http://www.emdr.com/briefdes.htm
EMDR has been rather reduced in this thread to something too basic, imo. Tapping or eye movement are quite common elements. Who cares what, if it works?
It allows for more adaptive information to be processed and linked to a traumatic memory (for instance.)
Yes, I agree, if you don't think it will help, or don't wish it to, or believe that it won't, then it won't help.
http://www.emdr.com/q&a.htm#q16 Some theory behind it.
It is touted as excellent for trauma work. I wish I could do it and be done with my PTSD

sigh oh well.