This actually isn't all that surprising. Consider autists, for example. People have always noted their ability to intensely focus on a single thing through a time frame that can be as large as their own lifetime, while only casually drawing the line between that and their correlation with high IQ. If instead of focusing your cognition on emotions, sociability, or anything but what you're currently doing really, do you think you'll do better on that task? Of course you will. In reverse, multitasking always lowers competence in task performance.
This is further amplified by how their mind, born with a natural affinity to focus on details without spending resources on anything else (or rather, reasoning it being better not to spend on anything else), changes to accommodate their subject of interest and their conduct. Focus more, and it follows your brain will focus better, a positive feedback loop that gives autists their brains and Buddhist monks their control over their brain's processing.
Bottom line, doing this will make you much more proficient at whatever your goal is, but it will also make you much more autistic, though at that point you will see it as superiority.