Path: utzoo!attcan!uunet!mcvax!cernvax!pan!aratar!chac
From: chac@aratar.UUCP (Chuck Clanton)
Newsgroups: comp.cog-eng
Subject: subliminal feedback
Keywords: feedback windowing interfaces
Message-ID: <318@aratar.UUCP>
Date: 15 Nov 88 18:10:02 GMT
Lines: 62

i would like to know what other people think about an issue that
don norman provoked me into thinking about...

the question has to do with the nature of feedback.  any good tool
provides feedback as you use it, for example you feel the hammer's
position in your hand as you are pounding nails.  this feedback is
different in kind, i believe, from the information a tool may be
designed to provide.  for example, i should be able to read a measurement
off of a ruler easily and quickly.  that is what it is designed for.
i may know very little about what makes a good hammer.  for example, i
know that the balance should be right, but i have no idea what "right"
means except by feel.  clearly its balance is not information that the
hammer is intended to provide information about, rather it is intended 
to have balance as a property of its usage. 

so, we can categorize the information derived from a tool into two
categories.  the first, what i tend to call feedback, serves the specific
purpose of making the tool easier to use, more comforting, less tiring,
and less error prone.  it is more a property than an intention.  the 
second, what i tend to call the display data though this term is 
misleadingly descriptive (suggestions?), is unrelated to the first and 
has to do with providing the information the tool is designed to provide
its user.  this property may be very complex.  for example, larry tesler
has pointed out that the tracking properties for a mouse during selections
on the screen should include hysteresis during tracking, and careful
disregard of the final mouse movement during a button up.  chris crawford
provided very realistic ballistics in his atari game of Tank, and believes
that complexity was important.  these cases illustrate that complex
feedback properties can simplify and enliven the use of some tool.  unlike
a complex display of data, well-designed but complex feedback may reduce
the apparent complexity of the interface.

here is the issue that brought this up.  i have been using workstations
with multiple windows for years.  the first one i used, a long time ago,
provided feedback about my current window (the window receiving my typing)
that was sufficiently subtle that i was rarely conscious of it, but 
sufficiently apparent that i almost never made any mistakes.  so, my
awareness of my current window was subliminal.  i was not even aware of
the fact that i needed to pay attention to this.  of course, the first 
few times i used this system, i noticed (and learned) the cues.  after
that it was second nature, as the feedback from a good tool should usually
be, i think.  my current windowing system has inadequate feedback.  i
often start typing when i think i am in one window, and i am actually
in another (keyboard focus errors).  it does provide feedback...if i look 
at the cursor or the window border, i see the information displayed.  but
it is not easily obtained, and i miss the cues often.  

here is what i conclude.  in general, when designing an object to display 
data, i expect that the user wants the information and will acquire it
intentionally.  it should be displayed so that it is easy to obtain when
the user makes the effort to acquire it.  however, when designing an object
for the user to work with, its feedback properties should by and large
be very quiet.  that is, i would like the user to always know what he or
she needs to know while using this object, without ever making any effort
to acquire that information.  the needed information should be provided as
feedback that requires no added effort to obtain, no intent.  

Chuck Clanton
Seilergasse 8
CH-4500 Solothurn
Switzerland
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