Re: Ergonomics and neurology for interface designers

[David Kastrup <dak@gnu.org>]

"Eric S. Raymond" <esr@thyrsus.com> writes:

> What humans cannot do is take sensory input, process, and then *react*
> faster than spinal-reflex-arc time!  Raskin's basic discovery was that
> if you throw a mockup of your application start controls on the
> display, you have a minimum of 0.17 seconds to finish initializing the
> real controls before a human is capable of noticing and then trying to
> do something.

Well, but working with an editor in many ways is similar to typing on a
typewriter: you don't usually wait for an action initiated by a keypress
to complete before typing the next.

There are various timers in Emacs, like the one showing incomplete
command sequences or the one popping up mouse-over help, which
consciously act with a delay in the expectation that a human will
generally _not_ wait for a response by the computer before performing
his next action.

We actually had just recently a font-lock problem when scrolling with
autorepeat rates of about 30 characters per second.  You won't stop on
the dime with such rates, but one still has a chance to catch what one
is looking for.  Things like multi-file incremental search may even run
governed by the autorepeat rate.

So I don't see that we have an absolute time threshold below which
version control caused delays are irrelevant.

-- 
David Kastrup