Well, partially it depends on your starting weight. For example, if you started at 130, then you'd probably see a 9 pound loss pretty easily. If you started at 300, then it probably wouldn't really show.
Then it depends on your body, on how you carry the weight and where it comes off of first. And on how realistic your body image is.
For me personally, I started off at 220 and I'm now about 175. That's about a 45 pound loss and I still have trouble seeing it. Oh, my clothes are way too big on me (I can't even wear my old jeans, they fall off!) AND when I see pictures of myself from last year, I am amazed at how fat I look. Plus, everyone tells me that they are amazed at how much I've lost, even people who didn't know I was trying to lose weight. But when I look in the mirror, I just don't see much difference.
I think that's because for a long time I wouldn't admit to myself how big I had gotten. At my heaviest, I'd see pics of myself and think "I'm not that big! I just take awful pictures!" I'd see larger women and think "wow, see? I'm not so bad." I think my body now is finally about what I thought it was then. Does that make any sense?