Addendum

I should add that Presidential thinking with two twitter fingers (of the previous post) is not that far off the mark. I often find that all kinds of useful stuff pops up from the unconscious when one is typing away, say at an essay on gender relations in the earlier  works of Jane Austen. All kinds of useful stuff which didn't pop up when tying just to think about same, unaided.

Perhaps the keyboard activity blocks most conscious activity, stops conscious processing getting in the way of the real thing, the unconscious processing. Perhaps the same sort of effect that some other people achieve by tapping their fingers or listening to light music while they do their homework.

Note, however, that I do my twitter fingers' thinking in private. That way I get a chance to read it over and separate the wheat from the chaff, the sheep from the goats. Or whatever.