Hi,
I am a grad school at a pretty big research university, in the clinical psych dept. I can tell you that i know exactly what you're going through (well, at least I think I do), because I remember being at your stage and worrying about exactly the same things. My experience has told me that IT DOESN'T REALLY MATTER! I didn't work for people who do the same research as I'm doing now, and I don't think my advisor cared, nor did the advisor at the other program I got into. Also, I see other people in my program and know what they did before they came, and I think, "what the hell was I so worried about?!?!?" As long as you show you are a serious applicant and that you are really interested in psychology and in research when you interview, it should be ok. It's important that your GPA and GRE scores are good but the rest sort of falls into place on its own.
In our program, this is how it goes:
First, the school get TONS of applications. What they do first is look at all the students who fit above a certain cut (this is why GPA and GRE are important). Then they look at letters of recommendations (also VERY important). I didn't have a letter from a very well known person--I just had good letters. Then, I believe it's up to each advisor to choose how many applicants they want to interview and extend invites to. This depends on the needs of the lab -- how many students they already have, how many they need, how they want the build of their lab to be like (females and males, research interests--but not experience, just interests).
What's really important after you've made the cut is just that the school is a "good fit" .I think a lot of times, this depends on your personality. really! once you get an interview, it's really your personality that counts, and how the other grad students in the lab view you. Your research interests are important too, but this can be demonstrated through ways other than your previous research job.
Ironically, I was an RA for 3 years before grad school, and I think that taking more time off and learning more before grad school has actually hurt me. The program wants to shape you according to their views. They don't want someone who knows the stuff well enough to argue with them or ask too many smart-assed questions. They just want to do their research and hopefully graduate some good researchers as well. If you show you like research and you are interested in their research, that's all you need (after GPA and GRE scores). They know you don't have the experience -- that's why you're going to grad school! The reason I think people say you should be an RA before grad school is, I think, so that they know you have seen the world of research and still want to go into it, because it's rough world to be in. However, I must say that there are plenty of students in my cohort who only did one year or who didn't RA at all before grad school.
I know I'm rambling on, but the upshot is that you need good GPA and GRE scores, good letters of recommendation, and a high level of enthusiasm.
Also, if you are worried about getting at least a little experience with anxiety d/o's, one thing you can do is try to ask your new boss if you could do some sort of personal project on the side that is related to their interests but also incorporates anxiety disorders. Always remember there is a lot of comorbidity in psych. Addictions is def related to anxiety! So is depression and most disorders. See if they will let you do a paper on the side with them that talks about anxiety within their relm of research. Or, see if your boss knows others in the field who do anxiety disorders and would be willing to talk with you. Making contacts is always good, and they may have more input.
So, I hope I have helped and eased some of your worries. Let me know if you have any specific questions!