Abstract: Woodley et al. (2013) cite declines in simple reaction time as evidence of dysgenesis. In this paper it is conceded that these declines are strong evidence for a dysgenic trend. However, declines in g cannot be inferred from reaction time declines alone.
Woodley et al. (2013) are quite correct that the existence of a secular decline in reaction time suggests dysgenesis. However, the secular decline in reaction time is probably a poor quantification, per se, of the exact dysgenesis rate. Woodley (2012) argues that the Flynn effect may be caused by increasing specialization in cognitive abilities. If specialization has truly increased, one would expect to see a secular decline in certain such abilities. These abilities are probably, for the most part, not measured on typical g-loaded tests (Lynn, 1998 gives the example of farming ability), but it is nevertheless to be expected that some g-loaded tests will show a secular decline. It may be responded that reaction time’s shared variance with g is wholly genetic (Woodley et al. cite Rijsdijk et al., 1998 on this matter) and therefore changes in specialization will have a minor impact. However, even if the environmental influences on reaction time are different from those on IQ, there may still be considerable environmental influences. Moreover, reaction time influences mortality rates (Deary & Der, 2005). Declining reaction time independent of g fits into Woodley’s (2012) life-history model because there would be less pressure to develop a mortality-mediating ability in a less environmentally harsh environment. It should be noted as well that even though simple reaction time shows little or no training effect (Kida et al., 2005), there may be other processes that decrease simple reaction time, such as imprinting (Armstrong & Woodley, under review).
While Woodley et al. extract declines in g from the declines in reaction time (given a .54 correlation), simply multiplying the decline in reaction time by the g-loading is not sufficient to establish a decline in g (cf. Dickens & Flynn, 2001 for discussion of a similar issue). Using a similar procedure on IQ tests for the Flynn effect would imply high g gains (say, if performance on a test with a g-loading of 0.8 has increased by a d of 1, this procedure would imply that g has increased by a d of 0.8). However, the Flynn effect is not on g (Woodley, 2011, 2012a, 2012b; te Nijenhuis & van der Flier, 2013).
A number of similar declines (approximately 1 SD since the Victorian era) on other highly g-loaded tests or abilities would corroborate Woodley et al.’s dysgenesis estimate. To the best of my knowledge, though, there are few tests that have shown a secular decline; the SATs have, but the population has grown increasingly representative (e.g., Williams and Ceci, 1997; Sailer, 2011a, 2012). Piagetian tasks show a decline (Shayer et al., 2007), and if the decline in g estimated from secular trends in Piagetian tasks is comparable to the decline in g estimated from secular trends, this would corroborate a 1 SD dysgenesis estimate. Likewise, if the decline in IQ among wealthy countries that are no longer experiencing the Flynn effect (e.g., Sundet et al., 2004) was similar to the decline measured using reaction time, Woodley et al.’s estimate would be validated.
Finally, it should be noted that a g decline of 1 SD is difficult to believe (cf. Charlton, 2013; Flynn, 1987; Guha, 2001 for discussion of a similar issue). A community with average levels of g 1 SD higher than modern populations would be supermen. Ashkenazi Jews, who are a tremendously successful ethnic group, appear to have IQs around 110 (e.g., Cochran et al., 2005; Lynn, 2011; Sailer, 2011b). Hence even the most intellectually successful ethnic group would have IQs five points lower than the Victorians, if Woodley et al. are correct. This process of devolution is made quite incredible by the fact that it is hypothesized to have occurred in only 130 years (Cochran, 2012).
Armstrong, E., and Woodley, M. A. The rule-dependence model explains the commonalities between the Flynn effect and IQ gains via retesting. Under review.
Charlton, B. (2013). "Extraordinary claims require extraordinary evidence" - with respect to the claim of intelligence decline since Victorian times. Retrieved from http://charltonteaching.blogspot.com/2013/05/extraordinary-claims-require.html.
Cochran, G., et al. (2006). Natural history of Ashkenazi intelligence. Journal of Biosocial Science, 38, 659-693.
Cochran, G. (2012). The long and short of it. Retrieved from http://westhunt.wordpress.com/2012/11/04/the-long-and-short-of-it/.
Deary, I., and Der. G. (2005). Reaction time explains IQ’s association with death. Psychological Science, 16, 64-69.
Dickens, W., and Flynn, J. R. (2001). Heritability estimates versus large environmental effects: The IQ paradox resolved. Psychological Review, 108, 346-369.
Flynn, J. R. (1987). Massive IQ gains in 14 nations: What IQ tests really measure. Psychological Review, 101, 179-191.
Guha, S. (2001). A philosopher’s paradise––in inspired lunacy. Retrieved from http://www.amazon.com/review/R2ER6NZI1H2WJ/ref=cm_aya_cmt?ie=UTF8&ASIN=0631224262#wasThisHelpful.
Rijsdijk, F. V., et al. (1998). The genetic basis of the relation between speed-of-information-processing and IQ. Behavioural Brain Research, 95, 77-84.
Lynn, R. (1998). In support of the nutrition theory. In U. Neisser (Ed.), The rising curve: Long-term gains in IQ and related measures (pp. 207-215). Washington, D. C.: American Psychological Association.
Lynn, R. (2011). The Chosen People. Augusta, GA: Washington Summit Publishers.
Sailer, S. (2011a). SAT score changes by race since 1996. Retrieved from http://isteve.blogspot.com/2011/09/sat-score-changes-by-race-since-1996.html
Sailer, S. (2011b). Lynn on the Jews: Yes, it’s intelligence –– but there’s something else too. Retrieved from http://www.vdare.com/articles/lynn-on-the-jews-yes-it-s-intelligence-but-there-s-something-else-too.
Sailer, S. (2012). SAT and ACT: How hard are they scraping the bottom of the barrel and are they finding any diamonds in the rough? Retrieved from http://isteve.blogspot.com/2012/10/sat-and-act-how-hard-are-they-scraping.html
Shayer, M., et al. (2007). Thirty years on – a large anti-Flynn effect? The Piagetian test Volume & Heaviness norms 1975–2003. British Journal of Educational Psychology, 77, 25-41.
Sundet, J.M., et al. (2004). The end of the Flynn effect? A study of secular trends in mean intelligence test scores of Norwegian conscripts during half a century. Intelligence, 32, 349-362.
te Nijenhuis, J., & van der Flier, H. (in press). Is the Flynn effect on g?: A meta-analysis. Intelligence.
Williams, W. M., and Ceci, S. J. (1997). Are Americans becoming more or less alike? Trends in race, class, and ability differences in intelligence. American Psychologist, 52, 1226-1235.
Woodley, M. A. (2011a). Heterosis doesn’t cause the Flynn effect: A critical examination of Mingroni (2007). Psychological Review, 118, 689-693.
Woodley, M. A. (2012a). The social and scientific temporal correlates of genotypic intelligence and the Flynn effect. Intelligence, 40, 189–204.
Woodley, M. A. (2012b). A life history model of the Lynn-Flynn effect. Personality
and Individual Differences, 53, 152–156.
Woodley, M.A., et al. (in press) Were the Victorians cleverer than us? The decline in general intelligence estimated from a meta-analysis of the slowing of simple reaction time. Intelligence.