As strange as this sounds, I think this question is very strongly weighted by the age of the participants. Teenagers, young adults, and even those in 25-, are fairly regarded as being more chatty than those 30-35+. By the later years, you've settled more into a routine and have your own actual life to worry about. In 25-, most young adults are still exploring the world, and as such -- want to get to know people. At my ripe old age of 20, I'd jump for the opportunity to talk to every random person on the bus/train/plane that I could. Once I'm 40, I'm sure I'll want to sit and read my book, or play my computer. There's nothing inherently wrong, and I'm not trying to imply that old people are boring.. just take into consideration the age of the participants. I wouldn't mind someone random falling asleep on my shoulder (although it would be rather difficult, as I'm 6'6"). However, when I'm 40, I probably WILL mind. The older the person gets, the less likely talking to them is a good idea. Ask ANY 16 year old girl a question and then ask a 36 year old woman the same question.. you'll see the difference in willingness to talk..
