Brutha,
The study you refer to does indeed indicate no generalized positive correlation linking ambidexterity and cognitive abilities. However, it is important to look at the source of data and research methods to determine context with such studies.
The authors reexamined data from studies done with children where the children were required to do 3 very short tasks...
- Tick as many squares as possible on a printed sheet with the left hand, repeating this procedure with the right (both in a 1-minute time period)
- Bouncing and catching a ball 10 times (making note of which hands were used)
- Timing the picking up of 20 matches (making note of which hands were used)
Therefore, while this study may point to a lack of latent positive relationships between ambidexterity and cognitive ability in children performing minimal general tasks, it does not directly examine relationships in tasks requiring years of study and practice. However, the authors of this particular study do mention another study in relating ambidexterity and cognitive ability in 52 pianists while sight reading where a positive correlation is found.
On the matter of extrapolating behavior from particular geniuses (Einstein and company) to the general public...
I believe it is important to know whether certain forms of mental exercise, practiced over a period of years can produce genius effects in the general public. I have contemplated my own intuitive thoughts and studied both academic and nonacademic resources on the matter for over 2 decades. I have also personally observed anecdotal results of certain ways of thinking with over 2500 private music students (from all walks of life) during this time. As a result, I am convinced it is possible for most people to learn genius behavior with sufficient training and practice.
It will take many formal studies for the academic community to determine reliable conclusions on the matter, but research has to start somewhere. Therefore, it is appropriate to ask questions and hypothesize the possibility of whether such relationships exist. This is one of the reasons I conducted my PhD dissertation and contemplated related questions in my research. It is also a reason why the academic community validated my research through publication.
Mike