This means they would be doing all these things at the same time:
1. Listening to what you're saying
2. Giving some thought to what you are saying
3. Giving some thought as to what they are writing
4. Composing sentences and typing them
Which is clearly a load of nonsense. No one can do this all at the same time.
This means that either they're not thinking about what they're writing (which means the email they're sending is largely pointless), or, they're not really hearing what you're saying (they're just scanning it to check you're not saying anything interesting). In truth they're probably doing both and not really engaging with anything that's going on at all.
If people do this in your work, you should stop, and politely say, "Sorry, I find it too distracting to talk if you're typing."
photo by ahdustin
It's important to single task, because it's important to give our full attention to things. Also, if we give everything only our partial attention, we end up in a state of Continuous Partial Attention.
This is a well described psychological state where we are unable to concentrate on anything because we are waiting for the next interruption to react to.
the state is characterised by:
- feeling on alert, stressed
- restlessly looking out (e.g. refreshing your email/rss/facebook almost compulsively)
- being unable to concentrate on a single task (huge increase in procrastination)
- being unable to think deeply or creatively (can't get in the zone)
In one sense it's a microcosm of our the way we lead our lives - always looking out for the next shiny thing, rather than giving our full attention to what have (and thus not getting the most out of our current relationship for example).