1), 5566. (click here to view)

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IQ's Corner Headlines 5-17-07

All the news thats fit for IQ's Corner readers:

This is the 26th installment of IQs Corner Headlines from the Brain and Mind Blogsphere

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Wednesday, May 09, 2007

Random tidbits from the mind blogosphere - 5-9-07

  • LA has an article on death row cases, the courts, and IQ scores
  • Check out Data Mining for a nifty visualization of the blogosphere
  • Check out Mind Hacks for a post about wisdom
  • Intelligence Machines has made a post re: the prediction that artificial intelligence (AI) may surpass human intelligence after the year 2020.

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Tuesday, May 08, 2007

Random tidbits from the mind blogosphere - 5-8-07

  • An article at WebMD regarding study that suggests that brain scan test may help predict which people may suffer memory loss when they develop Alzheimer's
  • See AirForceTimes for note regarding NPR show to focus on traumatic brain injuries...featuring ABC newsman Bob Woodruff.
  • Another voice (based on a report prepared by the German research ministry) that attempts to set the record straight on the Mozart IQ effect.....I've blogged about this here for related information.
  • Multitasking may be hardest in the morning?

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Friday, May 04, 2007

Random tidbits from the mind blogosphere 5-4-07

  • New report that the drug depakote may be associated with cognitive deficits in children whose mothers took the drug while pregnant.
  • New research report that young children with autism may have difficulty recognizing early words.
  • How brains develop post at the ENL blog
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Thursday, May 03, 2007

Autism and abnormal face processing

Interesting report at Science Dailey regarding new Yale study that reports on a possible relationship between autism and abnormal face processing

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The more you drink..the more your brain will shrink ?

Psychology in the News presents summary of a longitudinal brain scan study (n=1,839) [results presented yesterday at the American Academy of Neurology annual meeting] that suggests the more you drink the more your brain may shrink...."more drink, more shrink."


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Recent literature of interest 5-2-07

This weeks (actually the last two weeks) recent literature of interest can be found by clicking here.

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Wednesday, May 02, 2007

IQ and wealth: The dumb rich and the smart poor

The following is a guest blog post by Joel Schneider (Clinical psychologist, Illinois State University), a member of IQs Corner Virtual Community of Scholars project.

The Dumb Rich and the Smart Poor


I Am as Tall as the Rocky Mountains!

(After controlling for barometric pressure)

  • Zagorsky, J. L. (in press). Do you have to be smart to be rich? The impact of IQ on wealth, income and financial distress. To appear in Intelligence. (click here to view)


How important is intelligence to financial success? Using the NLSY79, which tracks a large group of young U.S. baby boomers, this research shows that each point increase in IQ test scores raises income by between $234 and $616 per year after holding a variety of factors constant. Regression results suggest no statistically distinguishable relationship between IQ scores and wealth. Financial distress, such as problems paying bills, going bankrupt or reaching credit card limits, is related to IQ scores not linearly but instead in a quadratic relationship. This means higher IQ scores sometimes increase the probability of being in financial difficulty.


If you’ve ever been around very wealthy people, you might have noticed that they generally feel that it is in poor taste to be too concerned about money. Poor people, on the other hand, don’t have the luxury of not focusing on the importance of money. In much the same way as wealthy people think about money, smart people such as bloggers, journalists, and their typical readers generally find it distasteful to believe in the importance of intelligence and often delight in research that shows that IQ tests are irrelevant.

Now we have a study that can make both smart and rich people feel good. News reports of this article by Jay Zagorsky claim that IQ doesn’t matter when it comes to amassing wealth. Smart rich people can react to the article by thinking, “Yes, of course. It is not that I have special gifts for which I cannot take credit. No, I am rich because I earned it. Anyone can do the same. Poor people could be rich if they would only do what I did. It must be that I am a morally superior person.” People without a lot of money might be tempted to conclude, “This explains why there are so many rich idiots.” Viewed the right way, there is something in this study for everyone.

Unfortunately, the news reports about this study have oversimplified the study to the point of gross misinterpretation. The journalists cannot be blamed for the oversimplification, however. Indeed, the abstract of the article has the (entirely correct but confusing) words, “Regression results suggest no statistically distinguishable relationship between IQ scores and wealth.”

But what does this mean? It certainly sounds like IQ and wealth have no causal connection. However, as the title of this post suggests, regression results can be horribly misleading when we address issues of causality. People who remember the adage “correlation does not imply causation” might not happen to know that regression analysis is like correlation on steroids. At its core, regression is essentially the same thing as correlation and therefore it has the same weaknesses as correlation when it comes to helping us know what causes what.

Just because I can use regression to show that the houses in my neighborhood are just as tall as the Rocky Mountains after statistically controlling for barometric pressure at the summits of each house and mountain does not mean that I have proved that there is no true difference in the heights of houses and mountains. It also doesn’t prove that houses and mountains would be the same height if we were to equalize the barometric pressure differences. We know that such an analysis is stupid because we know that changing altitude causes air pressure to change and that changing air pressure has no effect on altitude.

So what exactly does the study say? First, it distinguishes between income and wealth (net worth). It is possible to amass a fortune by being frugal with a small income and it is possible to spend oneself into bankruptcy even with a high income. The article confirms that the relationship between IQ and income is, although rather modest (r = .297), statistically robust. Squaring the correlation suggests that IQ explains “only” 9% of the variance in income. This leaves 91% of the variance in personal income to be explained by other factors. The correlation of IQ and wealth is only half as large (r = .156) and accounts for a mere 2.4% of the variance in wealth. This means that a person’s net worth is determined largely by things other than IQ.

So now we can stick out our tongues, put our thumbs in our ears, wiggle our fingers, and sing, “NAH, nah, nuh, NAH, nuh!” to all our smarty-pants rivals in high school who thought they were SO smart. IQ is so insignificant. It explains only 2.4% of the variance in wealth!

…But wait, what does this look like graphically? Taking the data from Table 2 of the Jagorsky article and plotting the relationships of IQ with net worth on the left axis and income on right axis, you get a graph like the one at the top of this blog post (see above)

Yes, the low correlation between IQ and wealth does, in fact, mean that low IQ does not doom a person to poverty and that high IQ does not guarantee wealth. However, the difference between the median net worth of the lowest IQ category ($5,775) and that of the highest ($133,250) is hardly trivial. To make an analogy, your basketball skills wouldn’t be that much better if you grew an extra inch. However, to claim that height is irrelevant in basketball is utter nonsense.

The Jagorsky article is not claiming that there is no relationship between wealth and IQ. It does, however, claim that this relationship disappears after controlling for a number of sensibly selected variables such as age, marital status, education, race, inherited wealth, and so forth. If these variables were uncorrelated with IQ, the interpretation of this finding would be straightforward. Unfortunately, many of these variables are robustly correlated with IQ and this makes the interpretation of the findings rather difficult.

Now, not even the most na├»ve and enthusiastic “IQ Believer” would argue that IQ has an unmediated relationship with wealth. That is, no one believes that wealth is a direct consequence of IQ (“The test results are in and you scored quite high. Here is your check!”). IQ, if it has a causal connection with wealth at all, must act through one or more other variables. For example, high IQ may give some people a distinct advantage in acquiring more education. Many high paying jobs (e.g., jobs in the fields of law and medicine) use educational degrees as credentialing mechanisms. Thus, in this case, the proximal cause of higher income is the acquisition of educational credentials but IQ would still be an important distal cause.

Thus, when Jagorsky writes that the relationship between IQ and wealth disappears after controlling for a particular set of variables, it is essentially a claim to have identified which variables are likely to mediate the effect of IQ on wealth. What is unresolved is whether IQ really is a cause of variables such as educational attainment or simply a meaningless byproduct of education. Unfortunately, regression analyses alone cannot distinguish between the 2 causal models visually represented by a path diagram figure (click here). For that, we need other sources of information.

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Working memory, exec. attention and fluid intelligence (Gf) - again

More research suggesting that major components of fluid intelligence (Gf) may be working memory and executive/controlled attention. Check out the Developing Intelligence blog.

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IQ's Corner Headlines - 5-2-07

All the news thats fit for IQ's Corner readers:

This is the 25th installment of IQs Corner Headlines from the Brain and Mind Blogsphere

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Still bloggin' lite - on the road again, and again

Regular readers will have noted the continued dip in my posting the past few weeks. I was in DC for a trip a few weeks ago, spent last week preparing for a week long work session in Chicago, and have been in Chicago working since this Monday...and will be here till Friday.

I simply can't find much time to blog. I promise to slowly get back up to speed next week. Enjoy your time away from reading my postings....although I might do some quick FYI posts during some parts of my working meetings where I'm not actively involved in the discussions.

I shall return.

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