individual differences

Confidence is key to women's spatial skills

March, 2012

A series of experiments has found that confidence fully accounted for women’s poorer performance on a mental rotation task.

One of the few established cognitive differences between men and women lies in spatial ability. But in recent years, this ‘fact’ has been shaken by evidence that training can close the gap between the genders. In this new study, 545 students were given a standard 3D mental rotation task, while at the same time manipulating their confidence levels.

In the first experiment, 70 students were asked to rate their confidence in each answer. They could also choose not to answer. Confidence level was significantly correlated with performance both between and within genders.

On the face of it, these findings could be explained, of course, by the ability of people to be reliable predictors of their own performance. However, the researchers claim that regression analysis shows clearly that when the effect of confidence was taken into account, gender differences were eliminated. Moreover, gender significantly predicted confidence.

But of course this is still just indicative.

In the next experiment, however, the researchers tried to reduce the effect of confidence. One group of 87 students followed the same procedure as in the first experiment (“omission” group), except they were not asked to give confidence ratings. Another group of 87 students was not permitted to miss out any questions (“commission” group). The idea here was that confidence underlay the choice of whether or not to answer a question, so while the first group should perform similarly to those in the first experiment, the second group should be less affected by their confidence level.

This is indeed what was found: men significantly outperformed women in the first condition, but didn’t in the second condition. In other words, it appears that the mere possibility of not answering makes confidence an important factor.

In the third experiment, 148 students replicated the commission condition of the second experiment with the additional benefit of being allowed unlimited time. Half of the students were required to give confidence ratings.

The advantage of unlimited time improved performance overall. More importantly, the results confirmed those produced earlier: confidence ratings produced significant gender differences; there were no gender differences in the absence of such ratings.

In the final experiment, 153 students were required to complete an intentionally difficult line judgment task, which men and women both carried out at near chance levels. They were then randomly informed that their performance had been either above average (‘high confidence’) or below average (‘low confidence’). Having manipulated their confidence, the students were then given the standard mental rotation task (omission version).

As expected (remember this is the omission procedure, where subjects could miss out answers), significant gender differences were found. But there was also a significant difference between the high and low confidence groups. That is, telling people they had performed well (or badly) on the first task affected how well they did on the second. Importantly, women in the high confidence group performed as well as men in the low confidence group.

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How early environment impacts cognitive development

February, 2012

Follow-up on an early child-care program for low-income children finds long-term benefits for education and employment. A large study pinpoints the advantages children from higher-income families have over those from low-middle families. Norway shows how extending compulsory education is linked to higher IQ.

Benefits of high quality child care persist 30 years later

Back in the 1970s, some 111 infants from low-income families, of whom 98% were African-American, took part in an early childhood education program called the Abecedarian Project. From infancy until they entered kindergarten, the children attended a full-time child care facility that operated year-round. The program provided educational activities designed to support their language, cognitive, social and emotional development.

The latest data from that project, following up the participants at age 30, has found that these people had significantly more years of education than peers who were part of a control group (13.5 years vs 12.3), and were four times more likely to have earned college degrees (23% vs 6%).

They were also significantly more likely to have been consistently employed (75% had worked full time for at least 16 of the previous 24 months, compared to 53% of the control group) and less likely to have used public assistance (only 4% received benefits for at least 10% of the previous seven years, compared to 20% of the control group). However, income-to-needs ratios (income taken into account household size) didn’t vary significantly between the groups (mainly because of the wide variability; on the face of it, the means are very different, but the standard deviation is huge), and neither did criminal involvement (27% vs 28%).

See their website for more about this project.

Evidence that more time at school raises IQ

It would be interesting to see what the IQs of those groups are, particularly given that maternal IQ was around 85 for both treatment and control groups. A recent report analyzed the results of a natural experiment that occurred in Norway when compulsory schooling was increased from seven to nine years in the 1960s, meaning that students couldn’t leave until 16 rather than 14. Because all men eligible for the draft were given an IQ test at age 19, statisticians were able to look back and see what effect the increased schooling had on IQ.

They found that it had a substantial effect, with each additional year raising the average IQ by 3.7 points.

While we can’t be sure how far these results extend to other circumstances, they are clear evidence that it is possible to improve IQ through education.

Why children of higher-income parents start school with an advantage

Of course the driving idea behind improved child-care in the early years is all about the importance of getting off to a good start, and you’d expect that providing such care to children would have a greater long-term effect on IQ than simply extending time at school. Most such interventions have looked at the most deprived strata of society. An overlooked area is that of low to middle income families, who are far from having the risk factors of less fortunate families.

A British study involving 15,000 five-year-olds has found that, at the start of school, children from low to middle income families are five months behind children from higher income families in terms of vocabulary skills and have more behavior problems (they were also 8 months ahead of their lowest income peers in vocabulary).

Low-middle income (LMI) households are defined by the Resolution Foundation (who funded this research) as members of the working-age population in income deciles 2-5 who receive less than one-fifth of their gross household income from means-tested benefits (see their website for more detail on this).

Now the difference in home environment between LMI and higher income households is often not that great — particularly when you consider that it is often a difference rooted in timing. LMI households are more common in this group of families with children under five, because the parents are usually at an early stage of life. So what brings about this measurable difference in language and behavior development?

This is a tricky thing to derive from the data, and the findings must be taken with a grain of salt. And as always, interpretation is even trickier. But with this caveat, let’s see what we have. Let’s look at demographics first.

The first thing is the importance of parental education. Income plus education accounted for some 70-80% of the differences in development, with education more important for language development and income more important for behavior development. Maternal age then accounted for a further 10%. Parents in the higher-income group tended to be older and have better education (e.g., 18% of LMI mothers were under 25 at the child’s birth, compared to 6% of higher-income mothers; 30% of LMI parents had a degree compared to 67% of higher-income parents).

Interestingly, family size was equally important for language development (10%), but much less important for behavior development (in fact this was a little better in larger families). Differences in ethnicity, language, or immigration status accounted for only a small fraction of the vocabulary gap, and none of the behavior gap.

Now for the more interesting but much trickier analysis of environmental variables. The most important factor was home learning environment, accounting for around 20% of the difference. Here the researchers point to higher-income parents providing more stimulation. For example, higher-income parents were more likely to read to their 3-year-olds every day (75% vs 62%; 48% for the lowest-income group), to take them to the library at least once a month (42% vs 35% vs 26%), to take their 5-year-old to a play or concert (86% vs 75% vs 60%), to a museum/gallery (67% vs 48% vs 36%), to a sporting activity at least once a week (76% vs 57% vs 35%). Higher-income parents were also much less likely to allow their 3-year-olds to watch more than 3 hours of TV a day (7% vs 17% vs 25%). (I know the thrust of this research is the comparison between LMI and higher income, but I’ve thrown in the lowest-income figures to help provide context.)

Interestingly, the most important factor for vocabulary learning was being taken to a museum/gallery at age 5 (but remember, these correlations could go either way: it might well be that parents are more likely to take an articulate 5-year-old to such a place), with the second most important factor being reading to 3-year-old every day. These two factors accounted for most of the effects of home environment. For behavior, the most important factor was regular sport, followed by being to a play/concert, and being taken to a museum/gallery. Watching more than 3 hours of TV at age 3 did have a significant effect on both vocabulary and behavior development (a negative effect on vocabulary and a positive effect on behavior), while the same amount of TV at age 5 did not.

Differences in parenting style explained 10% of the vocabulary gap and 14% of the behavior gap, although such differences were generally small. The biggest contributors to the vocabulary gap were mother-child interaction score at age 3 and regular bedtimes at age 3. The biggest contributors to the behavior gap were regular bedtimes at age 5, regular mealtimes at age 3, child smacked at least once a month at age 5 (this factor also had a small but significant negative effect on vocabulary), and child put in timeout at least once a month at age 5.

Maternal well-being accounted for over a quarter of the behavior gap, but only a small proportion of the vocabulary gap (2% — almost all of this relates to social support score at 9 months). Half of the maternal well-being component of the behavior gap was down to psychological distress at age 5 (very much larger than the effect of psychological distress at age 3). Similarly, child and maternal health were important for behavior (18% in total), but not for vocabulary.

Material possessions, on the other hand, accounted for some 9% of the vocabulary gap, but none of the behavior gap. The most important factors here were no internet at home at age 5 (22% of LMIs vs 8% of higher-incomes), and no access to a car at age 3 (5% of LMIs had no car vs 1% of higher incomes).

As I’ve intimated, it’s hard to believe we can disentangle individual variables in the environment in an observational study, but the researchers believe the number of variables in the mix (158) and the different time points (many variables are assessed at two or more points) provided a good base for analysis.

Reference: 

[2676] Campbell, F. A., Pungello E. P., Burchinal M., Kainz K., Pan Y., Wasik B. H., et al.
(2012).  Adult outcomes as a function of an early childhood educational program: An Abecedarian Project follow-up.
Developmental Psychology;Developmental Psychology. No Pagination Specified - No Pagination Specified.

[2675] Brinch, C. N., & Galloway T A.
(2012).  Schooling in adolescence raises IQ scores.
Proceedings of the National Academy of Sciences. 109(2), 425 - 430.

Washbrook, E., & Waldfogel, J. (2011). On your marks : Measuring the school readiness of children in low-to-middle income families. Resolution Foundation, December 2011.

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How family circumstance impacts learning and memory in children

February, 2012

A large study shows the impact of having multiple family disadvantages on cognitive development. A brain scan study finds childhood maltreatment significantly reduces the size of the hippocampus, while another finds parental care can increase it.

Quarter of British children performing poorly due to family disadvantage

A British study involving over 18,000 very young children (aged 9 months to 5 years) has found that those exposed to two or more “disadvantages” (28% of the children) were significantly more likely to have impaired intellectual development, expressed in a significantly reduced vocabulary and behavioral problems.

These differences were significant at three, and for the most part tended to widen between ages three or five (cognitive development, hyperactivity, peer problems and prosocial behaviors; the gap didn’t change for emotional problems, and narrowed for conduct problems). However, only the narrowing of the conduct problem gap and the widening of the peer problem gap was statistically significant.

Ten disadvantages were identified: living in overcrowded housing; having a teenage mother; having one or more parents with depression, parent with a physical disability; parent with low basic skills; maternal smoking during pregnancy; excessive alcohol intake; financial stress, unemployment; domestic violence..

Around 41% of the children did not face any of these disadvantages, and 30% faced only one of these disadvantages. Of those facing two or more, half of those (14%) only had two, while 7% of the total group experienced three risk factors, and fewer than 2% had five or more.

There was no dominant combination of risks, but parental depression was the most common factor (19%), followed by parental disability (15%). Violence was present in only 4% of families, and both parents unemployed in only 5.5%. While there was some correlation between various risk factors, these correlations were relatively modest for the most part. The highest correlations were between unemployment and disability; violence and depression; unemployment and overcrowding.

There were ethnic differences in rate: at 48%, Bangladeshi children were most likely to be exposed to multiple disadvantages, followed by Pakistani families (34%), other (including mixed) (33%), black African (31%), black Caribbean (29%), white (28%) and Indian (20%).

There were also differences depending on family income. Among those in the lowest income band (below £10,400 pa) — into which 21% of the families fell, the same proportion as is found nationally — nearly half had at least two risk factors, compared to 27% of those in families above this threshold. Moreover, children in families with multiple risk factors plus low income showed the lowest cognitive development (as measured by vocabulary).

Childhood maltreatment reduces size of hippocampus

In this context, it is interesting to note a recent finding that three key areas of the hippocampus were significantly smaller in adults who had experienced maltreatment in childhood. In this study, brain scans were taken of nearly 200 young adults (18-25), of whom 46% reported no childhood adversity and 16% reported three or more forms of maltreatment. Maltreatment was most commonly physical and verbal abuse from parents, but also included corporal punishment, sexual abuse and witnessing domestic violence.

Reduced volume in specific hippocampus regions (dentate gyrus, cornu ammonis, presubiculum and subiculum) was still evident after such confounding factors as a history of depression or PTSD were taken into account. The findings support the theory that early stress affects the development of subregions in the hippocampus.

While mother’s nurturing grows the hippocampus

Supporting this, another study, involving 92 children aged 7 to 10 who had participated in an earlier study of preschool depression, has found that those children who received a lot of nurturing from their parent (generally mother) developed a larger hippocampus than those who didn’t.

‘Nurturing’ was assessed in a videotaped interaction at the time of the preschool study. In this interaction, the parent performed a task while the child waited for her to finish so they could open an attractive gift. How the parent dealt with this common scenario — the degree to which they helped the child through the stress — was evaluated by independent raters.

Brain scans revealed that children who had been nurtured had a significantly larger hippocampus than those whose mothers were not as nurturing, and (this was the surprising bit), this effect was greater among the healthy, non-depressed children. Among this group, those with a nurturing parent had hippocampi which were on average almost 10% larger than those whose parent had not been as nurturing.

Reference: 

First study:
Sabates, R., Dex, S., Sabates, R., & Dex, S. (2012). Multiple risk factors in young children’s development. CLS Cohort Studies Working paper 2012/1.
Full text available at http://www.cls.ioe.ac.uk/news.aspx?itemid=1661&itemTitle=More+than+one+i...

Second study:
[2741] Teicher, M. H., Anderson C. M., & Polcari A.
(2012).  Childhood maltreatment is associated with reduced volume in the hippocampal subfields CA3, dentate gyrus, and subiculum.
Proceedings of the National Academy of Sciences.
Full text available at http://www.pnas.org/content/early/2012/02/07/1115396109.abstract?sid=f73...

Third study:
[2734] Luby, J. L., Barch D. M., Belden A., Gaffrey M. S., Tillman R., Babb C., et al.
(2012).  Maternal support in early childhood predicts larger hippocampal volumes at school age.
Proceedings of the National Academy of Sciences.

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Cognitive training for older adults can also change a personality trait

February, 2012

A program designed to improve reasoning ability in older adults also increased their openness to new experiences.

Openness to experience – being flexible and creative, embracing new ideas and taking on challenging intellectual or cultural pursuits – is one of the ‘Big 5’ personality traits. Unlike the other four, it shows some correlation with cognitive abilities. And, like them, openness to experience does tend to decline with age.

However, while there have been many attempts to improve cognitive function in older adults, to date no one has tried to increase openness to experience. Naturally enough, one might think — it’s a personality trait, and we are not inclined to view personality traits as amenable to ‘training’. However, recently there have been some indications that personality traits can be changed, through cognitive interventions or drug treatments. In this new study, a cognitive training program for older adults also produced increases in their openness to experience.

The study involved 183 older adults (aged 60-94; average age 73), who were randomly assigned to a 16-week training program or a waiting-list control group. The program included training in inductive reasoning, and puzzles that relied in part on inductive reasoning. Most of this activity was carried out at home, but there were two 1-hour classroom sessions: one to introduce the inductive reasoning training, and one to discuss strategies for Sudoku and crosswords.

Participants came to the lab each week to hand in materials and pick up the next set. Initially, they were given crossword and Sudoku puzzles with a wide range of difficulty. Subsequently, puzzle sets were matched to each participant’s skill level (assessed from the previous week’s performance). Over the training period, the puzzles became progressively more difficult, with the steps tailored to each individual.

The inductive reasoning training involved learning to recognize novel patterns and use them to solve problems. In ‘basic series problems’, the problems required inference from a serial pattern of words, letters, or numbers. ‘Everyday serial problems’ included problems such as completing a mail order form and answering questions about a bus schedule. Again, the difficulty of the problems increased steadily over the training period.

Participants were asked to spend at least 10 hours a week on program activities, and according to the daily logs they filled in, they spent an average of 11.4 hours a week. In addition to the hopefully inherent enjoyment of the activities, those who recorded 10 hours were recognized on a bulletin board tally sheet and entered into a raffle for a prize.

Cognitive and personality testing took place 4-5 weeks prior to the program starting, and 4-5 weeks after program end. Two smaller assessments also took place during the program, at week 6 and week 12.

At the end of the program, those who had participated had significantly improved their pattern-recognition and problem-solving skills. This improvement went along with a moderate but significant increase in openness. Analysis suggested that this increase in openness occurred independently of improvement in inductive reasoning.

The benefits were specific to inductive reasoning and openness, with no significant effects on divergent thinking, processing speed, verbal ability, or the other Big 5 traits.

The researchers suggest that the carefully stepped training program was important in leading to increased openness, allowing the building of a growing confidence in their reasoning abilities. Openness to experience contributes to engagement and enjoyment in stimulating activity, and has also been linked to better health and decreased mortality risk. It seems likely, then, that increases in openness can be part of a positive feedback cycle, leading to greater and more sustained engagement in mentally stimulating activities.

The corollary is that decreases in openness may lead to declines in cognitive engagement, and then to poorer cognitive function. Indeed it has been previously suggested that openness to experience plays a role in cognitive aging.

Clearly, more research is needed to tease out how far these findings extend to other activities, and the importance of scaffolding (carefully designing cognitive activities on an individualized basis to support learning), but this work reveals an overlooked aspect to the issue of mental stimulation for preventing age-related cognitive decline.

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Genes

Older news items (pre-2010) brought over from the old website

‘Memory gene’ impacts driving performance

People with a particular variant (“met”) of the COMT gene performed more than 20% worse on a driving test than people without it. About 30% of Americans have the variant, which limits the availability of the vital protein BDNF during activity. Previous studies have shown that in people with the variant, episodic (event) memory is poorer, and a smaller portion of the brain is stimulated when doing a task. The study involved 29 people, of whom 7 had the gene variant, driving 15 laps on a simulator that required them to learn the nuances of a track programmed to have difficult curves and turns. The test was repeated 4 days later. Those with the variant did worse on both tests than the other participants, and they remembered less the second time. However, the gene isn’t all bad — although carriers don't recover as well after a stroke, they retain their mental sharpness longer in the case of neurodegenerative disease.

[1283] McHughen, S. A., Rodriguez P. F., Kleim J. A., Kleim E. D., Crespo L M., Procaccio V., et al.
(2010).  BDNF Val66Met Polymorphism Influences Motor System Function in the Human Brain.
Cereb. Cortex. 20(5), 1254 - 1262.

http://www.sciencedaily.com/releases/2009/10/091028134637.htm
http://www.miller-mccune.com/news/are-you-a-bad-driver-it-may-not-be-your-fault-1577
http://www.eurekalert.org/pub_releases/2009-10/uoc--bdm102809.php

Two studies help explain the spacing effect

I talked about the spacing effect in my last newsletter. Now it seems we can point to the neurology that produces it. Not only that, but the study has found a way of modifying it, to improve learning. It’s a protein called SHP-2 phosphatase that controls the spacing effect by determining how long resting intervals between learning sessions need to last so that long-lasting memories can form. The discovery happened because more than 50% of those with a learning disorder called Noonan's disease have mutations in a gene called PTP11, which encodes the SHP-2 phosphatase protein. These mutations boost the activity levels of SHP-2 phosphatase, which, in genetically modified fruit flies, disturbs the spacing effect by increasing the interval before a new chemical signal can occur (it is the repeated formation and decay of these signals that produces memory). Accordingly, those with the mutation need longer periods between repetitions to establish long-term memory.

[1433] Pagani, M. R., Oishi K., Gelb B. D., & Zhong Y.
(2009).  The Phosphatase SHP2 Regulates the Spacing Effect for Long-Term Memory Induction.
Cell. 139(1), 186 - 198.

http://www.eurekalert.org/pub_releases/2009-10/cshl-csi092809.php

A study involving Aplysia (often used as a model for learning because of its simplicity and the large size of its neural connections) reveals that spaced and massed training lead to different types of memory formation. The changes at the synapses that underlie learning are controlled by the release of the neurotransmitter serotonin. Four to five spaced applications of serotonin generated long-term changes in the strength of the synapse and less activation of the enzyme Protein kinase C Apl II, leading to stronger connections between neurons. However, when the application of serotonin was continuous (as in massed learning), there was much more activation of PKC Apl II, suggesting that activation of this enzyme may block the mechanisms for generating long-term memory, while retaining mechanisms for short-term memory.

[1504] Villareal, G., Li Q., Cai D., Fink A. E., Lim T., Bougie J. K., et al.
(2009).  Role of Protein Kinase C in the Induction and Maintenance of Serotonin-Dependent Enhancement of the Glutamate Response in Isolated Siphon Motor Neurons of Aplysia californica.
J. Neurosci.. 29(16), 5100 - 5107.

http://www.eurekalert.org/pub_releases/2009-10/mu-wow100109.php

Smart gene helps brain cells communicate

For the second time, scientists have created a smarter rat by making their brains over-express CaMKII, a protein that acts as a promoter and signaling molecule for the NR2B subunit of the NMDA receptor. Over-expressing the gene lets brain cells communicate a fraction of a second longer. The research indicates that it plays a crucial role in initiating long-term potentiation. The NR2B subunit is more common in juvenile brains; after puberty the NR2A becomes more common. This is one reason why young people tend to learn and remember better — because the NR2B keeps communication between brain cells open maybe just a hundred milliseconds longer than the NR2A. Although this genetic modification is not something that could probably be replicated in humans, it does validate NR2B as a drug target for improving memory in healthy individuals as well as those struggling with Alzheimer's or mild dementia.

[599] Wang, D., Cui Z., Zeng Q., Kuang H., Wang P. L., Tsien J. Z., et al.
(2009).  Genetic Enhancement of Memory and Long-Term Potentiation but Not CA1 Long-Term Depression in NR2B Transgenic Rats.
PLoS ONE. 4(10), e7486 - e7486.

Full text at http://dx.plos.org/10.1371/journal.pone.0007486

http://www.eurekalert.org/pub_releases/2009-10/mcog-sr101909.php

Common variation in gene linked to structural changes in the brain

Variations in the regions of the gene MECP2, previously associated with Retts Syndrome, autism, and mental retardation, has been found to be associated with changes in brain structure in both healthy individuals and patients with neurological and psychiatric disorders. The study used data from 289 healthy and psychotic subjects (the TOP study), and 655 healthy and demented patients (mostly Alzheimer's; from the ADNI study). The most significant genetic variation resulted in reduced surface area in the cortex (in particular in the cuneus, fusiform gyrus, pars triangularis), and was specific to males.

[297] Schork, N. J., Andreassen O. A., Dale A. M., Joyner A. H., Roddey J. Cooper, Bloss C. S., et al.
(2009).  A common MECP2 haplotype associates with reduced cortical surface area in humans in two independent populations.
Proceedings of the National Academy of Sciences. 106(36), 15483 - 15488.

http://www.eurekalert.org/pub_releases/2009-08/uoc--cvi081709.php
http://www.eurekalert.org/pub_releases/2009-08/sri-sru081809.php

Genes more important for IQ as children get older

Data from six studies carried out in the US, the UK, Australia and the Netherlands, involving a total of 11,000 pairs of twins, has revealed that genes become more important for intelligence as we get older. The researchers calculated that genes accounted for some 41% of the variation in intelligence in 9 year olds, rising to 55% in 12 year olds, and 66% in 17 year olds. It was suggested that as they get older, children get better at controlling (or perhaps are allowed to have more control over) their environment, which they do in a way that accentuates their ‘natural’ abilities — bright children feed their abilities; less bright children choose activities and friends that are less challenging.

Haworth, C.M.A. et al. 2009. R Plomin The heritability of general cognitive ability increases linearly from childhood to young adulthood. Molecular Psychiatry, advance online publication 2 June 2009; doi: 10.1038/mp.2009.55

http://www.newscientist.com/article/mg20327174.600-genes-drive-iq-more-as-kids-get-older.html

Early maternal experience can affect memory in her offspring

A study of pre-adolescent mice with a genetically-created defect in memory has found that a mere two weeks exposure to a stimulating environment resulted in a reversal of the memory defect. But most surprisingly, it was also found that this effect was passed on to the next generation, even though they had the same genetic defect and even though they had no such experience themselves, and even when they were reared by other mice (not their mothers). It’s worth emphasizing that the enrichment occurs for the mother long before she’s fertile, yet still benefits her offspring. The finding adds to many recent studies showing that genes are more malleable than we thought.

[1434] Arai, J. A., Li S., Hartley D. M., & Feig L. A.
(2009).  Transgenerational Rescue of a Genetic Defect in Long-Term Potentiation and Memory Formation by Juvenile Enrichment.
J. Neurosci.. 29(5), 1496 - 1502.

http://www.physorg.com/news152905156.html
http://www.eurekalert.org/pub_releases/2009-02/rumc-wym020209.php
http://www.eurekalert.org/pub_releases/2009-02/tuhs-dyk012909.php

A gene that influences intelligence

A study involving more than 2000 people from 200 families has found a link between the gene CHRM2, that activates multiple signaling pathways in the brain involved in learning, memory and other higher brain functions, and performance IQ. Researchers found that several variations within the CHRM2 gene (which is on chromosome 7) could be correlated with slight differences in performance IQ scores, which measure a person's visual-motor coordination, logical and sequential reasoning, spatial perception and abstract problem solving skills, and when people had more than one positive variation in the gene, the improvements in performance IQ were cumulative. Intelligence is a complex attribute that results from a combination of many genetic and environmental factors, so don’t interpret this finding to mean we’ve found a gene for intelligence.

[1173] Edenberg, H., Porjesz B., Begleiter H., Hesselbrock V., Goate A., Bierut L., et al.
(2007).  Association of CHRM2 with IQ: Converging Evidence for a Gene Influencing Intelligence.
Behavior Genetics. 37(2), 265 - 272.

http://www.eurekalert.org/pub_releases/2007-02/wuso-gag022607.php

Common gene version optimizes thinking but carries a risk

On the same subject, another study has found that the most common version of DARPP-32, a gene that shapes and controls a circuit between the striatum and prefrontal cortex, optimizes information filtering by the prefrontal cortex, thus improving working memory capacity and executive control (and thus, intelligence). However, the same version was also more prevalent among people who developed schizophrenia, suggesting that a beneficial gene variant may translate into a disadvantage if the prefrontal cortex is impaired. In other words, one of the things that make humans more intelligent as a species may also make us more vulnerable to schizophrenia.

[864] Kolachana, B., Kleinman J. E., Weinberger D. R., Meyer-Lindenberg A., Straub R. E., Lipska B. K., et al.
(2007).  Genetic evidence implicating DARPP-32 in human frontostriatal structure, function, and cognition.
Journal of Clinical Investigation. 117(3), 672 - 682.

http://www.sciencedaily.com/releases/2007/02/070208230059.htm
http://www.eurekalert.org/pub_releases/2007-02/niom-cgv020707.php

Genetic cause for word-finding disease

Primary Progressive Aphasia is a little-known form of dementia in which people lose the ability to express themselves and understand speech. People can begin to show symptoms of PPA as early as in their 40's and 50's. A new study has found has discovered a gene mutation in two unrelated families in which nearly all the siblings suffered from PPA. The mutations were not observed in the healthy siblings or in more than 200 controls.

[1164] Hutton, M. L., Graff-Radford N. R., Mesulam M. Marsel, Johnson N., Krefft T. A., Gass J. M., et al.
(2007).  Progranulin Mutations in Primary Progressive Aphasia: The PPA1 and PPA3 Families.
Arch Neurol. 64(1), 43 - 47.

http://www.eurekalert.org/pub_releases/2007-01/nu-rdg011507.php

Longevity gene also helps retain cognitive function

The Longevity Genes Project has studied 158 people of Ashkenazi, or Eastern European Jewish, descent who were 95 years of age or older. Those who passed a common test of mental function were two to three times more likely to have a common variant of a gene associated with longevity (the CETP gene) than those who did not. When the researchers studied another 124 Ashkenazi Jews between 75 and 85 years of age, those subjects who passed the test of mental function were five times more likely to have this gene variant than their counterparts. The gene variant makes cholesterol particles in the blood larger than normal.

[916] Barzilai, N., Atzmon G., Derby C. A., Bauman J. M., & Lipton R. B.
(2006).  A genotype of exceptional longevity is associated with preservation of cognitive function.
Neurology. 67(12), 2170 - 2175.

http://tinyurl.com/yrf5s4
http://www.eurekalert.org/pub_releases/2006-12/aaon-lga121906.php

'Memory gene' identified

Analysis of the human genome has revealed a gene associated with memory performance. The gene is called Kibra, and is expressed in the hippocampus. According to brain scans, people with the version of the gene related to poorer memory potential had to tax their brains harder to remember the same amount of information.

[2658] Papassotiropoulos, A., Stephan D. A., Huentelman M. J., Hoerndli F. J., Craig D. W., Pearson J. V., et al.
(2006).  Common Kibra Alleles Are Associated with Human Memory Performance.
Science. 314(5798), 475 - 478.

http://www.eurekalert.org/pub_releases/2006-10/ttgr-rti101906.php

Protein found to inhibit conversion to long-term memory

In a study using genetically engineered mice, researchers have found that mice without a protein called GCN2 acquire new information that doesn’t fade as easily as it does in normal mice. After weak training on the Morris water maze, their spatial memory was enhanced, but it was impaired after more intense training. The researchers concluded that GCN2 may prevent new information from being stored in long-term memory, suggesting the conversion of new information into long-term memory requires both the activation of molecules that facilitate memory storage, and the silencing of proteins such as GCN2 that inhibit memory storage.

[949] Yoshida, M., Imataka H., Cuello C. A., Seidah N., Sossin W., Lacaille J-C., et al.
(2005).  Translational control of hippocampal synaptic plasticity and memory by the eIF2[alpha] kinase GCN2.
Nature. 436(7054), 1166 - 1173.

http://www.eurekalert.org/pub_releases/2005-08/uom-mrp082905.php

Closing in on the genes involved in human intelligence

A genetic study claims to have identified two regions of the human genome that appear to explain variation in IQ. Previous research has suggested that between 40% and 80% of variation in human intelligence (as measured by IQ tests) can be attributed to genetic factors, but research has so far failed to identify these genes. The new study has identified specific locations on Chromosomes 2 and 6 as being highly influential in determining IQ, using data from 634 sibling pairs. The region on Chromosome 2 that shows significant links to performance IQ overlaps a region associated with autism. The region on Chromosome 6 that showed strong links with both full-scale and verbal IQ marginally overlapped a region implicated in reading disability and dyslexia.

[382] Posthuma, D., Luciano M., Geus E., Wright M., Slagboom P., Montgomery G., et al.
(2005).  A Genomewide Scan for Intelligence Identifies Quantitative Trait Loci on 2q and 6p.
The American Journal of Human Genetics. 77(2), 318 - 326.

http://www.qimr.edu.au/news/index.html

Human cerebellum and cortex age in very different ways

Analysis of gene expression in five different regions of the brain's cortex has found that brain changes with aging were pronounced and consistent across the cortex, but changes in gene expression in the cerebellum were smaller and less coordinated. Researchers were surprised both by the homogeneity of aging within the cortex and by the dramatic differences between cortex and cerebellum. They also found that chimpanzees' brains age very differently from human brains; the findings cast doubt on the effectiveness of using rodents to model various types of neurodegenerative disease.

[951] Fraser, H. B., Khaitovich P., Plotkin J. B., Pääbo S., & Eisen M. B.
(2005).  Aging and Gene Expression in the Primate Brain.
PLoS Biol. 3(9), e274 - e274.

http://www.eurekalert.org/pub_releases/2005-08/hu-hca072805.php

More light on a common developmental disorder

Chromosome 22q11.2 deletion syndrome is the most common genetic deletion syndrome, and causes symptoms such as heart defects, cleft palate, abnormal immune responses and cognitive impairments. Two related studies have recently cast more light on these cognitive impairments. Previously it was known that numerical abilities were impaired more than verbal skills. The new study found children with the chromosome deletion performed more poorly on experiments designed to test visual attention orienting, enumerating, and judging numerical magnitudes. All three tasks relate to how the children mentally represent objects and the spatial relationships among them, supporting previous arguments that such visual-spatial skills are a fundamental foundation to the later learning of counting and mathematics. The second study found that such children had changes in the shape, size and position of the corpus callosum, the main bridge between the two hemispheres.

[1139] Simon, T. J., Bearden C. E., Mc-Ginn D MD., & Zackai E.
(2005).  Visuospatial and Numerical Cognitive Deficits in Children with Chromosome 22Q11.2 Deletion Syndrome.
Cortex. 41(2), 145 - 155.

[812] Simon, T. J., Ding L., Bish J. P., McDonald-McGinn D. M., Zackai E. H., & Gee J.
(2005).  Volumetric, connective, and morphologic changes in the brains of children with chromosome 22q11.2 deletion syndrome: an integrative study.
NeuroImage. 25(1), 169 - 180.

http://www.eurekalert.org/pub_releases/2005-03/chop-lbt030205.php

Closing in on the genes involved in context learning

A study involving the worm C. elegans (whose genome has been completely sequenced) has demonstrated that even such simple animals demonstrate memory that is sensitive to context. In the study, the worms were trained in a salt medium to associate a particular smell with starvation. When placed in a different salt medium, the worms didn’t respond to the smell, but showed distaste when experiencing the smell in the context of the salt medium in which they were trained. More importantly, use of this animal has enabled the researchers to identify a genetic mutation that affects this type of memory. The next step will be to identify the specific gene involved in processing environmental cues.

[1072] Law, E., Nuttley W. M., & van der Kooy D.
(2004).  Contextual Taste Cues Modulate Olfactory Learning in C. elegans by an Occasion-Setting Mechanism.
Current Biology. 14(14), 1303 - 1308.

http://www.eurekalert.org/pub_releases/2004-07/uot-eil072704.php

Some brains age more rapidly than others

Investigation of the patterns of gene expression in post-mortem brain tissue has revealed two groups of genes with significantly altered expression levels in the brains of older individuals. The most significantly affected were mostly those related to learning and memory. One of the most interesting, and potentially useful, findings, is that patterns of gene expression were quite similar in the brains of younger adults. Very old adults also showed similar patterns, although the similarity was less. But the greatest degree of individual variation occurred in those aged between 40 and 70. Some of these adults showed gene patterns that looked more like the young group, whereas others showed gene patterns that looked more like the old group. It appears that gene changes start around 40 in some people, but not in others. It also appears that those genes that are affected by age are unusually vulnerable to damage from agents such as free radicals and toxins in the environment, suggesting that lifestyle in young adults may play a part in deciding rate and degree of cognitive decline in later years.

[1335] Lu, T., Pan Y., Kao S-Y., Li C., Kohane I., Chan J., et al.
(2004).  Gene regulation and DNA damage in the ageing human brain.
Nature. 429(6994), 883 - 891.

http://www.eurekalert.org/pub_releases/2004-06/chb-dgi060204.php

Could memory performance and spatial learning be genetically based?

A new rat study provides evidence that individual differences in some cognitive functions (specifically spatial navigation, in this experiment) may have a genetic basis.

[1267] Ruiz-Opazo, N., & Tonkiss J.
(2004).  X-linked loci influence spatial navigation performance in Dahl rats.
Physiological Genomics. 16(3), 329 - 333.

http://www.eurekalert.org/pub_releases/2004-02/aps-cmp020404.php

Gene essential for development of normal brain connections discovered

After birth, learning and experience change the architecture of the brain dramatically. The structure of individual neurons, or nerve cells, changes during learning to accommodate new connections between neurons. Neuroscientists believe these structural changes are initiated when neurons are activated, causing calcium ions to flow into cells and alter the activity of genes. Now the first gene, CREST, known to mediate these changes in the structure of neurons in response to calcium, has been discovered. In the study, it was found that mice lacking this gene didn’t develop normally in response to sensory experience, and their brains, while normal at birth, later showed far less interconnectivity between neurons. The gene produces a protein that, in adult humans, is produced in the hippocampus. It is therefore speculated that the protein may be necessary for learning and memory storage. The discovery of this gene may have implications for certain types of learning disorders in humans.

[915] Aizawa, H., Hu S-C., Bobb K., Balakrishnan K., Ince G., Gurevich I., et al.
(2004).  Dendrite development regulated by CREST, a calcium-regulated transcriptional activator.
Science (New York, N.Y.). 303(5655), 197 - 202.

http://www.eurekalert.org/pub_releases/2004-01/uoc--gef010804.php

Brain protein affecting learning and memory discovered

A significant new brain protein has been identified. Cypin is found throughout the body, but in the brain it now appears that it regulates neuron branching in the hippocampus. Such branching is thought to increase when learning occurs, and a reduction in branching is associated with certain neurological diseases. Discovery of this protein opens the possibility of new drug therapies for treating neurological disorders, and perhaps even memory-enhancing drugs.

[696] Akum, B. F., Chen M., Gunderson S. I., Riefler G. M., Scerri-Hansen M. M., & Firestein B. L.
(2004).  Cypin regulates dendrite patterning in hippocampal neurons by promoting microtubule assembly.
Nat Neurosci. 7(2), 145 - 152.

http://www.eurekalert.org/pub_releases/2004-01/rtsu-rsd011204.php
http://news.independent.co.uk/world/science_medical/story.jsp?story=482567

Amphetamine helps or hinders cognitive function depending on your genes

Everyone inherits two copies of the catecho-O-methyltransferase (COMT) gene, that codes for the enzyme that metabolizes neurotransmitters like dopamine and norepinephrine. It comes in two common versions. One version, met, contains the amino acid methionine at a point in its chemical sequence where the other version, val, contains a valine. Depending on the mix of variants inherited, a person's COMT genes can be typed met/met, val/val, or val/met. People with the val/val variant appear to have reduced prefrontal dopamine activity and less efficient prefrontal information processing, along with slightly increased risk for schizophrenia. People with val/met have more efficient prefrontal function, and people with met/met the most efficient.
In a recent imaging study, 27 volunteers (10 val/val, 11 val/met, and 6 met/met) performed a variety of cognitive tasks that involved working memory and executive functioning, after taking either amphetamine or a placebo. Since amphetamine boosts dopamine activity in the prefrontal cortex, the researchers predicted that the drug would enable val/val types to boost their low level of dopamine and perform better on cognitive tasks that depend on the prefrontal cortex. On the other hand, those with met/met should be hindered by amphetamine. The study confirmed these predictions - val/val subjects on amphetamine performed comparably to met/met types in normal conditions, while met/met subjects on amphetamine performed worse than subjects with val/val types in normal conditions.
Amphetamines and other drugs that affect prefrontal dopamine systems are used to treat Attention Deficit Hyperactivity Disorder (ADHD), and other psychiatric illnesses, and some people respond better than others to these medications. About 15-20% of individuals in populations of European ancestry have the met/met COMT gene type.

[1292] Mattay, V. S., Goldberg T. E., Fera F., Hariri A. R., Tessitore A., Egan M. F., et al.
(2003).  Catechol O-methyltransferase val158-met genotype and individual variation in the brain response to amphetamine.
Proceedings of the National Academy of Sciences of the United States of America. 100(10), 6186 - 6191.

http://www.eurekalert.org/pub_releases/2003-05/niom-gep050703.php

Gene linked to poor episodic memory

Brain derived neurotrophic factor (BDNF) plays a key role in neuron growth and survival and, it now appears, memory. We inherit two copies of the BDNF gene - one from each parent - in either of two versions. Slightly more than a third inherit at least one copy of a version nicknamed "met," which the researchers have now linked to poorer memory. Those who inherit the “met” gene appear significantly worse at remembering events that have happened to them, probably as a result of the gene’s effect on hippocampal function. Most notably, those who had two copies of the “met” gene scored only 40% on a test of episodic (event) memory, while those who had two copies of the other version scored 70%. Other types of memory did not appear to be affected. It is speculated that having the “met” gene might also increase the risk of disorders such as Alzheimer’s and Parkinson's.

[1039] Dean, M., Egan M. F., Kojima M., Callicott J. H., Goldberg T. E., Kolachana B. S., et al.
(2003).  The BDNF val66met Polymorphism Affects Activity-Dependent Secretion of BDNF and Human Memory and Hippocampal Function.
Cell. 112(2), 257 - 269.

http://www.nih.gov/news/pr/jan2003/nimh-23.htm
http://www.eurekalert.org/pub_releases/2003-01/niom-hga012203.php
http://news.bbc.co.uk/1/hi/health/2687267.stm

tags memworks: 

Intelligence

Older news items (pre-2010) brought over from the old website

Aerobic fitness boosts IQ in teenage boys

Data from the 1.2 million Swedish men born between 1950 and 1976 who enlisted for mandatory military service at the age of 18 has revealed that on every measure of cognitive performance, average test scores increased according to aerobic fitness — but not muscle strength. The link was strongest for logical thinking and verbal comprehension, and the association was restricted to cardiovascular fitness. The results of the study also underline the importance of getting healthier between the ages of 15 and 18 while the brain is still changing — those who improved their cardiovascular health between 15 and 18 showed significantly greater intelligence scores than those who became less healthy over the same time period. Those who were fittest at 18 were also more likely to go to college. Although association doesn’t prove cause, the fact that the association was only with cardiovascular fitness and not strength supports a cardiovascular effect on brain function. Results from over 260,000 full-sibling pairs, over 3,000 sets of twins, and more than 1,400 sets of identical twins, also supports a causal relationship.

[1486] Åberg, M AI., Pedersen N. L., Torén K., Svartengren M., Bäckstrand B., Johnsson T., et al.
(2009).  Cardiovascular fitness is associated with cognition in young adulthood.
Proceedings of the National Academy of Sciences. 106(49), 20906 - 20911.

http://www.physorg.com/news179415275.html
http://www.telegraph.co.uk/science/science-news/6692474/Physical-health-leads-to-mental-health.html

Confidence as important as IQ in exam success

I’ve talked repeatedly about the effects of self-belief on memory and cognition. One important area in which this is true is that of academic achievement. Evidence indicates that your perceived abilities matter, just as much? more than? your actual abilities. It has been assumed that self perceived abilities, self-confidence if you will, is a product mainly of nurture. Now a new twin study provides evidence that nurture / environment may only provide half the story; the other half may lie in the genes. The study involved 1966 pairs of identical twins and 1877 pairs of fraternal twins. The next step is to tease out which of these genes are related to IQ and which to personality variables.

[1080] Greven, C. U., Harlaar N., Kovas Y., Chamorro-Premuzic T., & Plomin R.
(2009).  More Than Just IQ: School Achievement Is Predicted by Self-Perceived Abilities—But for Genetic Rather Than Environmental Reasons.
Psychological Science. 20(6), 753 - 762.

http://www.newscientist.com/article/dn17187-confidence-as-important-as-iq-in-exam-success.html

Children of older fathers perform less well in intelligence tests during infancy

Reanalysis of a dataset of over 33,000 children born between 1959 and 1965 and tested at 8 months, 4 years, and 7 years, has revealed that the older the father, the more likely the child was to have lower scores on the various tests used to measure the ability to think and reason, including concentration, learning, memory, speaking and reading skills. In contrast, the older the mother, the higher the scores of the child in the cognitive tests.

[1447] Saha, S., Barnett A. G., Foldi C., Burne T. H., Eyles D. W., Buka S. L., et al.
(2009).  Advanced Paternal Age Is Associated with Impaired Neurocognitive Outcomes during Infancy and Childhood.
PLoS Med. 6(3), e1000040 - e1000040.

Full text available at http://medicine.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pmed.1000040

http://www.eurekalert.org/pub_releases/2009-03/plos-coo030309.php

Brain-training to improve working memory boosts fluid intelligence

General intelligence is often separated into "fluid" and "crystalline" components, of which fluid intelligence is considered more reflective of “pure” intelligence (for more on this, see my article), and largely resistant to training and learning effects. However, in a new study in which participants were given a series of training exercises designed to improve their working memory, fluid intelligence was found to have significantly improved, with the amount of improvement increasing with time spent training. The small study contradicts decades of research showing that improving on one kind of cognitive task does not improve performance on other kinds, so has been regarded with some skepticism by other researchers. More research is definitely needed, but the memory task did differ from previous studies, engaging executive functions such as those that inhibit irrelevant items, monitor performance, manage two tasks simultaneously, and update memory.

[1183] Jaeggi, S. M., Buschkuehl M., Jonides J., & Perrig W. J.
(2008).  From the Cover: Improving fluid intelligence with training on working memory.
Proceedings of the National Academy of Sciences. 105(19), 6829 - 6833.

http://www.physorg.com/news128699895.html
http://www.sciam.com/article.cfm?id=study-shows-brain-power-can-be-bolstered

Effect of schooling on achievement gaps within racial groups

Analysis of data from a national sample (U.S.) of 8,060 students, collected at four points in time, starting in kindergarten and ending in the spring of fifth grade, has found evidence that education has an impact in closing the achievement gap for substantial numbers of children. High-performing groups in reading were found among all races. About 30% of European Americans, 26% of African Americans and 45% of Asian Americans were in high-achieving groups by the spring of fifth grade — these groups included approximately 23% of African American children and 36% of Asian children who caught up with the initial group of high achievers over time. Only around 4% of European American students were in catch-up groups, because a higher percentage of European Americans started kindergarten as high achievers in reading. The situation was different for Hispanic students, however.  By the end of fifth grade, just over 5% of Hispanic children were high achievers in reading, while the remainder tested in the middle range. There were no low achievers and no catch-up groups. A different pattern was found in math. Only 17% of European American students were high-achievers in math by the end of fifth grade, including 13% who started kindergarten at a lower achievement level and caught up over time.  About 18% of Asian Americans were high-achievers at the end of fifth grade (11% catch-up). Only 0.3% of African Americans were high achievers at the end of fifth grade, and 26% were medium-high achievers. But about 16% of Hispanics were high achievers in math. There were no catch-up groups for either the African Americans or the Hispanics. This suggests that current schooling doesn't have as strong an impact on math achievement as it does in reading.

The study was presented in Washington, D.C. at the 2008 annual meeting of the Society for Research on Educational Effectiveness.

http://www.physorg.com/news123859991.html

Autism non-verbal not unintelligent

New findings suggest that the association of autism with low intelligence is a product of their language difficulties. Testing autistic kids and normal kids on two popular IQ tests — the WISC (which relies heavily on language) and Raven's Progressive Matrices (considered the best test of "fluid intelligence", and a test that doesn't require much language) found that while not a single autistic child scored in the "high intelligence" range of the WISC, a third did on the Raven's. A third of the autistics had WISC scores in the mentally retarded range, but only one in 20 scored that low on the Raven's test. The non-autistic children scored similarly on both tests. The same results occurred when the experiment was run on autistic and normal adults.

[580] Dawson, M., Soulières I., Gernsbacher M A., & Mottron L.
(2007).  The level and nature of autistic intelligence.
Psychological Science: A Journal of the American Psychological Society / APS. 18(8), 657 - 662.

http://www.physorg.com/news105376203.html
http://www.eurekalert.org/pub_releases/2007-08/afps-tmo080307.php

Being treated as oldest linked to IQ

The question of whether there is an IQ advantage to being the first-born has long been debated. Now analysis of IQ test results of 241,310 Norwegians drafted into the armed forces between 1967 and 1976 has revealed that the average IQ of first-born men was 103.2 while second-born men averaged 101.2 and third-borns, 100.0. However, second-born men whose older sibling died in infancy scored 102.9, and if both older siblings died young, the third-born score rose to 102.6. This suggests the advantage lies in the social rank in the family and not birth order as such.

[589] Kristensen, P., & Bjerkedal T.
(2007).  Explaining the Relation Between Birth Order and Intelligence.
Science. 316(5832), 1717 - 1717.

http://www.nature.com/news/2007/070618/full/070618-14.html

Executive function as important as IQ for math success

A study of 141 preschoolers from low-income homes has found that a child whose IQ and executive functioning were both above average was three times more likely to succeed in math than a child who simply had a high IQ. The parts of executive function that appear to be particularly linked to math ability in preschoolers are working memory and inhibitory control. In this context, working memory may be thought of as the ability to keep information or rules in mind while performing mental tasks. Inhibitory control is the ability to halt automatic impulses and focus on the problem at hand. Inhibitory control was also important for reading ability. The finding offers the hope that training to improve executive function will improve academic performance.

[1256] Blair, C., & Razza R P.
(2007).  Relating Effortful Control, Executive Function, and False Belief Understanding to Emerging Math and Literacy Ability in Kindergarten.
Child Development. 78(2), 647 - 663.

http://www.sciam.com/article.cfm?articleID=90377FAE-E7F2-99DF-3A1204FC5F2BF0F7

Students who believe intelligence can be developed perform better

Research with 12-year-olds has found that, although all students began the study with equivalent achievement levels in math, over a two year period, those who believed that intelligence was malleable increasingly did better than those who believed their intelligence was fixed. Another study found that, when students showing declines in their math grades were taught that intelligence could be increased, they reversed their decline and showed significantly higher math grades than others who weren’t taught that.

[1123] Blackwell, L. S., Trzesniewski K. H., & Dweck C S.
(2007).  Implicit Theories of Intelligence Predict Achievement across an Adolescent Transition: A Longitudinal Study and an Intervention.
Child Development. 78(1), 246 - 263.

http://www.eurekalert.org/pub_releases/2007-02/sfri-swb013107.php

Implicit stereotypes and gender identification may affect female math performance

Relatedly, another study has come out showing that women enrolled in an introductory calculus course who possessed strong implicit gender stereotypes, (for example, automatically associating "male" more than "female" with math ability and math professions) and were likely to identify themselves as feminine, performed worse relative to their female counterparts who did not possess such stereotypes and who were less likely to identify with traditionally female characteristics. Strikingly, a majority of the women participating in the study explicitly expressed disagreement with the idea that men have superior math ability, suggesting that even when consciously disavowing stereotypes, female math students are still susceptible to negative perceptions of their ability.

[969] Kiefer, A. K., & Sekaquaptewa D.
(2007).  Implicit stereotypes, gender identification, and math-related outcomes: a prospective study of female college students.
Psychological Science: A Journal of the American Psychological Society / APS. 18(1), 13 - 18.

http://www.eurekalert.org/pub_releases/2007-01/afps-isa012407.php

Reducing the racial achievement gap

And staying with the same theme, a study that came out six months ago, and recently reviewed on the excellent new Scientific American Mind Matters blog, revealed that a single, 15-minute intervention erased almost half the racial achievement gap between African American and white students. The intervention involved writing a brief paragraph about which value, from a list of values, was most important to them and why. The intervention improved subsequent academic performance for some 70% of the African American students, but none of the Caucasians. The study was repeated the following year with the same results. It is thought that the effect of the intervention was to protect against the negative stereotypes regarding the intelligence and academic capabilities of African Americans.

[1082] Cohen, G. L., Garcia J., Apfel N., & Master A.
(2006).  Reducing the Racial Achievement Gap: A Social-Psychological Intervention.
Science. 313(5791), 1307 - 1310.

Fitness and childhood IQ indicators of cognitive ability in old age

Data from the Scottish Mental Survey of 1932 has revealed that physical fitness contributed more than 3% of the differences in cognitive ability in old age. The study involved 460 men and women, who were tested using the same cognitive test at age 79 that they had undergone at age 11. Physical fitness was defined by time to walk six meters, grip strength and lung function. Childhood IQ was also significantly related to lung function at age 79, perhaps because people with higher intelligence might respond more favorably to health messages about staying fit. But physical fitness was more important for cognitive ability in old age than childhood IQ. People in more professional occupations and with more education also had better fitness and higher cognitive test scores at 79.

[770] Deary, I. J., Whalley L. J., Batty D. G., & Starr J. M.
(2006).  Physical fitness and lifetime cognitive change.
Neurology. 67(7), 1195 - 1200.

http://www.eurekalert.org/pub_releases/2006-10/aaon-fac100306.php

Black-white IQ gap has narrowed

Data now available suggests that Black Americans have gained an average of .18 IQ points a year on White Americans from 1972 to 2002 for a total gain of 5.4 IQ points.

[929] Dickens, W. T., & Flynn J. R.
(2006).  Black Americans reduce the racial IQ gap: evidence from standardization samples.
Psychological Science: A Journal of the American Psychological Society / APS. 17(10), 913 - 920.

http://www.eurekalert.org/pub_releases/2006-09/afps-big091206.php

Does IQ drop with age or does something else impact intelligence?

As people grow older, their IQ scores drop. But is it really that they lose intelligence? A study has found that if college students had to perform under conditions that mimic the perception deficits many older people have, their IQ scores would also take a drop.

[234] Gilmore, G. C., Spinks R. A., & Thomas C. W.
(2006).  Age effects in coding tasks: componential analysis and test of the sensory deficit hypothesis.
Psychology and Aging. 21(1), 7 - 18.

http://www.eurekalert.org/pub_releases/2006-05/cwru-did050106.php

Smarter kids may live longer

A prospective study that recruited 897 individuals who scored 135 or higher on the Stanford-Binet IQ test in 1922 has found that higher IQs were associated with longevity, with the survival advantage leveling off after a childhood IQ of 163. The association was independent of childhood social position (as measured by father’s occupation). The study confirms earlier research suggesting an association between IQ and mortality, and provides the new finding of where the cut-off point (when high IQ no longer brought additional health benefits) appears — the cutoff of 163 was much higher than expected. Suggested reasons for the association (all of which may well be valid) include: greater tendency to adopt healthy habits and avoid bad ones; increased probability of better jobs; better skills for managing their health and the health-care system.

[690] Martin, L. T., & Kubzansky L. D.
(2005).  Childhood Cognitive Performance and Risk of Mortality: A Prospective Cohort Study of Gifted Individuals.
Am. J. Epidemiol.. 162(9), 887 - 890.

http://health.yahoo.com/news/126478

Growing up in a chaotic home may impair child's cognitive development

An association between disorganized, noisy and cramped homes and lower childhood intelligence has been observed before, but the reasons for the association have never been clear. Now a study of some 8000 3- and 4-year-old twins has perhaps disentangled the variables, and has found that chaos had an influence on cognitive skills independent of socioeconomic status. The findings also suggest that when the environment is more stressful, intelligence is more likely to be constrained by genes.

[570] Petrill, S. A., Pike A., Price T., & Plomin R.
(Submitted).  Chaos in the home and socioeconomic status are associated with cognitive development in early childhood: Environmental mediators identified in a genetic design.
Intelligence. 32(5), 445 - 460.

http://www.newscientist.com/news/news.jsp?id=ns99996323

Early music instruction raises child’s IQ

A new study confirms earlier research supporting the benefits of early music instruction. The study involved 144 children, 6 years old at the start of the study. They were given free weekly voice or piano lessons at the Royal Conservatory of Music. Another group of 6-year-olds was given free training in weekly drama classes, while a fourth group received no extra classes during the study period. Before any classes were given, all the children were tested using the full Weschler intelligence test. At the end of the school year (their first school year), the children were retested. All had an IQ increase of at least 4.3 points on average (a consequence of going to school). Children who took drama lessons scored no higher than those who had no extra lessons, but those who took music lessons scored on average 2.7 points higher than the children who did not take music lessons. Those in the drama group did however show substantial improvement in adaptive social behavior.

[1009] Schellenberg, E. Glenn
(2004).  Music lessons enhance IQ.
Psychological Science: A Journal of the American Psychological Society / APS. 15(8), 511 - 514.

http://www.sciencentral.com/articles/view.htm3?article_id=218392326

Knowledge-based IQ test predicts work performance as well as school

A meta-analysis of 127 studies supports the view that the Miller Analogies Test (MAT) — a knowledge-based test used for admissions decisions into U.S. graduate schools as well as in hiring and promotion decisions in the workplace since 1926 — is predictive of performance in both the academic and workplace environments. Specifically, MAT was a valid predictor of seven of the eight measures of graduate student performance, five of the six school-to-work transition performance criteria, and all four of the work performance criteria. MAT is assumed to measure “g”, the oft-debated “general intelligence” factor.

[1109] Kuncel, N. R., Hezlett S. A., & Ones D. S.
(2004).  Academic Performance, Career Potential, Creativity, and Job Performance: Can One Construct Predict Them All?.
Journal of Personality and Social Psychology. 86(1), 148 - 161.

Support for "general intelligence" factor

Researchers into intelligence and memory have always concentrated on verbal abilities — for the good reason that they are considerably easier to test. New research suggests that strong visuospatial skills and working memory may be at least as good as verbal skills and working memory as indicators of general intelligence. The study, involving 167 subjects, found a clear relationship between being good at complex visuospatial tasks, and being good at tasks involving the so-called “central executive” (which coordinates tasks, sets goals, etc). The study lends support both to the view that intelligence has both discrete components and a general aspect, and that this “general intelligence” may be related to executive functioning.

[1152] Miyake, A., Friedman N. P., Rettinger D. A., Shah P., & Hegarty M.
(2001).  How are visuospatial working memory, executive functioning, and spatial abilities related? A latent-variable analysis.
Journal of Experimental Psychology. General. 130(4), 621 - 640.

http://www.eurekalert.org/pub_releases/2001-12/apa-npo121001.php

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Why a select group of seniors retain their cognitive abilities

December, 2011
  • Comparison of the brains of octogenarians whose memories match those of middle-aged people reveals important differences between their brains and those of cognitively-normal seniors.

A certain level of mental decline in the senior years is regarded as normal, but some fortunate few don’t suffer from any decline at all. The Northwestern University Super Aging Project has found seniors aged 80+ who match or better the average episodic memory performance of people in their fifties. Comparison of the brains of 12 super-agers, 10 cognitively-normal seniors of similar age, and 14 middle-aged adults (average age 58) now reveals that the brains of super-agers also look like those of the middle-aged. In contrast, brain scans of cognitively average octogenarians show significant thinning of the cortex.

The difference between the brains of super-agers and the others was particularly marked in the anterior cingulate cortex. Indeed, the super agers appeared to have a much thicker left anterior cingulate cortex than the middle-aged group as well. Moreover, the brain of a super-ager who died revealed that, although there were some plaques and tangles (characteristic, in much greater quantities, of Alzheimer’s) in the mediotemporal lobe, there were almost none in the anterior cingulate. (But note an earlier report from the researchers)

Why this region should be of special importance is somewhat mysterious, but the anterior cingulate is part of the attention network, and perhaps it is this role that underlies the superior abilities of these seniors. The anterior cingulate also plays a role error detection and motivation; it will be interesting to see if these attributes are also important.

While the precise reason for the anterior cingulate to be critical to retaining cognitive abilities might be mysterious, the lack of cortical atrophy, and the suggestion that super-agers’ brains have much reduced levels of the sort of pathological damage seen in most older brains, adds weight to the growing evidence that cognitive aging reflects clinical problems, which unfortunately are all too common.

Sadly, there are no obvious lifestyle factors involved here. The super agers don’t have a lifestyle any different from their ‘cognitively average’ counterparts. However, while genetics might be behind these people’s good fortune, that doesn’t mean that lifestyle choices don’t make a big difference to those of us not so genetically fortunate. It seems increasingly clear that for most of us, without ‘super-protective genes’, health problems largely resulting from lifestyle choices are behind much of the damage done to our brains.

It should be emphasized that these unpublished results are preliminary only. This conference presentation reported on data from only 12 of 48 subjects studied.

Reference: 

Harrison, T., Geula, C., Shi, J., Samimi, M., Weintraub, S., Mesulam, M. & Rogalski, E. 2011. Neuroanatomic and pathologic features of cognitive SuperAging. Presented at a poster session at the 2011 Society for Neuroscience conference.

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Repetition is behind our improved memory for emotional events

December, 2011

A new study concludes that positive events tend to be remembered better than negative, but the more important finding is that being repeatedly reminded of the event is the main factor behind improved memory for emotional experiences.

Certainly experiences that arouse emotions are remembered better than ones that have no emotional connection, but whether negative or positive memories are remembered best is a question that has produced equivocal results. While initial experiments suggested positive events were remembered better than negative, more recent studies have concluded the opposite.

The idea that negative events are remembered best is consistent with a theory that negative emotion signals a problem, leading to more detailed processing, while positive emotion relies more heavily on general scripts.

However, a new study challenges those recent studies, on the basis of a more realistic comparison. Rather than focusing on a single public event, to which some people have positive feelings while others have negative feelings (events used have included the OJ Simpson trial, the fall of the Berlin Wall, and a single baseball championship game), the study looked at two baseball championships each won by different teams.

The experiment involved 1,563 baseball fans who followed or attended the 2003 and 2004 American League Championship games between the New York Yankees (2003 winners) and the Boston Red Sox (2004 winners). Of the fans, 1,216 were Red Sox fans, 218 were Yankees fans, and 129 were neutral fans. (Unfortunately the selection process disproportionately collected Red Sox fans.)

Participants were reminded who won the championship before answering questions on each game. Six questions were identical for the two games: the final score for each team, the winning and losing pitchers (multiple choice of five pitchers for each team), the location of the game, and whether the game required extra innings. Participants also reported how vividly they remembered the game, and how frequently they had thought about or seen media concerning the game.

Both Yankee and Red Sox fans remembered more details about their team winning. They also reported more vivid memories for the games their team won. Accuracy and vividness were significantly correlated. Fans also reported greater rehearsal of the game their team won, and again, rehearsal and accuracy were significantly correlated.

Analysis of the data revealed that rehearsal completely mediated the correlation between accuracy and fan type, and partially mediated the correlation between vividness and fan type.

In other words, improved memory for emotion-arousing events has everything to do with how often you think about or are reminded of the event.

PTSD, for example, is the negative memory extreme. And PTSD is characterized by the unavoidable rehearsal of the event over and over again. Each repetition makes memory for the event stronger.

In the previous studies referred to earlier, media coverage provided a similarly unavoidable repetition.

While most people tend to recall more positive than negative events (and this tendency becomes greater with age), individuals who are depressed or anxious show the opposite tendency.

So whether positive or negative events are remembered better depends on you, as well as the event.

When it comes down to it, I'm not sure it's really a helpful question - whether positive or negative events are remembered better. An interesting aspect of public events is that their portrayal often changes over time, but this is just a more extreme example of what happens with private events as well — as we change over time, so does our attitude toward those events. Telling friends about events, and receiving their comments on them, can affect our emotional response to events, as well as having an effect on our memory of those events.

Reference: 

[2591] Breslin, C. W., & Safer M. A.
(2011).  Effects of Event Valence on Long-Term Memory for Two Baseball Championship Games.
Psychological Science. 22(11), 1408 - 1412.

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Memory genes vary in protecting against age-related cognitive decline

November, 2011

New findings show the T variant of the KIBRA gene improves episodic memory through its effect on hippocampal activity. Another study finds the met variant of the BDNF gene is linked to greater age-related cognitive decline.

Previous research has found that carriers of the so-called KIBRA T allele have been shown to have better episodic memory than those who don’t carry that gene variant (this is a group difference; it doesn’t mean that any carrier will remember events better than any non-carrier). A large new study confirms and extends this finding.

The study involved 2,230 Swedish adults aged 35-95. Of these, 1040 did not have a T allele, 932 had one, and 258 had two.  Those who had at least one T allele performed significantly better on tests of immediate free recall of words (after hearing a list of 12 words, participants had to recall as many of them as they could, in any order; in some tests, there was a concurrent sorting task during presentation or testing).

There was no difference between those with one T allele and those with two. The effect increased with increasing age. There was no effect of gender. There was no significant effect on performance of delayed category cued recall tests or a visuospatial task, although a trend in the appropriate direction was evident.

It should also be noted that the effect on immediate recall, although statistically significant, was not large.

Brain activity was studied in a subset of this group, involving 83 adults aged 55-60, plus another 64 matched on sex, age, and performance on the scanner task. A further group of 113 65-75 year-olds were included for comparison purposes. While in the scanner, participants carried out a face-name association task. Having been presented with face-name pairs, participants were tested on their memory by being shown the faces with three letters, of which one was the initial letter of the name.

Performance on the scanner task was significantly higher for T carriers — but only for the 55-60 age group, not for the 65-75 age group. Activity in the hippocampus was significantly higher for younger T carriers during retrieval, but not encoding. No such difference was seen in the older group.

This finding is in contrast with an earlier, and much smaller, study involving 15 carriers and 15 non-carriers, which found higher activation of the hippocampus in non-T carriers. This was taken at the time to indicate some sort of compensatory activity. The present finding challenges that idea.

Although higher hippocampal activation during retrieval is generally associated with faster retrieval, the higher activity seen in T carriers was not fully accounted for by performance. It may be that such activity also reflects deeper processing.

KIBRA-T carriers were neither more nor less likely to carry other ‘memory genes’ — APOEe4; COMTval158met; BDNFval66met.

The findings, then, fail to support the idea that non-carriers engage compensatory mechanisms, but do indicate that the KIBRA-T gene helps episodic memory by improving the hippocampus function.

BDNF gene variation predicts rate of age-related decline in skilled performance

In another study, this time into the effects of the BDNF gene, performance on an airplane simulation task on three annual occasions was compared. The study involved 144 pilots, of whom all were healthy Caucasian males aged 40-69, and 55 (38%) of whom turned out to have at least one copy of a BDNF gene that contained the ‘met’ variant. This variant is less common, occurring in about one in three Asians, one in four Europeans and Americans, and about one in 200 sub-Saharan Africans.  

While performance dropped with age for both groups, the rate of decline was much steeper for those with the ‘met’ variant. Moreover, there was a significant inverse relationship between age and hippocampal size in the met carriers — and no significant correlation between age and hippocampal size in the non-met carriers.

Comparison over a longer time-period is now being undertaken.

The finding is more evidence for the value of physical exercise as you age — physical activity is known to increase BDNF levels in your brain. BDNF levels tend to decrease with age.

The met variant has been linked to higher likelihood of depression, stroke, anorexia nervosa, anxiety-related disorders, suicidal behavior and schizophrenia. It differs from the more common ‘val’ variant in having methionine rather than valine at position 66 on this gene. The BDNF gene has been remarkably conserved across evolutionary history (fish and mammalian BDNF have around 90% agreement), suggesting that mutations in this gene are not well tolerated.

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Dealing with math anxiety

November, 2011

A new study shows that some math-anxious students can overcome performance deficits through their ability to control their negative responses. The finding indicates that interventions should focus on anticipatory cognitive control.

Math-anxiety can greatly lower performance on math problems, but just because you suffer from math-anxiety doesn’t mean you’re necessarily going to perform badly. A study involving 28 college students has found that some of the students anxious about math performed better than other math-anxious students, and such performance differences were associated with differences in brain activity.

Math-anxious students who performed well showed increased activity in fronto-parietal regions of the brain prior to doing math problems — that is, in preparation for it. Those students who activated these regions got an average 83% of the problems correct, compared to 88% for students with low math anxiety, and 68% for math-anxious students who didn’t activate these regions. (Students with low anxiety didn’t activate them either.)

The fronto-parietal regions activated included the inferior frontal junction, inferior parietal lobule, and left anterior inferior frontal gyrus — regions involved in cognitive control and reappraisal of negative emotional responses (e.g. task-shifting and inhibiting inappropriate responses). Such anticipatory activity in the fronto-parietal region correlated with activity in the dorsomedial caudate, nucleus accumbens, and left hippocampus during math activity. These sub-cortical regions (regions deep within the brain, beneath the cortex) are important for coordinating task demands and motivational factors during the execution of a task. In particular, the dorsomedial caudate and hippocampus are highly interconnected and thought to form a circuit important for flexible, on-line processing. In contrast, performance was not affected by activity in ‘emotional’ regions, such as the amygdala, insula, and hypothalamus.

In other words, what’s important is not your level of anxiety, but your ability to prepare yourself for it, and control your responses. What this suggests is that the best way of dealing with math anxiety is to learn how to control negative emotional responses to math, rather than trying to get rid of them.

Given that cognitive control and emotional regulation are slow to mature, it also suggests that these effects are greater among younger students.

The findings are consistent with a theory that anxiety hinders cognitive performance by limiting the ability to shift attention and inhibit irrelevant/distracting information.

Note that students in the two groups (high and low anxiety) did not differ in working memory capacity or in general levels of anxiety.

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