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The evolutionary origins of functional cerebral asymmetries in humans: Does lateralization enhance parallel processing?

Hirnstein, M.; Hausmann, M.; Güntürkün, O.

Authors

M. Hirnstein

O. Güntürkün



Abstract

Functional cerebral asymmetries (FCAs) are a fundamental principle of brain organization in many species. However, little is known about why they have evolved. Since FCAs are such a widespread phenomenon they seem to constitute an evolutionary selective advantage. According to a prominent hypothesis, an asymmetric brain should be associated with advantages in parallel processing, i.e. doing two tasks simultaneously. The strong version of this hypothesis implies that lateralized, instantaneous and complementary tasks are performed more efficiently with a highly lateralized brain. Using a visual half-field procedure, we wanted to test this strong version of the parallel-processing hypothesis in humans. Thirty-two participants (17 women, 15 men) were investigated. First, we assessed the degree of lateralization in a face/non-face and a word/non-word discrimination task favouring the right and left hemisphere, respectively. Based on a median split, subjects were divided into a rather symmetric and a rather asymmetric group. Then, all participants completed both tasks simultaneously. The results revealed that the rather symmetrically organized participants outperformed asymmetric participants in accuracy and response times. Hence, the strong version of the parallel-processing hypothesis has to be revised.

Citation

Hirnstein, M., Hausmann, M., & Güntürkün, O. (2008). The evolutionary origins of functional cerebral asymmetries in humans: Does lateralization enhance parallel processing?. Behavioural Brain Research, 187(2), 297-303. https://doi.org/10.1016/j.bbr.2007.09.023

Journal Article Type Article
Publication Date Mar 5, 2008
Deposit Date Nov 5, 2012
Journal Behavioural Brain Research
Print ISSN 0166-4328
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 187
Issue 2
Pages 297-303
DOI https://doi.org/10.1016/j.bbr.2007.09.023
Keywords Functional cerebral asymmetries, Evolution, Parallel processing, Dual task, Humans.