Re: 48px vs 44px target sizing

I've tracked down the Reference 16 in the document.
http://link.springer.com/article/10.1007/s10209-013-0320-5

Reference 17 is here:
http://link.springer.com/chapter/10.1007%2F978-3-540-73279-2_104

It should be noted that for the study I summarized previously, the users
had the device on a table that they were sitting at, and so they were in
close proximity and they were using a tablet Samsung.




this might be helpful.

Cheers,
David MacDonald



*Can**Adapt* *Solutions Inc.*
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On Mon, Sep 5, 2016 at 10:36 AM, David MacDonald <david100@sympatico.ca>
wrote:

> I agree we have to look carefully... we want to have a WCAG 2.1 that makes
> sense to all, otherwise WCAG 2.1 will end up like the sequels to the
> "Matrix"... flat and not accepted by our stakeholders.
>
> I've read through the reference sent by John looking for things that might
> help us... there are also several useful references that we may want to
> look up. There are 4 pages missing from the 16 page report in the Google
> book version but I think I can pull the major parts of it. Here are some
> quotes and a summary of key findings pertinent to our work.
>
> "When creating the prototype, we referred to research on appropriate
> button size [ 14, 15], button spacing [ 15, 16], and touchscreen gestures
> and button position [11, 17]. In our mobile voting user interface design,
> buttons arc located near the edges of the screen and the active region of
> each button is at least 20 mm in length and width (although the visual size
> may appear smaller), with at least 6.35 mm of spacing between active
> regions. Where buttons arc touching, the minimum button size was increased
> to provide additional spacing. All functionality is accessed via tap, which
> is the preferred and most effective gesture for individuals with motor
> skill impairments [ 11 ]"
>
> "although the amount of spacing included between these buttons and the
> placement of the buttons along the edges of the screen was based on
> previous research, we observed that his spacing proved insufficient,
> especially for w participants who tended to experience drifting. This
> proximity of repeated-press buttons led to accidental presses of the Next
> Contest button ... "
>
>
> ​Here's a summary of other points.
>
>    - Buttons in study were were 20mm = 75px with spacing of   6.35mm = 24
>    px  (conversion here https://css-tricks.com/the-lengths-of-css/ ) This
>    was based on research listed below.
>    - Users did better with mobile device on slanted table​
>    - Resting hand alongside of the device for support helps some users
>    - buttons on edge were better because user could support arm
>    - left and right hand versions of software are helpful for this reason
>    - 4 out of 16 participants did not have success when they touched the
>    Samsung Galaxy Tab4, probably because of excessive dwell times were
>    recognized as double press rather than single.
>    - some users used their thumbs and fingers other than the index finger
>    - Button placement personalization would be helpful.
>    - People with dexterity problems required twice the time. (literally)
>    - Accuracy of control group wass 88.8% vs 65.3% for users with
>    dexterity problems. 4 users w/ disabilities failed the task with less than
>    70%.
>    - much of their findings is consistent with previous literature.
>
>
> References #11, 14, 15, 16​, 17 are as follows:
>
> 11, and 14 are on pages left out of the Google book.
>
> 15. Touch screen user interfaces for older adults: button size and spacing
> (Jin, Z.X, Plocher, T. Kiff, L., HCI 2007 LNCS Vol 4554. pp. 933-941,
> Springer, Heidelberg 2007
> 16.  Effect of touch screen button size and spacing on touch
> characteristics of users with and without disabilities. Human Factors
> Ergonomics Soc. 54(3), 425-436 (2012), Sesto, M.E. Irwin, C.B., CHen, K.B,
> Chourasia, A. O, Weigmann. DA
>
> 17.  Mobile touchscreen user interfaces: Bridging the gap between
> motor-impaired and able bodied users. Univ. Access Inf. Soc. 13, 303-313
> (2014)
>
>
> Here's the research paper John referred to summarized here.
>
> https://books.google.com/books?id=9hOfDAAAQBAJ&pg=PA159&lpg=
> PA159&dq=Touchscreen+voting+interface+design+for+persons+
> with+disabilities:+Insights+from+usability+evaluation+of+m
> obile+voting+prototype&source=bl&ots=2a0DJQeVh6&sig=vnbIDBLP
> 6OQcTO-EJIp9L30eM2c&hl=en&sa=X&ved=0ahUKEwjruJqjudvOAhVDtRQ
> KHb-bCGoQ6AEIMjAE#v=onepage&q=Touchscreen%20voting%20interfa
> ce%20design%20for%20persons%20with%20disabilities%3A%
> 20Insights%20from%20usability%20evaluation%20of%20mobile%20v
> oting%20prototype&f=false
>
>
>
>
>
>
>
>
>
> Cheers,
> David MacDonald
>
>
>
> *Can**Adapt* *Solutions Inc.*
> Tel:  613.235.4902
>
> LinkedIn
> <http://www.linkedin.com/in/davidmacdonald100>
>
> twitter.com/davidmacd
>
> GitHub <https://github.com/DavidMacDonald>
>
> www.Can-Adapt.com <http://www.can-adapt.com/>
>
>
>
> *  Adapting the web to all users*
> *            Including those with disabilities*
>
> If you are not the intended recipient, please review our privacy policy
> <http://www.davidmacd.com/disclaimer.html>
>
> On Mon, Sep 5, 2016 at 9:00 AM, Alastair Campbell <acampbell@nomensa.com>
> wrote:
>
>> David wrote:
>> > “We've seen studies recommending up to 57px... We went back and forth
>> on 50 px but dropped it to 48px for the very reason you mention regarding
>> Android devs...  Are you recommending further reduction?
>> > It would make sense for an accessibility standard to take the upper
>> limit not the lower....”
>>
>> Ideally there would be a well-researched, known minimum size that easily
>> translates into CSS pixels, and the platform standards would all use that.
>>
>> However, we aren’t there so I think it would help to have a common
>> ‘story’, either:
>>
>> - It uses the lower end of the platform standards and we can say “use
>> platform standards”.
>>
>> OR
>>
>> - It uses something larger than any of the platform standards, so we can
>> say “The platform standards aren’t enough, please make targets bigger”.
>>
>> Choosing the upper end of the platform standards is messy, it means that
>> some developers don’t have to worry, others do.
>>
>> So there are three options compared to the platform standards: 1) lower
>> end; 2) upper end; 3) above.
>>
>> In the case of 2 or 3, there needs to be a good rational for why the
>> platform standard (i.e. iOS) is not large enough.
>>
>> Sorry that I have probably missed that reasoning, but this is the type of
>> push-back that Alan was talking about so I’m just trying to preempt it!
>>
>> Cheers,
>>
>> -Alastair
>>
>>
>>
>