In my view, the most that can be said for reading is that reduces the possibility that you might go outside and break a leg playing sports. Certainly that is a valuable contribution to civilization, but some researchers have made the further claim that reading boosts intelligence. Will the intelligence boosting dream never die? Take one large bright pill, follow a convoluted set of mental exercises and then, wham, arise to the soaring heights of genius, (and eventually fall from grace) as in that heart-rending classic, Flowers for Algernon.
The latest paper on this matter is far more crafty than that.
Stuart J. Ritchie, Timothy C. Bates and Robert Plomin (2014) Does Learning to Read Improve Intelligence? A Longitudinal Multivariate Analysis in Identical Twins From Age 7 to 16. Child Development. 24 JUL 2014 DOI: 10.1111/cdev.12272
The authors eschew get-bright-quick schemes and concentrate on whether humble reading ability precedes later increases in intelligence in identical twins. Their core argument is that if one identical twin reads better than their identical twin brought up in the same household, then the difference is unlikely to be their identical genetics, so more likely to be a specific (not shared) environmental effect of some sort. Whatever it is, if they can show it boosts intelligence, then this would be a proven example of the environmental influence of reading ability (due to teaching techniques perhaps) on intelligence, and a possible pathway to boosting intelligence through education.
Here is their plan: Using a longitudinal monozygotic (MZ) twin differences design, we test whether twins who—for purely environmental reasons—acquire better reading skills than their co-twin show improvements in intelligence, and whether these associations are found across five waves of testing. Such a finding would have implications for educational interventions, and may also provide a partial answer to the important question of why children within a family have very different intelligence test scores, despite sharing factors such as genes, parental education, parental personality, and socioeconomic status (Plomin, 2011; Plomin & Daniels, 1987).
I hope that, so far, all this makes sense, but since the authors are clever monkeys the plot gets thicker, and there are many paths in infinite space to be tracked down before clarity ensues. Here is Fig 3 showing the significant associations:
The finding is that Reading Ability Difference at age 7 is related to IQ Difference at ages 9 and 10, and that Reading Ability Difference at age 10 is related to IQ Difference at age 12 and Reading Ability Difference at age 12 is related to IQ difference at age 16. It certainly looks as if the twin with the better reading goes on to get better intelligence test results a few years later.
Table 1 shows the raw results for the particular tests used. The sample sizes, means and standard deviations for the IQ subtests are shown. These tests were administered individually by telephone, using a booklet mailed to the twins’ home prior to testing
(Petrill, Rempell, Dale, Oliver, & Plomin, 2002). Stuart Ritchie has kindly sent me the distributions for the 7 year olds, and it looks like they did less well on Similarities than the other tests, but this must be seen in the context of their being raw scores, not standardised scores:
All the scores in the descriptive table are raw scores, but when they go into the model, they are controlled for age and sex and standardized (the model has no mean structure, just correlations). The tests used in TEDS are not the exact ones from Wechsler - they’re often based on those tests, but with some extra items added to make them harder for the older age groups. I’m not sure on what basis this was done, but obviously the decision was made at some point that they had to keep scaling up the difficulty rather than using the standard, normed tests.
The problem with this, as hinted above, is that you can’t use any kind of latent growth curve approach (like we do regularly in the Lothian Birth Cohort data) - because the tests aren’t the same at each time point, you can’t compare means. It’s harder to do this with kids of course, who are getting better with age rather than worse. Elliot Tucker-Drob, in his Texas Twin sample, always makes sure that there’s one identical test that overlaps two of the waves, so that there’s something to anchor the growth curve. I’m not actually certain how this works in practice, but in the next few years I suppose his Texas Twins papers will be appearing and we’ll find out...
The authors conclude: The present study provided compelling evidence that improvements in reading ability, themselves caused purely by the non-shared environment, may result in improvements in both verbal and nonverbal cognitive ability, and may thus be a factor increasing cognitive diversity within families (Plomin, 2011). These associations are present at least as early as age 7, and are not—to the extent we were able to test this possibility—driven by differences in reading exposure. Since reading is a potentially remediable ability, these findings have implications for reading instruction: Early remediation of reading problems might not only aid in the growth of literacy, but may also improve more general cognitive abilities that are of critical importance across the life span.
Of course, at the beginning of this essay I may have been a little too harsh in my bleak evaluation of the benefits of reading. This was probably because I did not think that reading increased the power of the intellect. I felt that the size of the cognitive engine remained the same. However, education may act as a gearbox, applying a set of skills to maximise the use of the engine.
In his great poem of AD 835 “A mad poem addressed to my nephews and neices” Po Chu-I begins with a couplet on this very matter:
The World cheats those who cannot read; I, happily, have mastered script and pen
So, it may be that lack of reading cheats children of (some) intelligence.