'No way,' he says to himself as he reads something that was obviously quite interesting, '... not golf on Saturday.'

Without so much as a glance in my direction, he begins to type out what seems to be quite a lengthy reply. Just as I'm contemplating getting up and going for a walk, he hits 'send' and puts his PDA down. He puts it right in front of him on the bar, a clear signal to me of where his priorities lie, and says: 'Sorry Alan, what were you saying?'

This has been happening quite a lot lately. I had a building contractor come over to my place yesterday to repair something electrical.

In the middle of my explanation of what is required, he receives a text message.

'Hold on', he says while drafting a response. And just like with Dave, I have no choice but to stand there like an idiot waiting for him to finish.

And this problem cuts across all ages and social groups. It is very common to see groups of teenagers sitting in Starbucks or McDonald's, all sending text messages and not talking to each other. And when Barack Obama was giving his very first speech to a joint session of the US Congress last month - an historic occasion no matter what your politics are - several congressmen who were lucky enough to be in the room were posting fairly trivial text messages on Twitter.

To ignore a real live person right in front of you while attending to an electronic message seems to have become normal behaviour. I'm not innocent in this whole scenario, I'm part of the problem too. During meetings I regularly find myself checking if there is anything more interesting on my Blackberry than what is going on around me.

How on Earth did this happen? I mean it is obviously rude if in the middle of a conversation I start reading a book. Even if it's a really good book. So isn't it at least as rude to write, or reply to, some inane text message in the same circumstances?

The answer is that it is rude, and everyone knows it. But even though everyone really does know that it is obnoxious to read e-mails in the middle of a conversation, we are all becoming incapable of resisting. And this is a modern problem that will only get worse.

If I'm at home watching a business channel on television, there will be at least one person on the screen talking, and at the same time I can see instant stock prices, currency prices, bonds, commodities and so on. Plus, the headlines of various news stories will be scrolling across the screen. Even then, I will almost definitely also be writing e-mails on my Blackberry or surfing the internet on my laptop as I watch TV. Or both.

So how am I supposed to go from that to simply sitting and listening to someone talk? It's just not realistic.

The real problem is not that people are too rude to ignore their PDAs or mobile phones while having a conversation.

The real problem is that the technology does not yet exist to enable us to do both at once.

It is still necessary to take our attention away from the person we are speaking to in order to write an e-mail. There is no picture-in-picture and no heads-up display in real life. Not yet, anyway.

Technology will soon rescue us from this uncomfortable transitional phase. Researchers at the University of Washington are working on a contact lens that can effectively recreate a computer screen right on the wearer's eyeball.

Looking through it, you would be able to see the world as you do now, but superimposed on that will be a computer display with your e-mails, a web browser, Grand Theft Auto, or whatever.

When this thing gets working I will be able to sit in a meeting and appear completely focused on whoever is speaking, while at the same time watching the latest episode of America's Next Top Model and checking my Twitter account.