A new study by Nielsen and colleagues (2013) examined this by using functional magnetic resonance imaging (fMRI). The authors obtained data from fMRI reports of 1011 individuals between the ages of 7 and 29. These fMRI reports revealed the individuals’ resting brain activity.
If the resting brain was more active in one side relative to the another, this would suggest that some people are “left-brained”, while others are “right-brained”. The results, however, did not support this common assumption. Therefore, no brain side (hemisphere) is more dominant over the other, when the brain rests.
The study does not contradict the finding that some people are more creative, while others are more logical. It is just that creative and logical abilities cannot be attributed to superior activity of the right-brain and left-brain, respectively. The brain works in its entirety.
Despite the fact that there is no evidence for left and right-brain personalities, some brain functions are biased (i.e., laterialized) towards the left and right hemisphere of the brain. This means that certain parts of the brain process certain tasks.
At times, the brain may show superior activity in one side over the other, depending on the task that is being conducted at that time. For example, in right-handed individuals, language processing is thought to be laterialized to the left side of the brain, whereas visuospatial processing is laterialized to the right side of the brain (Nielsen et al., 2013).