It has been an general opinion among people that ambidexterity is associated with increased brain activity. This assumption is based on the fact that the right hemisphere of the brain controls the left hand and vice versa.
Though the fact about brain activity, and parts of brain controlling different body functionalities is true, ambidexterity doesn't really help to improve brain activity. Moreover, based on a few studies that are conducted with right handers, left handers and ambidextrous people, the ambidextrous people had scored less in memory and logical reasoning.
So, why is activating different parts of brain doesn't help in improving brain activity? The reason being the confusion between multihandedness and ambidexterity. A multi handed person, say Sachin Tendulkar, who writes with left hand, and plays cricket with right hand, has different functionalities of brain activating from different hemispheres of brain. This would still maintain their brain hemispheres to be asymmetric.
At the same time, for an ambidextrous person, the same functionalities would be activated by both hemispheres, which would result in mirroring of brain activity. This would lead to confusions, while deciding which hand is better suited for a particular task.
More than that, it also affects the critical decision making and logical reasoning power of the brain due to mirroring effect. Hence, ambidexterity is considered to be more of an disadvantage.
Though there hasn't yet been any scientific or statistical proof for ambidexterity to improve or deteriorate the brain functionality, from evolutionary behavior, it can be observed that ambidexterity is the least favored. Hence, it wouldn't be a bad conclusion to state that ambidexterity doesn't improve the functionality of brain.
