Left-Handedness and Cognitive Deficit

Abstract

Intellectual and performance measures were taken on 7688 school children tested on three behavioral measures of handedness and one measure of eyedness. Test results were compared against all combinations of handedness and eyedness and against a measure of socio-economic level. No relationships of any kind were found. Comparisons of the present results are made against 33 studies concerned with possible deficits associated with left-handedness. The results of the present study combined with a review of the majority of studies on deficit and handedness strongly suggest that the hypothesis of no difference in intellectual and cognitive performance between right- and left-handed subjects can be accepted as true.

Ecological Threat and Psychological Variation

“…Cultural transmission provides a relatively quick means for adapting to a wide range of ecologies and environmental changes. An explanation based upon wholly cultural processes is also compatible with evidence documenting relatively rapid changes in cultural values (i.e., changes observed over the course of a generation or two) associated with immigrant populations who migrate from ecologies of high disease threat to ecologies with substantially lower disease threat (e.g., Hardyck, Petrinovich, & Goldman, 1976). Humans are also equipped with cognitive tools and biases which are compatible with a cultural transmission explanation, such as perceptual hypervigilance to cues connoting the presence of threat, selective communication about threat, and social learning of avoidant responses to threat (Cook & Mineka, 1990;Öhman, Flykt, & Esteves 2001;Schaller & Conway, 1999).…”

Exploring gene–culture interactions: insights from handedness, sexual selection and niche-construction case studies

“…Left-handers are found at lower frequencies in societies that associate it with clumsiness, evil, dirtiness or mental illness, such as some middle and far eastern countries (Harris 1980;Corballis 1991). Studies of school children in China and Taiwan report only 3.5 and 0.7 per cent used their left hand for writing, compared with a 6.5 per cent estimate for Oriental school children living in the USA (Hardyck et al 1976;Teng et al 1976;Hung et al 1985).…”

The economic consequences of being left-handed: some sinister results

“…Firstly, there are numerous findings that left-handedness is associated with various undesirable outcomes such as low cognitive ability (e.g. Hardyck, Petrinovich, & Goldman 1976, McManus & MascieTaylor 1983 as well as a number of unusual and sometimes pathological conditions. For example a higher incidence of left handedness is found amongst groups with a history of alcoholism, autism, criminality, depression, homosexuality, immune diseases, psychosis and schizophrenia to mention but a few 6 .…”