How can we measure and quantify concentration or focus? For example, if I were to say:
"If you do Activity X while using Y, you will be more concentrated than if you were using Z"
How can I quantify that? And what tests should I do to actually prove that statement? Examples are appreciated.
Background I am trying to build some different technology products and I want them to help the user stay more focused than they would using a competitor product of the same kind. The only research I've done so far was to build some interfaces and ask the user how they feel.