I heard that someone named Harry Kahne in 60s or 70s did a literal multitasking. Does this mean that, with practice, you can push the limit up to 4 or 5(I'm not sure how many he insisted)?
On second thought, I guess you can with practice anyway..
Suppose we have a interface, just a connector, nothing more, nothing less.
Can't we just connect a memory chip or some artificial network whatever and see how the brain cope with those? (ignoring whether there's such a connector or not. oh and any ethical problem put aside also)