Re: Letter and Word Spacing: Final Analysis

Hi All,
Steve asked for my support materials. Here they are.

Wayne

On Tue, Jun 13, 2017 at 3:26 PM, Wayne Dick <wayneedick@gmail.com> wrote:

> This is the Chung article.
>
> On Tue, Jun 13, 2017 at 3:03 PM, Wayne Dick <wayneedick@gmail.com> wrote:
>
>> OOPs
>>
>> On Tue, Jun 13, 2017 at 3:02 PM, Wayne Dick <wayneedick@gmail.com> wrote:
>>
>>> Here is the McLeish. I send you Chung as soon as I download them.
>>>
>>> Wayne
>>>
>>> On Tue, Jun 13, 2017 at 1:56 PM, Repsher, Stephen J <
>>> stephen.j.repsher@boeing.com> wrote:
>>>
>>>> Wayne,
>>>>
>>>>
>>>>
>>>> Can you email me those PDFs?  I don’t have a subscription to access
>>>> them for review.
>>>>
>>>>
>>>>
>>>> Steve
>>>>
>>>>
>>>>
>>>> *From:* Wayne Dick [mailto:wayneedick@gmail.com]
>>>> *Sent:* Tuesday, June 13, 2017 3:33 PM
>>>> *To:* public-low-vision-a11y-tf <public-low-vision-a11y-tf@w3.org>
>>>> *Subject:* Letter and Word Spacing: Final Analysis
>>>>
>>>>
>>>> Letter and Word Spacing Summary of Results:
>>>>
>>>> For best reading results the spacing should be .25em maximum. However,
>>>> the loss of performance between .12em and .25em is less than 1/4 in reading
>>>> speed. I think .15em is the best because that gives 95% of the benefit.
>>>> After that there is almost no benefit. After .25em there is none.
>>>>
>>>> Word spacing may not be necessary, because browsers tack on the letter
>>>> spacing to the normal word spacing anyway.
>>>> Good News / Bad News
>>>>
>>>> The good news. Alastair and I are both right in our calculations.
>>>>
>>>> The bad news. Alastair and I are both right in our calculations.
>>>>
>>>> We have a serious political decision to make.
>>>> Analysis
>>>>
>>>> My letter spacing was based on an article, “A study of the effect of
>>>> letter spacing on the reading speed of young readers with low vision”, Eve
>>>> McLeish, Visual Impairment Service, UK (British Journal of Visual
>>>> Impairment 25(2) 2007). In this article, the author builds a table for
>>>> spacing of typed assignments for children with low vision. The formula she
>>>> used was STEP=[fontSize/20], for each test bracket. Each STEP represents
>>>> increasing the letter spacing by 1/10 of the letter size. She used points
>>>> for her font size but we will use pixels.  McLeish found significant
>>>> results with reading speed up to n*STEP for n=1… 5. However, the slope went
>>>> from steep to horizontal in this range. It was concave down going flat at
>>>> n=5. When I computed these results, I started at n=5. Example: for font
>>>> size of 16px, 5*STEP = 5(16px/20)=4px=0.25em. The formula works the same
>>>> for all font sizes.
>>>>
>>>>
>>>>
>>>> I got to these values the first time and noticed that the performance
>>>> curve really flattened between n=3 and 5. It grew from 0 to 20% increase in
>>>> reading speed from n=0… 3. Then grew from 20% to 22% between 3 and 5. I
>>>> should have selected 3 first and got 3*.8=2.4px= .15em.  Fear of developer
>>>> response, got the best of me, so I suggested the .12em. At that size, the
>>>> performance curve still gave a 15% increase in reading speed.
>>>>
>>>> For testing, I used Firefox with, Tahoma and the text, “Lorem ipsum
>>>> dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor
>>>> incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis
>>>> nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo
>>>> consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse
>>>> cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat
>>>> non proident, sunt in culpa qui officia deserunt mollit anim id est
>>>> laborum.” I got the following results:
>>>>
>>>> Let Average Char be the number of pixels taken by an average character
>>>> in the passage.
>>>>
>>>> Letter Spacing
>>>>
>>>> Average Char
>>>>
>>>> Increase
>>>>
>>>> Normal
>>>>
>>>> 7.004px
>>>>
>>>> 0
>>>>
>>>> 0.12em
>>>>
>>>> 8.921px
>>>>
>>>> 1.917px or 27%
>>>>
>>>> 0.15em
>>>>
>>>> 9.404px
>>>>
>>>> 2.4px or 34%
>>>>
>>>> 0.25em
>>>>
>>>> 11.004px
>>>>
>>>> 4.0px or 57%
>>>> Controversy
>>>>
>>>> Aside from the huge impact on layout there are other difficulties.
>>>>
>>>> The research is mixed. The benefits of letter spacing are measured by
>>>> various experiments in the range from no effect to simply miraculous.
>>>> McLeish is in the middle; her methodology is sound, and she observes the
>>>> impact in the most natural setting. Her findings rang true with my
>>>> experience.
>>>>
>>>> The most significant article that shows no effect is: The effect of
>>>> letter spacing on reading speed in central and peripheral vision by S. T.
>>>> Chung (Investigative Ophthalmology and Visual Science, 2002 Apr,
>>>> 43(4):1270-6). Chung’s methodology is sound, but she uses a different
>>>> instrument for measurement. McLeish uses flash cards while, Chung uses
>>>> Rapid Serial Visual Presentation (RSVP). The words are drifted past at
>>>> varying speeds. Chung’s theory is that an individual can read faster when
>>>> more letters are fit in the most sensitive reading zone of a reader’s
>>>> retina. Increased letter spacing reduces this value and therefore reading
>>>> speed must suffer.
>>>>
>>>> Both authors are correct, in my opinion.  This needs to be tested of
>>>> course, but here is my reasoning. McLeish’s use of cards, forces the
>>>> participant to orient their most sensitive reading zone each time the card
>>>> is presented. Thus, McLeish measures orientation and recognition. Chung
>>>> uses text that drifts into the participants optimal reading zone, so no
>>>> orientation is needed. This would mean that the benefit in letter spacing
>>>> would be in helping the reader orient their most sensitive reading zone to
>>>> the target.  That is just a theory, but it does explain the difference in
>>>> two well designed studies.
>>>>
>>>
>>>
>>
>