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From: dykimber@phoenix.Princeton.EDU (Daniel Yaron Kimberg)
Newsgroups: comp.windows.misc,comp.sys.next,comp.sys.mac,comp.cog-eng
Subject: Re: consistency and human learnability (was desktop metaphor)(long)
Keywords: consistency, desktop metaphor, interfaces, computing environments
Message-ID: <6122@phoenix.Princeton.EDU>
Date: 5 Feb 89 05:51:41 GMT
References: <548@cvaxa.sussex.ac.uk>
Reply-To: dykimber@phoenix.Princeton.EDU (Daniel Yaron Kimberg)
Organization: Princeton University, NJ
Lines: 65

[I've lost the attribution line, but >> prefaces the remarks of Donald Norman]
In article <548@cvaxa.sussex.ac.uk> aarons@cvaxa.sussex.ac.uk (Aaron Sloman) writes:
>>I suspect that metaphors are useful in keeping consistency.  But
>>now Jonathan Grudin is about to present a paper in CHI 89 arguing about
>>the foolishness of consistency: systems are often improved by
>>violations.

>	"Power is more important than consistency"

    I wonder if it might not also be worthwhile developing the idea that
consistency is important, but misunderstood.  Of course, I'm speaking from
relative ignorance since I haven't read Grudin's paper.  But take, for
instance, a set of options displayed to the user.  Does consistency require
that all the buttons look the same, or different?  [ugly example, but you
get the idea]  Should the user interface be internally consistent? or
should it be consistent in its relationship to the system as a whole?
Not having seen Grudin's
work, I tend towards the idea that the interface should be made
consistent with the functioning of the system (different looking menus for
different sorts of options, perhaps), and only then made internally consistent
towards the goal of simplicity.  Two similar looking buttons for different
functions is a form of interface-function inconsistency.  I suspect that
interface-interface consistency (same look/feel for all buttons) is only
appropriate in situations where it doesn't reduce the salience of the
important relation between the interface and the system itself, but instead
serves to reduce the number of potentially confusing inconsistencies which
are equally salient but are not indicative in any useful (e.g. non-redundant)
way of state differences.  This is somewhat echoed in the literature in the
concern that visual representations of internal state variables be availalble
on-screen.
    I wonder if someone who's familiar with Grudin's work could mention
whether or not there's any indication as to which of these sorts of
consistency are covered, or if he makes this sort of distinction explicitly.

>(The best way to explain how 'Can you pass the salt?' is interpreted as
>a request rather than a question, is probably by saying that people
>simply remember that that is how it is used. Of course, it is possible
>to derive the interpretation using very general principles and...

It would be a good thing to note at this point that "remember" as you've
used it above probably doesn't represent memory in the traditional sense,
but rather (and more in the spirit of Dr. Norman's work) in the sense of
instantiating a certain schema.  We would have no more trouble deriving
the same interpretation from "might you pass the salt?" or "do you think
you could get me a glass of water?"

>If, for the reasons indicated, scruffy and powerful systems are
>generally easier for people to learn and use (on a regular basis) than
>neat consistent systems that obtain their power from generative rules,
>then people designing learning environments (and increasingly ALL
>computing systems will be learning environments for their users), will
>be under strong pressure to sacrifice the requirement of consistency.
>
>Dare I say QED?

I hope not.  As Dr. Norman wrote:

>>  Where consistency and mepaphor and consistent
>> system images-mental models help and where they hinder is not yet
>> properly understood.

And then he said something like "Time for more research" [i lost the line].
Not a bad idea.

                                                 -Dan