On the mediating effects of pregnancy and birth stress events on the relation between lateral preferences and cognitive functioning in healthy school-aged children.

If the pathological left-handedness theory is valid, left-handed people who also experienced pregnancy and birth stress events (PBSEs) would especially be expected to deviate from the cognitive norm (rather than left-handers in general). This hypothesis was tested in a large sample of healthy children (aged 6.6-15.9 years). Multiple cognitive abilities were assessed, including verbal fluency and working memory. Children with a left lateral preference who also experienced a PBSE did not deviate from the cognitive norm. Age was positively associated with all cognitive measures, and mean level of parental education strongly affected verbal fluency functioning.