Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!sdd.hp.com!think.com!snorkelwacker.mit.edu!stanford.edu!unix!ctnews!pyramid!athertn!hemlock!mcgregor
From: mcgregor@hemlock.Atherton.COM (Scott McGregor)
Newsgroups: comp.human-factors
Subject: re: adaptive interfaces
Message-ID: <35537@athertn.Atherton.COM>
Date: 20 Jun 91 18:13:54 GMT
References: <91Jun19.155043edt.6300@neat.cs.toronto.edu>
Sender: news@athertn.Atherton.COM
Reply-To: mcgregor@hemlock.Atherton.COM (Scott McGregor)
Organization: Atherton Technology -- Sunnyvale, CA
Lines: 96

In article <91Jun19.155043edt.6300@neat.cs.toronto.edu>,
mgreen@cs.toronto.edu (Marc Green) writes:

> The major problem is that the system's response is not completely
> predictable. People like machines to be slaves and to know that the
> same thing will have everytime. 

My experience with developing adaptive interfaces is that the above
statement is an oversimplification of a more subtle point. As a result,
it throws out
the baby with the bathwater.  My empirical observations do not suggest
that people want slavish predictability, rather they want the ability to
form useful habits.  Normally this implies a certain amount of
predictability, and
repeatability, but it is not necessarily a slavish form.  For instance,
consider a scrolling list of items.  An alphabetical layout may be more
predictable, but a layout based upon putting the last used items at the
top may be more convenient--and in cases where the same object is worked
on for a long time, this allows the formation of a habit (grab item at
top of the list) that might not be developed with the alphabetic list. 
Now in the case
of the alphabetic list, you don't have to know any previous state to
know where to look--so it is more predictable, but less useful if
presumption of former
state can be taken for granted.  There are many other common examples of
this sort of adaption based upon past state: E.g. the Macintosh root
window remembers your previously open folders, IBM SPF remembers
previous used field entries, etc.  The more slavishly unchanging typical
unix login sequence:
"login:, password:, cd $HOME, shell prompt" is actually frequently more
disatisfying to many users than the remembered Macintosh style boot-up,
and this has lead to various different desktop approaches (X.desktop,
LookingGlass, HP VUE) which are now trying to provide this level of
adapatability as well.  

Now this is only a very limited level of adaptability (often so limited
that many people neglect it), but even it is sufficient to demonstrate
how slavish application of such generalizations concerning predictability
can interfere with usability improvements.  This extends to many other
more complex adaptive situations, such as the EAGER hypercard macro generator
discussed in the most recent CHI proceedings, or the Prescient Agent X
windows system described in the May '90 HP Professional.

Thus, a better way to state the general truth that Marc was trying to
convey is: "if an adaptive interface interferes with habit formation,
then it will annoy people, and reduce usability."

> Moreover, an adaptive interface is going to make a lot of mistakes.
> Any diagnostic system, including ones which have to diagnose user 
> intentions, makes errors.

This is obviously true.  However, it does not necessarily follow that
the cost of the error will matter to the user.  For instance, consider
an adaptive interface used in an application to allow the user to choose 
a different a file to work on.  The first time the application is used,
the pull down menu for new file selection just allows the user to type
in a new file name.  After that, the user can still have the ability to
select files by typing in the name, but can also choose from recently
used files automatically added to the list.  An additional filename
added to the menu that the user
doesn't care about is in one sense an error, but it doesn't interfere
with the users actions so it is not annoying (additional examples of
this sort of
error are discussed in the Prescient Agents paper.

> And Imagine the poor user when he tries to do  something new for the
first   > time and the interface keeps classifying as it some previously
learned
> intention.

If it gets in the way, then it is a bad interface, adaptive or not.  But
that doesn't mean that all adaptive interfaces interfere in this way, and so
not all adaptive interfaces are bad.  They aren't all necessarily good
either. This is not an area to go about designing by mechanically
applying generalizations -- there is still considerable individual
talent components to designing good interfaces.

> I'd put my money on customizable systems or systems which give advice
> on how to use more advanced features to accomplish a task more easily.
> This still puts the user in control, and that's where he wants to be.

Advice and user directed customization aren't the only ways to leave the
user in control. Sometimes the user's reactions to advice or the possibility of
customization is frustration that the computer doesn't just do it.  (Or
at least offer to do it!).  Many thoughtful adaptive interfaces do leave
the user in control.  My paradigm for an adaptive interface in our
prescient agent work was M*A*S*H's company clerk Radar O'Reilley whose
ability to "precache" answers to unasked questions facilitated his
colonel's productivity instead of interfering with it. Adaptive
interfaces can also be more like a "let me do it 2 year old" too, but
they don't have to be, and shouldn't be judged solely on the worst case
situation alone.

Scott McGregor
Atherton Technology
mcgregor@atherton.com