| 1. |
- Coyle, Thomas R., et al.
(author)
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The heritability of ability tilts
- 2023
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In: Personality and Individual Differences. - : Elsevier. - 0191-8869 .- 1873-3549. ; 213
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Journal article (peer-reviewed)abstract
- Tilts arise from within-subject differences in performance between two distinct cognitive ability measures (e.g., verbal minus quantitative). These are independent of general cognitive ability (GCA) and are likely a function of differential investment of time and other resources into the cultivation of one ability, at the expense of another. There is some debate about the meaning and measurement of tilts among psychometricians, but a body of research is emerging demonstrating that these are predictive of real-world outcomes independent of GCA. An open question concerns the heritability of tilts. Since nearly all phenotypic individual differences are heritable, tilts, if substantive, should not be an exception. It was found that tilts are modestly heritable (after controlling for participant age and residual correlations with GCA) in three samples (US children, Georgia Twin Study; Swedish adults, Swedish Twin Registry; US adults, MIDUS II). AE models better fit the tilt data in all but one case (Verbal - Reasoning, in the GTS, where an ACE model better fit the data). Comparatively large (non-shared) environmentalities were noted in all cases, potentially consistent with models predicting a role for niche-picking and experience-producing-drive dynamics in generating tilts. A Wilson-like effect was observed when the tilt heritabilities in the GTS were compared with their equivalent parameters in the other two (older) samples. The finding that tilts exhibit non-zero heritability in different age ranges and in two countries strengthens their external validity, and weakens claims that they are measurement artifacts, as predisposing genetic and environmental factors are part of their nomological network.
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| 2. |
- Dutton, Edward, et al.
(author)
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The intelligence and personality of Finland's Swedish-speaking minority
- 2016
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In: Personality and Individual Differences. - : Elsevier BV. - 0191-8869 .- 1873-3549. ; 97, s. 45-49
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Journal article (peer-reviewed)abstract
- There is evidence that Finland's Swedish-speaking minority (Finland-Swedes) may have a distinct intelligence-personality profile from the Finnish-speaking Finns (Finns). We test this through an examination of the two groups' PISA (Programme of International Student Assessment) scores (which assesses representative samples of 15 year olds from OECD countries) and their personality scores, drawing upon a representative Finnish sample. We found Finland-Swedes to have slightly lower average intelligence. However, when controlling for gender and age, the Finland-Swedes score significantly higher on Conscientiousness, Extraversion and Emotional Stability. Overall, we found a Jensen Effect whereby most of the personality differences between the two groups could be attributed to the General Factor of Personality (GFP), which reflects the shared variance of lower-order personality traits. The GFP is assumed to reflect general social effectiveness.
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| 3. |
- Madison, Guy, et al.
(author)
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Secular Slowing of Auditory Simple Reaction Time in Sweden (1959-1985)
- 2016
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In: Frontiers in Human Neuroscience. - : Frontiers Media. - 1662-5161. ; 10
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Journal article (peer-reviewed)abstract
- There are indications that simple reaction time might have slowed in Western populations, based on both cohort- and multi-study comparisons. A possible limitation of the latter method in particular is measurement error stemming from methods variance, which results from the fact that instruments and experimental conditions change over time and between studies. We therefore set out to measure the simple auditory reaction time (SRT) of 7,081 individuals (2,997 males and 4,084 females) born in Sweden 1959-1985 (subjects were aged between 27 and 54 years at time of measurement). Depending on age cut-offs and adjustment for aging related slowing of SRT, the data indicate that SRT has increased by between 3 and 16 ms in the 27 birth years covered in the present sample. This slowing is unlikely to be explained by attrition, which was evaluated by comparing the general intelligence x birth-year interactions and standard deviations for both male participants and dropouts, utilizing military conscript cognitive ability data. The present result is consistent with previous studies employing alternative methods, and may indicate the operation of several synergistic factors, such as recent micro-evolutionary trends favoring lower g in Sweden and the effects of industrially produced neurotoxic substances on peripheral nerve conduction velocity.
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| 4. |
- Woodley of Menie, Michael A, et al.
(author)
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The association between g and K in a sample of 4246 Swedish twins : a behavior genetic analysis
- 2015
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In: Personality and Individual Differences. - : Elsevier. - 0191-8869 .- 1873-3549. ; 74, s. 270-274
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Journal article (peer-reviewed)abstract
- Whereas the heritability of general intelligence (g) is very well documented, there are relatively few reports of the heritability of life history speed (K). Moreover, the correlation between g and K is of great theoretical significance. Here, we examine the heritabilities of g and K in a sample of 2123 complete Swedish twin pairs, as well as looking for evidence of common genetic variance between the two. We find a significant albeit very small correlation between relatively strong measures of g (the Wiener Matrizen Test) and K (the Mini-K; r = .03, p < .05). Controlling for attenuation by reliabilities and imperfect validity using validity generalization increased the correlation to rho = .05 (p < .05). There was no significant common additivity between g and K, however path elimination in behavior genetic structural equations modeling suggests that the small common variance is nonetheless likely to stem from shared additive genetic influences rather than from environmental influences. The implications of this are discussed. Our new estimate of the heritability of the life history in the Swedish population is a particularly significant result, as the heritability of life history speed has never before been established in non-US samples.
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