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RE: CSS nested list menus, how much is too much?

From: John Foliot - WATS.ca <foliot@wats.ca>
Date: Fri, 12 Aug 2005 08:18:45 -0400
To: <lois@lois.co.uk>, <w3c-wai-ig@w3.org>
Message-ID: <004601c59f37$fe3808f0$6401a8c0@bosshog>

Lois Wakeman wrote:
> Rebecca,
> At the risk of teaching you to suck eggs, would you not be able to
> gauge an approximate answer to your question by attempting to
> navigate some sample menus using Lynx, for example - and see how you
> get on? 
> FWIW, I think partially-concealed dynamic menus are pretty hopeless in
> usability/IA terms, as you can so easily lose the context.  It is
> debatable as to how useful real people find complex and exhaustive
> navigation schemes - even though designers often love them as a way
> of avoiding doing the IA analysis properly ;-)
> Lois Wakeman
> -------------------------
> http://communicationarts.co.uk
> http://lois.co.uk

[As referenced in my earlier post, but re-printed here:]

While I do appreciate that certain times and instances would warrant
consideration of a flyout menu, developers *must* be reasonable in the
application of this type of technique.  Using multiply nested lists that
"compact" via CSS and/or JavaScript may visually help visual users,
however we must all understand that for some users, too many choices is
confusing at best, and may in fact cause "failure" in their quest. 

How much is too much?  Wish I had a definitive answer.  But *I do* know
when there is too much... But it's an instinctive reasoning, rather than
hard science - just like knowing what is "appropriate" ALT text.  My
acid test is this - can I remember all of the options available once
I've been exposed to them all?  How many *can* I remember?

Some studies[1] have suggested that the "Magic Number" of 7 (+/- 2) is a
reasonable number to work with - but does that mean 7 lists of seven
options?  Visually impaired users I know would argue that having an
initial 49 navigational choices would be too many - especially if they
were arriving at a site for the first time.  

In a 1997 CHI (Computer Human Interface) paper [2], it was noted, "The
basic insight is that, in order to navigate through a world with minimal
prior knowledge of its layout, .... that they [developers - JF] shall
not overwhelm the user with information. In particular for view
navigation, Furnas showed that it is ideal to show only small views (a
relatively small number of choices) that the number of navigation steps
is not too large and that the route to any target must be discoverable."
A Microsoft study [1.2] demonstrated that accuracy diminished as more
"sub-levels" (hierarchy) were added (in other words one nested list
inside the master list is preferred over a list inside of a list inside
of a list).

However, George A. Miller (the original author of "The Magical Number
Seven") noted "The point seems to be that, as we add more variables...,
we increase the total capacity [of differentiation - JF], but we
decrease the accuracy for any particular variable.."[1.1]

Now I ain't no CHI expert - but clearly these guys have research backing
up my assertion - too many initial choices hinders rather than helps.
It seems that you *can* have more than 7, but the more you add, the less
accurate the end user's results become; so at what point do we "turn the
corner"?  Sadly, there still seems to be no "definitive" answer as to
"how many?".  Like many of the choices we make, it all depends...


The other significant issues are that of mobility impairments and
alternative user agents.  Tightly packed hyperlinked objects can cause
issues for users who lack fine motor coordination, either due to some
form of disability, age (too young or too old?) or simply because the
user agent and/or input tools they are using cannot provide the required
finesse. (Some people like those trackball thingies, or touchpads - I
don't like either...)

So, if you *really* must employ flyout menus, do so with caution and
prudence - they cannot become the collapsing site map present on every
page, as this will simply defeat any positive effect you are striving
for.  As well, I would caution any developer who is *mandated* to
achieve a certain level of compliance to any of the "standards" (be it
Section 508 or A, AA, AAA) that due to the cognitive load issue you
*may* not be in compliance - blanket claims of any of the pre-packaged
(or even "roll-year-own") solutions not-withstanding:

WAG Priority 2 - 12.3 Divide large blocks of information into more
manageable groups where natural and appropriate.
WAG Priority 3 - 9.4 Create a logical tab order through links, form
controls, and objects.
WAG Priority 3 - 13.6 Group related links, identify the group (for user
agents), and, until user agents do so, provide a way to bypass the

John Foliot  foliot@wats.ca
Web Accessibility Specialist / Co-founder of WATS.ca
Web Accessibility Testing and Services
Phone: 1-613-482-7053 

[1.1] The Magical Number Seven, Plus or Minus Two: Some Limits on Our
Capacity for Processing Information
[1.2] Is the Magic Number 7 Relevant to Web Page Design
[2] Effective View-Navigation. Human Factors in Computing Systems CHI
'97 Conference Proceedings, New York, NY: ACM Press
_the_acm_chi_97_human_factors_in_computing_systems_conference.html -
requires subscription)
Received on Friday, 12 August 2005 12:19:06 UTC

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