Why do they all look the same?

Okay, so I met this girl yesterday who wanted to buy my Social Psych book... we exchanged numbers and whatever... and so we decided to meet this morning around 9 before her class in front of the Library. Ofcourse i get there at 8:59... right in the nick of time. Okay... it's pretty high traffic in the school around that time... and yeah i forgot to mention she is Oriental/Asian... whatever... and I couldn't for the life of me remember what she looked like! So i called her... she didn't pick up... i was like oh great! So i decided to wait... hoping she would find me instead.. and then I thought maybe if I saw her I would be able to recognize her... but they all looked the same or similar enough... and i kept thinkin every other girl was her :S Needless to say... i still have the book...