"Only if it turns out that reality is actually nothing more than a holographic illusion created by the interplay of subatomic particles on a vast two-dimensional membrane."
This article covers a subject that has been deemed non-canon by either the author or the Back to the Future licensees, and thus should not be taken as a part of the "real" Back to the Future universe.
Marty McFly: "Didn't they give you some kind of digital watch when you were done with all that brainwashing?"
Jennifer Parker: "The Citizen Plus watch? I won't get one of those until another five or six treatments."
— Marty McFly and his girlfriend Jennifer Parker discussing the watch.
The Citizen Plus wristwatch was a device invented sometime during the 1986G timeline. It was given to those who had gone through at least five Citizen Plus Treatments.
For the most part, the watch's functions were the same as any other. It could be set to letters as well as numbers, however, and when the combination X:11 was entered, the watch would immediately render the user blank and open to suggestion, creating a "zombie" under the control of whoever had entered the code. The idea was Edna Strickland Brown's, as her idea of a perfect Hill Valley would be a society of docile, content and easily controlled people.
In order to keep her husband in the dark about the unhappy state of Hill Valley's citizens, Edna Strickland approached Biff Tannen, the first Citizen Plus, and entered X:11 into his watch. She proceeded to order him to knock out George McFly and take the tapes he had that provided evidence of the miserable citizens. Later, after being released from his trance, Marty McFly put him under the watch's spell again and told him to get the tapes back. Biff then dived down the decycling bin to get them, discovering the room underneath, the room where Edna had been residing. She ordered Biff to restrain Marty, who had followed him, while she destroyed the tapes. Marty eventually broke Biff out of his watch's spell – and that of the Citizen Plus Program – by pointing out to him all the things he had once enjoyed: beer, cigars, the license plate of his car and Playboy magazines.