SPEARMAN’S LAW OF DIMINISHING RETURNS: INVESTIGATION ON LARGE-SCALES RUSSIAN SAMPLES

  • K. V. Sugonyaev Institute of Psychology of Russian Academy of Sciences, Moscow, Russian Federation
  • Y. I. Radchenko Military Academy of General Staff, Moscow, Russian Federation
Keywords: Spearman’s “Law of Diminishing Returns” (SLODR), the differentiation hypothesis, general cognitive ability, g factor, psychometric characteristics

Abstract

The reduction of average correlations among cognitive tests in groups of individuals of above-average IQ was invented by C. Spearman (1927) and now is known as Spearman’s “Law of Diminishing Returns” (SLODR). Although many studies also founded that inter-correlations between subtests decreased from low to high ability groups, several empirical investigations have challenged the SLODR. InRussiasimilar studies didn’t carry out by now. We investigated the presence of SLODR in large-scaled dataset consisted of sample of 11335 applicants for joining to military institutes (mean age 18.42±1.29 years). The subjects were tested with the same battery of 10 ability tests. SLODR was assessed (tested) by dividing the sample into low/high ability groups based on the total score. In order to account for criticism ofMurrayet. al. (2013), test scores in each half-sample were transformed to normalized stens separately to equate variability and minimize skewness. Our findings were fully consistent with SLODR-based predictions, thus refuting suggestions about artifactual genesis of this phenomenon. To cross-validate this result analysis was repeated on second analogous sample after exclusion of all applicants older than 19 years (N = 11934, mean age = 17.91±0.47). And again, all indexes accounted were consistent with SLODR. The results indicate that SLODR effects are emerged on the level of group ability factors, are quite reproducible and relatively independent from test’s g-loading and psychometric properties of their scores. Hypotheses are suggested to account for possible reasons of negative outcomes in some earlier studies.

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Author Biographies

K. V. Sugonyaev , Institute of Psychology of Russian Academy of Sciences, Moscow, Russian Federation
associate member
Y. I. Radchenko , Military Academy of General Staff, Moscow, Russian Federation
Head of the Scientific Practice Centre of the Military Academy of General Staff
Published
2019-04-17
How to Cite
Sugonyaev, K., & Radchenko, Y. (2019). SPEARMAN’S LAW OF DIMINISHING RETURNS: INVESTIGATION ON LARGE-SCALES RUSSIAN SAMPLES. Psychology. Psychophysiology, 11(1), 5-21. https://doi.org/10.14529/psy180101
Section
Methodological and theoretical issues of psychology