Rising IQ scores prompt reinvestigation of gender differences in cognitive abilities

Although we believe intelligence to be a heritiable trait (in that the genetic contribution of one's parents might bestow on a child part of their intellectual potential), there is undoubtably an influence of the environment and early socialisation experiences that are influenced by cultural beliefs and educational experiences. These experiences are partly shaped by the contribution of caregivers, family and teachers as a child progresses through the educational system. And there have certainly been changes in those educational environments rom the local, state, and national level education systems of most nations. It might seem reasonable, therefore, that we might see rises in the level of reading literacy, and with the cheap and ubiquitous nature of technology in our modern culture we might also see rises in numerical and scientific literacy as well. But not necessarily intelligence, as defined by psychometric IQ.


So it seems surprising, therefore, to conider that IQ scores are rising. This phenomenom, known as the 'Flynn effect' after the researcher James Flynn who made the discovery, is robust and has been observed for both developed and developing nations. It amounts to a gain on average of about three IQ points per decades. It is for this reason that tests of psychometric intelligence such as the WAIS for adults and WISC for children must be periodically refined and updated so as to prove a reliable and valid discriminator of individual ability. This process, referred to as norming, involves recruiting large demographically representative samples of the general population so that an individual's performance can be measured relative to the population from which he or she is drawn. Test norms can quickly become outdate, which places an onus on those who administrate psychological to use the most recent version of the test available to produce an evalation of an individual that is meaningful and valid.

There are various reasons mooted for the global rise in IQ scores from better nutrition and medical care, better access to schools and to learning, etc. A full discussion of the debate is beyond the scope of this blogpost, but it rasies some interesting and thoughtprovoking implications. Are we all, as a planet, growing smarter across the generations at a uniform rate or are some of us advancing at a faster rate?

In his latest book, James R. Flynn (2012) evaluates this proposition and comes to some startling conclusions. His ata suggest that women may be gaining on men at a faster rate over the decades. If so, the implication would be that gender gaps in cognitive abilities will shrink over time and that many of the claims of sex differences in the literature may not hold true in the future. We live in interesting times.


References
Flynn, J. R. (2012). Are we getting smarter? : Rising IQ in the twenty-first century. Cambridge; New York: Cambridge University Press.

Selection bias in sampling

Selection bias in sampling

   When evaluating research, critical analysis skills are essential in determining whether the decision that has been drawn is valid for a given sample, and most particularly when deciding whether the finding from a given study can be generalised to the wider population. Its something that many people either don't consider, or choose to ignore. Particularly when the conclusion drawn suits your ideological world-view. Especially then.

   Take for example the classic scientific scenario of a controlled trial. One group is given the treatment (which may be a drug, it may be a psychological intervention, or a different environment and set of stimuli). One group does not, we refer to this as the control group. If we compare the performance of the two groups at some future point in time, then any difference that is observed can be inferred to be the direct cause of the treatment. If we randomly allocate particpants to either the treatment and control, and both groups are equivilent at the beginning, then the treatment must be the cause!

Simple enough so far? Now imagine that instead of a randomized control trial, you allow the participants to choose which group they'd like to be in. For example, a group of clinically depressed people are offered the choice of an proven an efective anti-depressant, or some psychological counselling. We find that the group receiving the drug shows greater improvement than the counselling group. Does that mean that antidepressants work better than counselling?
Well it kind of depends.

Even when the groups are equivilent in age, gender mix, sociodemographic factors, etc. the problem is that the two groups might differ on some unobserved characteristics. Do you think that people who have a preference for medication might have some preconceived notions about its effectivness? Conversely, those who opt for counselling might have greater faith in psychology than psychiatry. When the participants choose, you cannot assume that unobserved characteristics won't come into place.

Let's illustrate it with another example. Selection bias is the problem facing educators and cognitive researchers in evaluating the influence of single-sex schooling over traditional coeducational schooling. In a recent consensus statement published in Science titled "The pseudoscience of single-sex schooling", Halpern et al., (2011) argue that the gold standard for evaluating single-sex schooling is a randomized controlled trial. But as critics of the article argue, who could imagine forcing such a choice on parents and children? A toss of a coin - heads you are coeducational, tails you go to a single-sex school. All we can do is look at the abundance of evidence that suggests making gender salient (such as emphasing the difference between boys and girls, or placing children in a same-sex learning environment) emphasises sex-typing and has the opposite of the intended effect. It makes boys and girls more sex-typed, rather than less.


Halpern, D. F., Eliot, L., Bigler, R. S., Fabes, R. A., Hanish, L. D., Hyde, J. S., et al. (2011). The pseudoscience of single-sex schooling. Science, 333(6050), 1706-1707. doi: 10.1126/science.1205031

     While the intention of this blog will be to provide useful and insightful commentary about the field of applied psychology (and from time to time, science in general), its main goal is to help me organise my thoughts and notes about the field as I continue my PhD.  PhD's are tricky beasts, and can easily morph off-topic (in computer science terms, feature creep). While I'm studying gender psychology, its very much a cross-disciplinary field with influences from education, cognitive psychology, psychometrics, and cross-cultural studies.

     So sometimes I'll use this blog to write a short piece about these fields, either for my own personal interest or perhaps with vague notions of turning it into a peer-reviewed publication output at some distant point in the future. Us academic types love publication outputs, even if they're in the most obscure and least read journal on the planet. Especially if they're in an obscure and less read journal. Why? because they're usually subject to less scrutiny, making it easier to get some outrageous claim or theory into the body of literature. There's a bias in science literature to accepting anything - even if it is far-fetched, untested, and on occasion indefensible - if its published in a peer-reviewed journal. Because peer-review weeds out anything dodgy, and can then be cited ad infinitum by others. And often by yourself in future publications. Caveat emptor, and all that.