I've found the closer I get to target, the more I can notice the small amounts on my body.
When I had more to lose, I never really noticed it from week to week, and I'm a slow loser, but other people would notice more than I.
Now I seem to really tell when I'm up a lb - I feel heavier, can feel it in my clothes etc. Conversely, when I'm doing well and am sure I'm on for a loss, I can feel that too. I just feel lighter and clothes fit better. Partly psychological I'm sure, but I am sure now that I'm lighter each lb is more noticable!