MDWigs: It's interesting to note that the characters in the series always refer to this simply as “A.T. Field”. Here is the only place where we are told what the “A.T.” actually stands for. (Of course, in external sources, it's also stated that “A.T. Field” = “Absolute Terror Field.”)
thewayneiac: Something that needs to be buried along with the "Four Barons of Hell" is the idea that "A.T. Field" is a genuine psychological term used to descibe the barrier separating patients of autism from reality. After a search that included browsing psychology bulletin boards and newsgroups, I have yet to find one mention of A.T. Field in any non-Eva related source. I've come to the conclusion that this is yet another one that was pulled out of someone's posterior.