Elsevier Logo It is commonly assumed that the brain’s left hemisphere is vital for processing qualitative ‘categorical’ information, while the right side is engaged in quantitative ‘metric’ processing. Well, if the following piece of information is to be believed, then this is not true. A latest study claims that the left side of the brain is important for metric processing and the right for categorical information.

The study was conducted to analyze the complications experienced by 55 patients who recently underwent an operation to remove a brain tumor from either the left or right side of the brain. Participants were shown a series of images of a dot inside an upright or tilted frame and were made to reproduce its position inside an identical upright frame. This task possibly requires mental rotation of the image. It was noted that patients with tumors in the right parietal or in the left prefrontal cortices seemingly made too many errors than other patients.

Both the groups supposedly behaved rather differently from each other. The right parietal patients purportedly placed the mark in the right position with respect to a corner. They apparently chose the wrong corner much often that the other patients. Cognitive neuroscientist Tim Shallice and colleagues presume that subjects prefer the wrong corner more times that the other patients. The left prefrontal patients allegedly got the corner right, but were otherwise highly inaccurate in their responses.

Patients with tumors of the right parietal cortex unable to process categorical spatial information and perform the mental rotation probably got the corner right with extreme inaccuracy in their responses. A left prefrontal tumor may have led to difficulties in the setting up of the specific program within the brain which was critical to organize the sequence of operations required to carry out the task.

The study was published in the February 2011 issue of Cortex.