Having been an engineer responsible for installing the most vast array of unusual electronic systems in to aircraft, I have only on one ocasion had an ocurrence of RFI. It was an IDME interfearing with a GPS RX due to proxcimity of the antennas. This is of course a well known problem now, and is usually avoided at installation.
The number of computers, and telephones, and radio transmitters that I have installed ain't small, and it has been my experience that very little upsets aircraft systems.
My experience has seen all sorts of electronic equipment used at all sorts of locations in the most electronically complex of aircraft and I have never seen a systems performance effected. Laptop and mobile telephone in the cockpit or the E&E bay, both in use, no problem. Digital imaging computers in aircraft with hills hoists strung around them to pulse massive em pulses in to the ground, no problem.
What I see surrounding the EMI/RFI claims of interference to aircraft systems is a whole lot of anecdotal evidence, linking system malfunctions to a coincidence. eg. the autopilot malfunctioned, and there was a laptop turned on in the cabin nowhere near the INS or the autopilot, but since the laptop was there it must have caused the malfunction!!
As for the study, from what I know of EMI RFI on aircraft trhough experience, I would love to get a copy of the methods, if anyone can point me in the right direction, please do!!