Why are display pictures important in the internet profiles?

Answering Question 3 only:

When I search for language exchange partners, scrolling down a list, I'd click those without a pic. Of course, if the pic is a cute doggy or kitty or cartoon character, it'd also make me clicking into the profile.

even i change my dp frequently. i donno what others want to show through their dpics...but in my case, i always try 2 keep my dp in such a way dat my dp would b unique among all my frnds' pics. dats y i never keep my posture as my dp. 

may i know what do you want to show through your profile display picture???(as you initiated the discussion).

I guess we are looking for something attrective to us. It could be a beautiful face, a funny picture of a dog, or anything else, that can catch our attention and impress us in some positive way. Smiling faces are more attrective than sad, good quality of photo also makes us like it ( and it's owner) more. We are humans and our brain and emotions play a great role in our choises. These choices could seem to us not so rational, but it is just part of our behavior as human beings.

well i think the picture is something that allows other people to see you as a person. if the person doesn't have one, it doesn't mean he is "empty" lol, but still you won't find him as interesting as the other ones. you might as well can make an opinion about that person about his picture.

@ Rummy: Of course, my handsome personality.. lol... well, I have the same dp since May-2009 and never though of changing it as yet..!!

By the way, your dp is unique even in this post ;) I am interested to see how do you change it..!!

1) I don't like to change my dp  because I like people to recognize myself quickly. I think I'll change only if I feel that picture is not representing me any more.

2) I want to show myself  as I really am.

3) I, personally, like a simple photo of the person and don't like cartoons characters, animals and so on, but of course I accept them as part of another personality.

How do we change our profile picture?

Pure narcisstic reasons, I guess.

You have control over what you want to show and don't in your profile pic. In a pic, unlike in reality, you can choose how to present yourself, possibly how you want others to perceive you----pretty, smart, cool etc.

I don't upload a pic of my face on the internet for everyone to see, because of security reasons. I'm neither a public figure nor a celebrity, and I hope to keep it that way.

Maybe things would be different if I were a teacher or something on this site for business opportunities. In that case, perhaps there might be the merit of showing my face since a personal pic would more connect with students.