Intelligence, Volume 26, Number 4

Rodgers, J. L. (1998). A critique of the Flynn Effect: Massive IQ gains, methodological artifacts, or both? Intelligence, 26, 337-356.

The Flynn Effect proposed by J. R. Flynn is reviewed and evaluated. Even in the presence of a skeptical and critical scrutiny of the effect, it appears that there is more than just methodological artifact to be explained. But the acceptance of the effect has been too quick. The proper explanations for the effect will not be meaningful until the nature of the effect is much better understood than it is now. Six questions are raised that have not been adequately answered. Two criticisms of the logic underlying the Flynn Effect are presented--one showing that even if IQ and SAT are highly correlated, their secular means will not necessarily track one another; the second showing that results by Flynn are as consistent with a changing IQ variance as with a changing mean. The second of these is empirically evaluated with a reanalysis of a subset of the sources of Flynn 1984 data. Finally, 10 research strategies and designs are suggested that would help us better understand the effect. The critique is developed with the goal of clarifying the nature, meaning and causes of the Flynn Effect. The author hopes that the critique will stimulate both healthy skepticism about the Flynn Effect and careful research into its actual causes.

Deary, I. J., MacLennan, W. J., & Starr, J. M. (1998). Is age kinder to the initially more able?: Differential ageing of a verbal ability in the Healthy Old People in Edinburgh Study. Intelligence, 26, 357-375.

Studies that examine whether there is differential age-related decline in intelligence test scores according to initial cognitive status, social class and education are reviewed. The authors tested the differential ageing hypothesis which states that decline in ability scores over time will be lower in those with superior mental ability, more education and higher social class at the time of original testing. 387 healthy old people were tested at baseline and followed up 4 yrs later. The National Adult Reading Test (NART) was administered on both occasions. NART-estimated IQ fell by a mean of 2.1 points over 4 yrs. Subjects in higher social class categories had higher NART scores overall, and had smaller NART decrements over 4 yrs. Ex-professional and -secretarial groups fell by a mean of 1.4 points in this period, vs 3.2 points for skilled manual, semi-skilled and unskilled groups. In addition, those who fell more in NART were older, were less educated, and had lower NART scores at baseline. In summary, those with higher baseline ability, in higher social class groups, with more education and who are younger are relatively protected from decline in this verbal ability with age. Possible mechanisms of differential decline in verbal intelligence with age are discussed.


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