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Handedness, footedness, eyedness and earedness in the Colorado Adoption Project
Author(s) -
Saudino K.,
McManus I. C.
Publication year - 1998
Publication title -
british journal of developmental psychology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.062
H-Index - 75
eISSN - 2044-835X
pISSN - 0261-510X
DOI - 10.1111/j.2044-835x.1998.tb00916.x
Subject(s) - psychology , developmental psychology , cognitive psychology
Dominance of hand, foot, ear and eye was examined in the Colorado Adoption Project (CAP) to examine whether previously reported familial trends in lateralization are the result of genetic or environmental processes. Despite a relatively large sample size for an adoption study, and evidence that the measures of lateralization were typical of those found in other studies, no significant familial trends were found in any of the measures of direction of lateralization. Nevertheless, effects found for handedness were of a similar magnitude to that shown elsewhere in the literature and it was concluded that this adoption study alone did not have sufficient statistical power to partition variance into genetic and environmental components. Other studies taken alone are also likely to suffer from the same problem, and therefore the question is only likely to be definitively resolved by combining data from a number of studies by means of meta‐analysis. Degree of lateralization was also examined and no evidence was found for familial trends in handedness, footedness, eyedness or earedness. Power analysis suggested that the present data were sufficient to detect effects similar to those previously reported for handedness and that this result was best interpreted as a true failure of replication of familial association for handedness. The study is also the first to examine degree of eyedness, earedness and footedness, and finds no evidence for familial associations.