Traditionally, research on language lateralization is conducted in psychological labs, but recently the use of smartphones as test devices is on the rise. Here, a team of researchers from the Biopsychology lab and the Bergen fMRI group used a Apple iOS app to investigate the heritability of language lateralization assessed with the dichotic listening task, as well as the heritability of cognitive control processes modulating performance in this task. Overall, 103 families consisting of both parents and offspring were tested with the non-forced, as well as the forced-right and forced-left condition of the forced attention dichotic listening task, implemented in the iDichotic smartphone app, developed at the University of Bergen, Norway. The results indicate that the typical right ear advantage in the dichotic listening task shows weak and non-significant heritability. In contrast, cognitive factors, like attention focus and cognitive control showed stronger and significant heritability. These findings indicate a variable dependence of different aspects of a cognitive function on heritability and implicate a major contribution of non-genetic influences to individual language lateralization.

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Ocklenburg, S., Ströckens, F., Bless, J.J., Hugdahl, K., Westerhausen, R., Manns, M., Investigating heritability of laterality and cognitive control in speech perception, Brain and Cognition, 2016, 109: 34-39.