On 5/24/2023 2:12 AM, Martin Brown wrote:
> On 23/05/2023 23:26, Don Y wrote:
>> On 5/22/2023 3:36 PM, Joe Gwinn wrote:
>>> On Mon, 22 May 2023 22:03:05 +0100, Martin Brown
>>> <'''newspam'''@nonad.co.uk> wrote:
>>>
>>>> On 22/05/2023 17:31, Don Y wrote:
>>>>> I recall seeing references regarding *certain* aspects of
>>>>> human body characteristics -- height, weight, hand size,
>>>>> etc. -- that were used in industrial design of equipment
>>>>> and interfaces.
>>>>>
>>>>> But, it seems to me, that the number of such *potential*
>>>>> metrics is really only limited by the imagination (e.g.,
>>>>> how much weight can a person support on an outstretched
>>>>> arm; how much pressure can a person apply with a finger
>>>>> tip; etc.)
>>>>>
>>>>> [i.e., "abilities" instead of "characteristics"]
>>>>>
>>>>> So, it seems likely that there isn't One Grand Reference
>>>>> for all this stuff.
>>>>
>>>> The military have some pretty good ones for male and female if you can
>>>> find them, but I have no idea about their classification status.
>>>
>>> The US Military does have a publicly available handbook on this, and
>>> the UK will have a like (or identical?) handbook. It's called human
>>> factors or the like (don't recall the precise name), and it contains
>>> much measured data summarized in probability distributions. A typical
>>> requirement is to design from the male 95th percentile to the female
>>> 5th percentile.
>>>
>>> Found it:
>>>
>>> "MIL-STD-1472F, DEPARTMENT OF DEFENSE DESIGN CRITERIA STANDARD: HUMAN
>>> ENGINEERING (23 AUG 1999)., This standard establishes general human
>>> engineering criteria for design and development of military systems,
>>> equipment, and facilities. Its purpose is to present human engineering
>>> design criteria, principles, and practices to be applied in the design
>>> of systems, equipment, and facilities. "
>>
>> There are other related documents that similarly address practices, etc.
>>
>> But, the information available in these (and lots of other, similar) documents
>> are too general. And, you can't make inferences about metrics that haven't
>> previously been tabulated. You can infer how a diode will work in
>> a completely new application based on data characterizing its performance.
>> People aren't as easily "summarized" (even *a* person)
>
> OTOH enough of the main characteristics are similar enough that you can avoid
> making gross mistakes by following the MIL spec guidelines.
Depending on the population you're addressing and the way you are
extrapolating the data...
>> How much force can a person be expected to *comfortably* exert to
>> actuate a control? (imagine folks with arthritic hands/fingers)
>
> That is another can of worms. Many child proof caps on pill bottles are also
> impossible for people with arthritic fingers to open (as are some of the anti
> tamper seals on eg bottled water for normal fit adults).
Yet the size and force constraints would be deemed "appropriate"
for the populations identified in those documents. Because the
documents don't reflect how those populations "age".
[I've a friend who proudly told me he was working out with
ONE POUND weights! I laughed thinking it a reference to
"twelve ounce curls" (the weight of a can of beer weighing)
only to discover that he really meant one pound weights!
I guess strength falls off rapidly as the population ages
(for folks who haven't taken steps to preserve it!)]
[[Is there a metric that explains why old folks can't
look over their shoulder while driving??]]
>> How much force should be required to ensure a control isn't
>> accidentally actuated? (imagine parkinsonian/essential tremor)
>
> There are guidelines on haptic devices and their feedback. I found some active
> haptic feedback on my hire car most disconcerting.
>
>> How "fine" the motor skills to invoke a mechanism? (imagine a young child
>> invoking an "emergency alert" or position a pointing device)
>
> It depends on the age of the child - look at toys designed for different ages
> if you want to get an idea of what works and what doesn't.
"It depends" is entirely my point. How did the designers of those
items come to realize the constraints appropriate for them? Not
by consulting a book/standard but, rather, by empirical observation.
Effectively conducting their own surveys of "user capabilities".
>> Calculator vs. phone keypad? QWERTY/AZERTY/Dvorak/etc.? (and
>> characteristics vary depending on how reified -- try typing on
>> a membrane keypad vs. discrete switch vs. touchpad vs. ...)
>>
>> [This last being a mix of anthropometric and cultural issues]
>
> I grew up with QWERTY and can touch type on it have lived in countries with
> AZERTY keyboards and always had to look for some rarely used letters but could
> still by the end of it type on them pretty well. It didn't help that I still
> used QWERTY at home.
But you still had expectations for what to find approximately-where.
I went to make an adhesive label with a caret ('^') in the text,
yesterday. Only to discover that the character can not be created
by the labelmaker! And, on close examination of the positions
of the non-alphabetic glyphs, realized that they were "all wrong".
E.g. SHIFT-6 was "'", tilde was missing -- as was '+'/'=', and
both angle-brackets, SHIFT-_ was '"', SHIFT-, was '?' while
SHIFT-. was '/', etc.
Another device had the digits assigned to the top row of keys with
a special "shift" action. Other keys had punctuation characters
similarly assigned.
[ObTrivia: What ten-letter word can be typed on the top row of keys?]
A third had the keys arranged alphabetically (when is this EVER right?)
Granted, one doesn't expect to type "at speed" on such devices.
But, I spent a fair bit of time examining all the keys AND all
of the "modes" in an attempt to locate '^' -- to no avail!
The sheer number of keys on the keypad and their arrangement would
never have led me to imagine that it wouldn't BE there!
>> You need to *gather* the data (vs. looking up published *metrics*)
>> to address specific needs. Or, make hopeful guesses...
>>
>> How often have you seen informal and /ad hoc/ "meetings" where folks
>> poke at a prototype and come to a decision based on their limited
>> data points? I guess it's not worthy of an "engineered" solution!?
>
> The usual one is that dead flesh keyboards may be wonderfully wipe clean and
> neat but they are horrible to use for significant data entry.
But, one would assume the fingertip size distribution would allow
one to design appropriately sized keys! I can type reliably on
a phone's mechanical (or touch) keypad despite the keys being
a fraction of a fingertip-size. Yet, on a membrane keypad,
would need something considerably LARGER than a fingertip-size
to even hope to get the keystrokes correct! And, the stiffer the
material, the truer the statement! (e.g., the keys on our
microwave oven are exactly the same size as the keycaps on this
keyboard -- but, have a relatively light actuating force so
using it doesn't leave you feeling ham-fisted.
OTOH, I've designed maritime products where the keys were twice
the width and height in order to be reliably operated (because
they had such high actuating forces suited to their operators!)
The hidden problem with such technologies is the user has no
way of determining if the interface is "broken" or just
"unresponsive" to HIS actions. "Gee, the STOP button doesn't
seem to be working (perhaps because it has been overused?).
Let's see if RUN works... Yup, that did it! Shit, now how
do I *STOP* it???"
But, in no case can I recall anything other than an informal
"what-do-YOU-think" approach to making those decisions. Never
any "engineering".
> IOW OK for the occasional interaction but nothing more.
>