Where I work people are on the telephone most of the time. Some when talking can only concentrate on that call and are completely oblivious to everything else around - if the fire alarm went off there is no guarantee they would notice it they are that uni-focussed. At the other extreme are people who happily listen on the phone, browse the internet, doodle, pass messages to others, write emails and get involved in other conversations - it's just different ways peoples brains work. My wife wonders why my son and I play guitar while we are watching the TV (the answer is because the two things don't conflict for me or him) or read and watch things. Just how we are. It's not a male:female thing as usually depicted though as my wife and I are back to front on this.

There was an interesting comment that (I think) Barry Finn made on a thread about accompaniment some while back that being a good accompanist perhaps is easier for people in the second category. If you can simultaneously listen and react to what others are playing and doing whilst still concentrating on your own playing then it's perhaps easier than having to focus on one activity at a time. It's an interesting idea that I've often pondered about.

I play with one person who I don't think can do it - I don't think it is because he is a poor player just that he finds it hard to listen to what others are doing because it competely throws his own playing. It makes it hard to have much freedom when playing with him - which is ok as long as one is aware of it.

I play with other people though who spark off each other and ideas lead elsewhere because they listen and react and constantly pick up ideas, riffs, rhythms etc from each other - for me that's more fun and why I like playing in sessions as well.

Just different stuff.