There are a few things that are posited to be correlated, here:
1. Multitasking and poor cognitive performance
2. multitasking and poor memory
3. poor memory and poor cognitive performance (obviously).
Which way does causation run?
My guess is that it goes like this: Multitasking (optional) –> poor memory –> poor cognitive performance
being able to focus on a problem for long periods of time DEFINES intelligence. Controversial, non?