Re: Mobile needs a question answered

Alastair
thoughts inline

On Wed, Jan 30, 2019 at 12:36 PM Alastair Campbell <acampbell@nomensa.com>
wrote:

> Sorry, I missed Jim’s email before responding to an LVTF one, this is the
> updated, full version!
>
>
>
> I’ll try sifting through some of those links, but there is a basic
> question that was raised during the 2.1 discussions:
>
> *Is it better to have medium buttons spaced apart, or large buttons
> closely spaced?*
>
>
>
> E.g. imagine 6 buttons across the bottom of a 320px wide screen.
>
>
>
> Is it better to have:
>
>    - 6 buttons at 53px wide and no margin between them, or
>    - 6 buttons at 44px wide and ~11px margin between them?
>
> The centre of each button could be the same distance apart, but which is
> easier?
>
>
>
> Do the phone OS heuristics make a difference to which is better, or
> nullify the difference? Does the heuristic enable you to miss small
> targets, but as long as there isn’t another target in the area it activates
> anyway? (That’s my experience.)
>
>
>
> The upshot could be that the guideline needs to be about spacing between
> the centre of targets, not how large they are.
>

Exactly. This is the point the Mobiles question.
How many pixels in between 2 active elements on a screen meets user need on
the low-vision side?
currently, Mobile TF have that spacing at two pixels.
hmm, rereading all of this again...
yes, spacing between center of targets is important, and seem to be the
prevailing heuristic used by OS to determine target activation.
visual separation is also an issue for differentiation of targets. the
google/android spec for mobile says 8dp between targets
of note is a study I found using older adults (65-95 in age) using Spacing
 between  targets  ... 5  levels:  0  mm,  3.5  mm,   7   mm,   and 10.5
mm,   plus   an   additional   level   for   non-­‐adjacent   targets   (a
  single   target  with  no  neighbors). "
Surprisingly "... spacing  between  targets  did  not  show  significant
 effects  in  either  of  the  tasks"  (tapping or swiping different
targets). [1]
BBC says 1px of inactive space between targets (
https://www.bbc.co.uk/guidelines/futuremedia/accessibility/mobile/design/spacing
)

So we have (changed all measurements to device pixels - dp)
MATF proposing 2dp
BBC says minimum of 1dp
android says 8dp
and a study saying spacing is not an issue.
seems the answer may be somewhere between 0-8 non-collapsible space.

perhaps we can talk more on the LVTF call tomorrow.


1.
https://webcache.googleusercontent.com/search?q=cache:m7xl4zoWoVkJ:https://hillside.net/plop/2012/papers/Group%25201%2520-%2520Elk/Target%2520and%2520Spacing%2520Sizes%2520for%2520Smartphone%2520User%2520interfaces%2520for%2520Older%2520Adults%2520-%2520Design%2520patterns%2520Based%2520on%2520an%2520Evaluation%2520with%2520Users.pdf+&cd=11&hl=en&ct=clnk&gl=us
a different paper that cited the results of the paper above - with charts
http://eprints.maynoothuniversity.ie/6621/1/PAS_user%20interface%202015.pdf
and a book "Creating Mobile Gesture-based Interaction Design Patterns for
Older Adults: a study of tap and swipe gestures with Portuguese seniors" -
https://repositorio-aberto.up.pt/bitstream/10216/64972/2/27603.pdf

Jim

>
>
> That also impacts how it aligns with low-vision issues, as you could
> differentiate buttons with spacing more easily than ones which are right
> next to each other.
>
It has been difficult to find research on visual separation of adjacent
items.

>
>
> Cheers,
>
>
>
> -Alastair
>
>
>
>
>
> *From:* Jim Allan <jimallan@tsbvi.edu>
> *Sent:* 30 January 2019 15:47
> *To:* Wayne Dick <wayneedick@gmail.com>; MATF <
> public-mobile-a11y-tf@w3.org>
> *Cc:* Alastair Campbell <acampbell@nomensa.com>; Jonathan Avila <
> jon.avila@levelaccess.com>; public-low-vision-a11y-tf <
> public-low-vision-a11y-tf@w3.org>
> *Subject:* Re: Mobile needs a question answered
>
>
>
> Alastair,
>
> As the question originally came from the Mobile group, I am looping them
> into the conversation. Perhaps they can add comments.
>
>
>
> Based on several articles - seems 8dp is a reasonable spacing.
>
>
>
> *"**Touch targets should also be spaced about 8 pixels apart, both
> horizontally and vertically, so that a user's finger pressing on one tap
> target does not inadvertently touch another tap target."*
>
>
> https://developers.google.com/web/fundamentals/accessibility/accessible-styles
>
>
>
> *"**To balance information density and usability, touch targets should be
> at least 48 x 48 dp with at least 8dp of space between them." *-
> https://material.io/design/layout/spacing-methods.html#touch-click-targets
>
>
>
>
> https://medium.com/@zacdicko/size-matters-accessibility-and-touch-targets-56e942adc0cc
>
>
>
> one caveat - the articles all point back to google/android specs. Most
> other articles related to target spacing are vague ("reasonable space", "a
> good amount of space", etc.) and are not helpful.
>
>
>
> other Related stuff I found while searching for target spacing.
>
> an old article with lots of research
>
>
> https://www.uxmatters.com/mt/archives/2013/03/common-misconceptions-about-touch.php
>
>
>
> <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5726769/>
> *Reading Digital with Low Vision - NCBI - NIH
> <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5726769/>*
>
>
>
> * <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5726769/>*
>
> *https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5726769/
> <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5726769/>*
>
>
>
> http://www.4ourth.com/Touch/
>
>
>
> On Wed, Jan 30, 2019 at 8:47 AM Wayne Dick <wayneedick@gmail.com> wrote:
>
> Hi Alastair,
>
> It kind of reduces to the same thing. It easy to miss a target you cannot
> separate from another. I'm a little embarrassed to admit how many times I
> hit the wrong target.
>
> Wayne
>
>
>
> On Wed, Jan 30, 2019 at 12:41 AM Alastair Campbell <acampbell@nomensa.com>
> wrote:
>
> Hi Jim,
>
>
>
> Was that for seeing things, or hitting the targets?
>
>
>
> Those seem like different problems, especially as the touch-screen OSs
> have heuristics so that if you tap between two targets, it guesses which
> you meant...
>
>
>
> -Alastair
>
>
>
> Apologies for typos, sent from a mobile.
>
>
> ------------------------------
>
> *From:* Jonathan Avila <jon.avila@levelaccess.com>
> *Sent:* Tuesday, January 29, 2019 11:45 pm
> *To:* Wayne Dick; Jim Allan
> *Cc:* public-low-vision-a11y-tf
> *Subject:* RE: Mobile needs a question answered
>
>
>
> HI Wayne, I also think that people with low vision might need more space
> because touch might not be as precise given that a person may be holding
> the device closer to their face and not have the same perspective as
> distance.  Also scotomas may also impact touch target accuracy for some
> users.
>
>
>
> Jonathan
>
>
>
> Jonathan Avila, CPWA
>
> Chief Accessibility Officer
>
> *Level Access*
>
> jon.avila@levelaccess.com
>
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>
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>
> *From:* Wayne Dick <wayneedick@gmail.com>
> *Sent:* Tuesday, January 29, 2019 5:24 PM
> *To:* Jim Allan <jimallan@tsbvi.edu>
> *Cc:* public-low-vision-a11y-tf <public-low-vision-a11y-tf@w3.org>
> *Subject:* Re: Mobile needs a question answered
>
>
>
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>
>
> Hi All,
>
> Well all zoomed pixels are large, but that is only so that we can see
> them. So, I would assume that it takes 2-pixels for full sighted readers to
> separate things, it would take us 2 big pixels to distinguish things.
>
>
>
> Wayne
>
>
>
> On Tue, Jan 29, 2019 at 1:47 PM Jim Allan <jimallan@tsbvi.edu> wrote:
>
> How many pixels in between 2 active elements on a screen meets user need
> on the low-vision side? Mobile TF have it at two pixels.
>
> And does the overall target size impact the spacing between elements
> requirement?
>
> Anybody have any ideas or research?
>
>
>
>
>
>
>
> --
>
> Jim Allan, Accessibility Coordinator
>
> Texas School for the Blind and Visually Impaired
> 1100 W. 45th St., Austin, Texas 78756
> voice 512.206.9315    fax: 512.206.9452 http://www.tsbvi.edu/
>
> "We shape our tools and thereafter our tools shape us." McLuhan, 1964
>
>
>
>
> --
>
> Jim Allan, Accessibility Coordinator
>
> Texas School for the Blind and Visually Impaired
> 1100 W. 45th St., Austin, Texas 78756
> voice 512.206.9315    fax: 512.206.9452 http://www.tsbvi.edu/
>
> "We shape our tools and thereafter our tools shape us." McLuhan, 1964
>


-- 
Jim Allan, Accessibility Coordinator
Texas School for the Blind and Visually Impaired
1100 W. 45th St., Austin, Texas 78756
voice 512.206.9315    fax: 512.206.9452 http://www.tsbvi.edu/
"We shape our tools and thereafter our tools shape us." McLuhan, 1964