This 2013 human study added to the existing understanding of how our brain hemispheres work.

“The main contribution of our study is to demonstrate, at a whole-brain scope, the qualitative differences between the hemispheres in their within- and between-hemisphere interactions. The correlations with behavioral ability really hammer this distinction home, since one needed to use the appropriate metric – that is, segregation versus integration – to see these correlations.

..the left hemisphere showing a preference to interact more exclusively with itself, particularly for cortical regions involved in language and fine motor coordination. In contrast, right-hemisphere cortical regions involved in visuospatial and attentional processing interact in a more integrative fashion with both hemispheres.

The degree of lateralization present in these distinct systems selectively predicted behavioral measures of verbal and visuospatial ability, providing direct evidence that lateralization is associated with enhanced cognitive ability.”

A paraphrase of this last sentence may be that our overall cognitive ability is enhanced when we develop the functional specializations of both brain hemispheres.

http://www.pnas.org/content/110/36/E3435.full “Two distinct forms of functional lateralization in the human brain”