[accessibleimage] Re: An antidote to CSUN

Hi Will,

It was very interesting to read your letter. I really enjoyed it. And if I understand correctly it seems also to strengthen the argument that tactile graphics are important. That it is important to have non-linear information and for the blind this is done through tactile graphics - staggered information. Or how would you call tactile graphics? Non-serialized information?

And does this also say something about the importance of reading Braille in page form?

Regards,
Lisa


why learning Braille is important



accessibleimage@xxxxxxxxxxxxx wrote:
Hi,
Now that all the hype of CSUN is behind us, I thought it time to begin to
explore the more serious questions, the sort that are rarely touched on at
CSUN. The first question I felt worthy of an attempt at an answer is,
whether using a screen reader can ever be as efficient as using sight? There's been plenty of speculation on the topic, usually resulting in the
answer that if <insert application vendor or platform vendor> waived their
magic wand using a screen reader would be as efficient as sight. However,
after spending several years considering this, and other human computer
interaction issues related to screen reader use, I take a different view. My justification, whilst not exhaustive, is below.
The first area where screen readers appear to fall short is in their
ability to communicate semantics. Communication is all about
communicating thoughts, concepts, states, etc., and communication between
an interface for a piece of software and a user is no different in this
respect. The main problem is that screen readers, through their use of
speech and Braille, both of which are serialised forms of communication,
use less physical variables to encode semantic content than sight does. There's roughly six variables that can be used to encode semantic content,
and these are:
* The position of something on the X, Y and Z axes
* The position of something in time
* The frequency of the physical wave, represented by things like color,
pitch, etc.
* The amplitude of the physical wave, or how strong it is
Using a computer with sight typically takes advantage of five of these
variables, whilst screen readers typically only use two. So, it will take
longer to communicate the same semantic content using a screen reader than
it will sight. To some extent this has supporting evidence from
psychological studies in which the listening and reading speeds of the
same person were compared. These studies found that the same individual
could read something faster than they could listen to it. There are
differences between individuals, which can account for why some screen
reader users can listen to things faster than some people can read things,
but within the same individual the evidence seems to indicate that
listening to things is slower.
This serialisation of semantic content, brought about by the smaller
capacity of speech, also has implications for memory utilisation and
cognitive workload. Studies involving Functional Magnetic Resonance
Imaging of the cortex have shown greater activity in the cortical regions
of the brain when listening to speech than when reading something. Not
only is there activity on the left side of the cortex, in regions such as
Brocha's Area and Wernicke's Area, which is present for both reading and
listening, but listening to speech also produces activity in the right
side of the cortex, which is thought to be related to contextual priming. In addition to the extra neurological activity associated with language
processing, there is also a higher demand on short term working memory. As speech is temporary, one moment it is there, the next it is not,
someone listening to speech has to remember more than someone reading
something. It is not so easy to move back to a previously listened to
word or sentence than it is to move back to a previously read word or
sentence. Navigating by listening often involves listening to words,
deciding whether they are the ones that are saught after, and if not,
navigating some more and repeating the process.
Another consideration are the distinctions between programatic focus, the
mechanism used to shift attention with a screen reader, and visual
attention. Screen readers utilise a mechanism of programatic focus to
shift the user's attention between user interface elements. This means
that a user's attention is only focused on a single point at once,
something further compounded by a screen reader's use of serialised
output. Whilst visual attention is usually focused on a single object, it
can shrink and grow, similar to a zoom lens, to encompass more or less of
an object. This ability to shift attention from a word to a paragraph and
then onto the entire document provides a number of benefits for people
reading documents. The most obvious benefit is the ability to not only
navigate by word or line, but to navigate around the document based on
more granular objects, such as paragraphs, tables, images, etc. Whilst
similar functionality is available in some screen readers for a limited
set of scenarios, this functionality is not as flexible as the visual
mechanism used to shift attention. The visual mechanism can group
granular objects together, such as a table proceeded by a diagram, and can
jump to those with very little requirement for processing. In addition to
granular navigation, attention can also be shifted based on physical
features, such as color or location, which requires just the elements with
those physical features to be searched, as suggested by Treisman's Feature
Integration Theory. As far as I am aware, no equivalent functionality to
this exists in a screen reader. One key difference between programatic
and visual attention is that programatic attention can only be moved to
fixed points, whilst visual attention can be moved to any point or
object. The final difference worth mentioning is that attention is not
just limited to a single point in the visual field. Whilst there are
overt, indogenous, mechanisms to control visual attention through moving
the point of fixation, attention can also be focused in the periphery of
the visual field, through covert, indogenous, mechanisms. This is a
useful point, as it means that sighted people can detect changes in the
state of something that occur away from their current point of fixation
without the cognitive work involved in moving the point of fixation
So, I, for one, am beginning to form the opinion that screen readers are
not physically capable of delivering the same levels of efficiency as
sight can. This isn't to say that blind people cannot gain the same level
of efficiency, just that it looks likely that they are unable to do this
using a screen reader. What is more, is that this is not the fault of a
particular application or platform vendor, as is often claimed, but more a
problem with the core concept of a screen reader, a concept that requires
everything to be serialised.
Will



------------------------------------------------------------------------

Hi,
Now that all the hype of CSUN is behind us, I thought it time to begin to explore the more serious questions, the sort that are rarely touched on at CSUN. The first question I felt worthy of an attempt at an answer is, whether using a screen reader can ever be as efficient as using sight? There's been plenty of speculation on the topic, usually resulting in the answer that if <insert application vendor or platform vendor> waived their magic wand using a screen reader would be as efficient as sight. However, after spending several years considering this, and other human computer interaction issues related to screen reader use, I take a different view. My justification, whilst not exhaustive, is below.
The first area where screen readers appear to fall short is in their ability to communicate semantics. Communication is all about communicating thoughts, concepts, states, etc., and communication between an interface for a piece of software and a user is no different in this respect. The main problem is that screen readers, through their use of speech and Braille, both of which are serialised forms of communication, use less physical variables to encode semantic content than sight does. There's roughly six variables that can be used to encode semantic content, and these are:
* The position of something on the X, Y and Z axes
* The position of something in time
* The frequency of the physical wave, represented by things like color, pitch, etc.
* The amplitude of the physical wave, or how strong it is
Using a computer with sight typically takes advantage of five of these variables, whilst screen readers typically only use two. So, it will take longer to communicate the same semantic content using a screen reader than it will sight. To some extent this has supporting evidence from psychological studies in which the listening and reading speeds of the same person were compared. These studies found that the same individual could read something faster than they could listen to it. There are differences between individuals, which can account for why some screen reader users can listen to things faster than some people can read things, but within the same individual the evidence seems to indicate that listening to things is slower.
This serialisation of semantic content, brought about by the smaller capacity of speech, also has implications for memory utilisation and cognitive workload. Studies involving Functional Magnetic Resonance Imaging of the cortex have shown greater activity in the cortical regions of the brain when listening to speech than when reading something. Not only is there activity on the left side of the cortex, in regions such as Brocha's Area and Wernicke's Area, which is present for both reading and listening, but listening to speech also produces activity in the right side of the cortex, which is thought to be related to contextual priming. In addition to the extra neurological activity associated with language processing, there is also a higher demand on short term working memory. As speech is temporary, one moment it is there, the next it is not, someone listening to speech has to remember more than someone reading something. It is not so easy to move back to a previously listened to word or sentence than it is to move back to a previously read word or sentence. Navigating by listening often involves listening to words, deciding whether they are the ones that are saught after, and if not, navigating some more and repeating the process.
Another consideration are the distinctions between programatic focus, the mechanism used to shift attention with a screen reader, and visual attention. Screen readers utilise a mechanism of programatic focus to shift the user's attention between user interface elements. This means that a user's attention is only focused on a single point at once, something further compounded by a screen reader's use of serialised output. Whilst visual attention is usually focused on a single object, it can shrink and grow, similar to a zoom lens, to encompass more or less of an object. This ability to shift attention from a word to a paragraph and then onto the entire document provides a number of benefits for people reading documents. The most obvious benefit is the ability to not only navigate by word or line, but to navigate around the document based on more granular objects, such as paragraphs, tables, images, etc. Whilst similar functionality is available in some screen readers for a limited set of scenarios, this functionality is not as flexible as the visual mechanism used to shift attention. The visual mechanism can group granular objects together, such as a table proceeded by a diagram, and can jump to those with very little requirement for processing. In addition to granular navigation, attention can also be shifted based on physical features, such as color or location, which requires just the elements with those physical features to be searched, as suggested by Treisman's Feature Integration Theory. As far as I am aware, no equivalent functionality to this exists in a screen reader. One key difference between programatic and visual attention is that programatic attention can only be moved to fixed points, whilst visual attention can be moved to any point or object. The final difference worth mentioning is that attention is not just limited to a single point in the visual field. Whilst there are overt, indogenous, mechanisms to control visual attention through moving the point of fixation, attention can also be focused in the periphery of the visual field, through covert, indogenous, mechanisms. This is a useful point, as it means that sighted people can detect changes in the state of something that occur away from their current point of fixation without the cognitive work involved in moving the point of fixation
So, I, for one, am beginning to form the opinion that screen readers are not physically capable of delivering the same levels of efficiency as sight can. This isn't to say that blind people cannot gain the same level of efficiency, just that it looks likely that they are unable to do this using a screen reader. What is more, is that this is not the fault of a particular application or platform vendor, as is often claimed, but more a problem with the core concept of a screen reader, a concept that requires everything to be serialised.
Will


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