Welcome to Module 2 on Assistive Technologies. Part 1 of this module describes the assistive technologies used by persons with visual impairments. We will review the challenges these persons face along with the limitations encountered when using assistive technology devices.
The video you previously reviewed conveyed Kyle’s story of the challenges he faces when accessing content using a computer. Kyle is an example of a student who is considered blind. His limitation is on the far end of the visual impairment spectrum. While some people who are legally blind may have some vision, they typically do not rely on their eyes to perceive visual content.
On the other end of the visual impairment spectrum is low vision, which can be caused by eye defects or diseases such as cataracts, diabetic retinopathy, glaucoma, and macular degeneration. People with low vision have varying degrees of sight. For example, persons with glaucoma may have blurred or fuzzy vision while someone with macular degeneration may not be able to see something directly in their sight but with peripheral vision.
Color blindness falls somewhere in between. Color blindness is the inability to perceive a difference between certain color combinations. The most common type is a red-green deficiency where it is difficult to perceive a difference between various shades of red and green. For example, someone with this deficiency may not be able to distinguish between dark red and dark green.
Now, let's explore some of the challenges faced by persons with visual impairments.
Persons with low vision or blindness face some challenges when using a computer. They have difficulties viewing the monitor or screen and generally do not use a mouse to navigate, particularly if they are blind.
Now’s lets see how someone with color blindness can experience difficulties with web-based content. Someone with color blindness can see but not in the same color schemes as a typical person. This image is an example of how colors are distorted by someone with a red-green color deficiency. The picture on the left is how a typical person views the red / green color combination. The red and green colors are very distinct. The picture on the right illustrates how a person with a red-green deficiency perceives these colors. You may notice that in the picture on the right the red and green colors are not easily distinguished. They appear as light and dark shades of brown. If you do not detect any differences between the two pictures, you may have a red-green color deficiency.
Therefore, the use of colors for highlighting key concepts presents challenges for persons with color blindness.
We have identified some challenges encountered by persons with visual impairments. Now, let's explore examples of assistive technologies that can help to access on-screen or computer-based content.
Several types of assistive technology devices have been developed to aid those who are visually impaired.
There are output devices designed to indicate what is displayed on the screen. These are known as screen readers. Some popular brands include JAWS (Job Access With Speech), Window Eyes, and Easy Web Browsing. These devices read the entire screen in a linear fashion. They typically do not provide the overall framework. Usually they indicate how many links are on the page.
Screen readers are quite expensive. Some screen readers allow you to download an evaluation or demo version which runs for thirty or forty minutes and then times you out, prompting you to reboot your computer.
Screen Magnifiers are devices that enlarge the screen or monitor for viewing. Zoomtext has the ability to split frame so you can see the original to gain a sense of layout and the magnified screen in another frame for navigation. With Zoomtext, the magnified screen is not as pixilated. MAGic from Freedom Scientific is also a popular magnifier, which functions like Zoomtext.
Screen readers and magnifiers only address the output function associated with computers. Specialized input devices may be needed. Since blind and low vision persons have difficulty with sight, they may use a Braille keyboard with raised keys to enter text and commands.
Voice recognition software may also be used to input data rather than typing commands or text. Dragon Naturally Speaking is a software program that allows the user to speak into a microphone to record speech. The speech is automatically converted to text. There are also other voice recognition programs that will interpret voice commands to actions on the computer.
For visual representation, displayed are images of a Braille keyboard and screen magnifier. A Braille keyboard looks similar to a standard keyboard because it has letter keys and a rectangular shape. However, as opposed to a standard keyboard, the keys are raised with Braille lettering and there are other special keys for input.
The example provided of a screen magnifier illustrates how this software program works like a magnifying glass, enlarging the screen for viewing.
While assistive technologies for the visually impaired help to convey content, there are some limitations.
Let's start by discussing some limitations encountered with screen readers. Even though they are sophisticated technologies for reading on-screen text, they can present problems. For example, screen readers cannot convey emotion or voice intonations. Technological advances have been made to mimic a natural voice, but most utilize a robotic tone, especially the demo or evaluation copy.
Screen readers also cannot describe images unless there is alternative text, or alt text. Even if alt text is included, it may not be descriptive enough to provide a mental image for someone who is blind.
Screen readers cannot provide the visual layout that one with sight would obtain by viewing the on-screen content. Because a screen reader speaks the content in a linear fashion, usually one word at a time, it cannot easily skip over unnecessary content.
Sometimes, text presented in different formats may pose a problem for screen readers. For instance, if a document is scanned, it may appear as an image file rather than readable text. Word documents and PowerPoints may also present a problem in they are not saved as an accessible PDF or HTML document. Also, the wording of text may confuse someone with or without a screen reader. For example, non-descriptive links such as “click here” do not give a person enough information about what will follow. Plus, it's difficult for someone with low or no vision to understand where to click.
Data tables can be quite confusing when read line by line. Envision interpreting a large data table with 20 columns and 40 rows. You would have to remember what the columns were as the screen reader speaks line by line, or row by row. By the time you get to the 20th row, it would be a daunting task to remember what was column 10.
Chat tools and instant messaging are very problematic. These technologies refresh the screen with each entry, which can be very frequent in this synchronous environment where information is exchanged in real-time. Because screen readers communicate the text on screen in frames each time the screen displays, the screen reader may not get through the first entry by the time the second entry is displayed. Most web-based synchronous tools use Java programming, which is not accessible. The screen refreshes automatically and cannot be controlled manually by the user. If the interface is designed with HTML (hyper-text markup language), the screen can be refreshed manually.
Screen Magnifiers enlarge the viewing area making it difficulty to see the visual layout. Not all screen magnifiers use a split screen where you can see the original image. Also, some screen magnifiers can pixilate the output, reducing the clarity for someone who is already challenged with low vision.
Keyboard accessibility also complicates matters when websites are designed with events that depend on the click or movement of a the mouse. An example would be when a user moves over a particular object which triggers an event or action that is relevant to use.
Now that you’ve learned about various assistive technologies used by persons with visual impairments and the challenges and potential limitations encountered with these devices, take a few moments to complete the Experience it! Activity in Part 1 of this module. You can experience first-hand what it is like to access content with a visual impairment.
