I try not to judge people by their age. But the more people you meet who fit the stereotype of a certain age category, the harder it is to truly put the preconceived notions aside. I fit into an age category of people that really annoy the crap out of me most times. And yet, I've made a new friend recently who is my same age and is surprisingly mature and decent. And yet, most other people in my age group are nincompoops.
It all depends, I'm a sophomore and I think I'm pretty mature, not to be conceited or anything. I just notice I don't do a lot of stupid things that some other sophomores, juniors, or seniors would do. I care about my grades, future, etc. So yes, I think younger people can be more mature than an adult.
I don't judge people by their age at all. The only thing I judge them by is how mature they are, as in not acting childish, and how intelligent they are. And I think that's the way it should be.
I don't really judge people by their age although it does give me an impression. But, the main thing that really gets me is their intelligence, maturity, and character. It doesn't matter (to me) whether they are 1 or 75, it depends on the person that they really are inside.
I don't judge people by their age at all. I even try to speak to people a lot younger than me like adults.
I'd fall under the really annoying category. As I see it, age doesn't make so much of a difference as other's preconceived bias (e.g. some adults I can have decent conversations with, and they'll actually listen to/value my opinion, whereas others just use the whole "Oh-you're-too-young-to-understand" excuse to ignore me), maturity, and intellect. I try not to judge people by age (especially those younger than me, because I remember being at a particular age and finding it extraordinarily annoying that others looked down on me due to age), but of course I probably have an inherent/instant mental bias formed as soon as I see someone. (After all, humans judge others for a "first impression" within the first 3 seconds of seeing someone.) I think maturity matures significantly more than age, because I know kids my age that I avoid at all costs because they are, quite frankly, extremely immature/annoying, yet I also know kids who are technically years younger than me that have a much clearer perception/understanding of the world.