NoteHandedness and intellectual achievement: An even-handed look
Section snippets
Method
The New Zealand IQ Test was developed by writing 160 items across various dimension, and then administering these to a pilot group along with the Ravens Matrices and parts of the WISC (verbal comprehension, perceptual organization, working memory, and processing speed). Sixty items were chosen to maximize the relations between the total IQ score from the different tests, with six items in each of the following dimensions of intelligence: language ability (meanings, anagrams), numerical ability
Results
IQ was estimated for all 1355 respondents, ranged from 85 to 135, with a mean of 99.6 and a standard deviation of 15.4. The correlation between the New Zealand IQ Test and the total Raven was .67, and with the WAIS was .69. The estimates of reliability exceeded .90. Principal component analysis yielded a single component with an eigenvalue greater than 1.0, and loadings on the component are shown in Table 1. Each subtest therefore contributed approximately equally to a general factor.
Of the
Discussion
Despite the small number of respondents describing themselves as ambidextrous, the results provide support for the finding that there is a dip in intellectual performance among the ambidextrous relative to left- and right-handers (Crow et al., 1998), and also confirm earlier evidence that there is little if any difference between left- and right-handers (Hardyck et al., 1976).
Although the survey was not designed specifically to test for the effects of handedness, a number of considerations
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The asymmetrical brain
2021, Encyclopedia of Behavioral Neuroscience: Second EditionThe relation between mental rotation and handedness is a consequence of how handedness is measured
2019, Brain and CognitionFitness costs and benefits associated with hand preference in humans: A large internet study in a Dutch sample
2018, Evolution and Human BehaviorHandedness and cognitive ability: Using meta-analysis to make sense of the data
2018, Progress in Brain ResearchCitation Excerpt :Another possibility is that the effects of this reorganization would be disadvantageous, as different cognitive functions would compete for the same neural space resulting in “cognitive crowding” and hence reduced cognitive ability (Lidzba et al., 2006). Other theoretical accounts attempt to explain the cognitive deficits not of left-handers, but of individuals lacking consistent handedness or having weak laterality patterns (e.g., Corballis et al., 2008, Crow et al., 1998, but see also Mayringer and Wimmer (2002) who found no such deficits). Corballis et al. (2008) suggested the possibility that reporting to write with either hand could represent a manifestation of intellectual confusion.
Right-handers have negligibly higher IQ scores than left-handers: Systematic review and meta-analyses
2018, Neuroscience and Biobehavioral ReviewsCitation Excerpt :In the case of performance measures, some studies use a large number of manual tasks (e.g., Witelson et al., 2006, 12 items) when others use just one to three items (e.g., Calnan and Richardson, 1976). In addition, while in some cases handedness is treated as a continuous variable (e.g., Crow et al., 1998; Nettle, 2003; Resch et al., 1997), in other studies handedness is treated as a categorical variable, with distinct categories based either on a binary (left- and right-handers) or a three-way (or more) handedness classification (left-, mixed- and right-handers) (e.g., Annett and Manning, 1989; Corballis et al., 2008, respectively). Moreover, different cut-off criteria have been used to separate handedness groups.
Motor behavior reflects reduced hemispheric asymmetry in the psychosis risk period
2016, Schizophrenia Research