Human Computer Interaction for the Visually Impaired
In exploring the field of human computer interaction the solutions that arise in the realm of accessibility tend to have the most creative solutions. In developing technologies and coming up with new innovations, people with disabilities have become more included and given more access to information. A majority of the information presented to us on a daily basis is received with the use of our eyes. Webpages, books, images, and videos are some of the most common mediums of information sharing. With that fact it is important to realize the need to come up with alternative methods of sharing this information with individuals who are visually impaired. Throughout history efforts have been made to help people with these impairments and strides are still being made to this day to further make information accessible, many of which rely on computational technology.
Overview of the Human Visual System
The human visual system handles one of the most complex cognitive processes within our brains. Input is first received through the eyes where light triggers photoreceptor cells. The two kinds of photoreceptor cells contained within the eye are rods and cones. Rods are specialized to help process visual information in low light settings. Cones on the other hand work primarily in instances where more light is present and are responsible for color vision. These cells not only collect and transfer information, they also begin processing the information received. These activated cells then relay the information through the optic nerve to lateral geniculate nucleus contained within the hypothalamus of the brain. This information is then passed along to the primary visual cortex where then it is further passed along to other areas of the brain. Processing this visual information in the different areas of the brain happens in a parallel manner and each area is responsible for a certain step. The ventral pathway is in charge of identifying objects. The dorsal pathway is responsible for identifying an objects location in space. The majority of this processing however occurs within the occipital lobe, located near the back of the skull. Finally these separate threads running in the brain come together in a combination step resulting in the experience of visual perception.
Damages to any part of this system can result in misperceiving objects and even the loss of perception. Blindness is one of the most well known disabilities regarding vision. It results in the partial to complete loss of perception. There currently exist a multitude of technologies addressing issues allowing for the digital world to be available to the visually impaired.(1)
A Brief History of Inventions for those with Visual Disabilities
Spectacles
The first major innovation designed purely for those with visual impairments is one many of us use to this day. Glasses. Originally called “spectacles”, the Italian inventor Salvino D’Armate created the first pair sometime in the late 13th century. They use specially made lenses to help the wearer bring objects into focus. Different lenses are required for varying levels of impairment and for different conditions (i.e short sightedness vs farsightedness). (2)
Braille Code
Invented by Louis Braille in 1829, this code maps a configuration of 6 raised or unraised dots to letters. This allows for people with visual impairments to feel the text and therefore understand what is written without the need to see. In developing this system of communication, Braille had been inspired by a soldier’s method of communicating at night through a 12 dot system. Braille’s code simplified that idea and produced the code that is still widely used to this day.(2)
Contact Lenses
Surprisingly the first contact lenses where invented in the year 1887 by the German physiologist Adolf Eugen Fick. These were intended to be used in a similar fashion as the aforementioned spectacles however the lens was to be placed directly onto the eye. It is worth noting that these early contact lenses were made of glass and not of silicone hydrogel like we have today. Needless to say there has been great improvements in the performance, safety and comfort in this invention since the time it’s idea was first conceived.(2)
White Canes
White canes were originally brought about by James Biggs in 1921 in order to help the blind and visually impaired navigate themselves and avoid obstacles. They also have the added benefit of letting people know of their condition and allow them to accommodate them accordingly. These canes aren’t used as frequently today and have been largely substituted by guide dogs and sighted guides. They have also been improved to use Ultrasound technology to give users better information of obstacles in their path.(2)(3)
Current Technologies for Blind and Visually Impaired Individuals
Screen Readers
Screen readers are some of the most commonly used digital technologies for those who are blind. They work by using a text to speech engine which reads out loud any textual data and menus that are presented on the screen at the time. The screen reader also repeats all of the keystrokes made by the user giving constant feedback to what was inputted in case an error was made. Another way screen readers are useful is when used in conjunction with a braille display. In this way users can physically feel the text on the screen as they go scroll through the page. There will be more information of braille displays in later sections of this article. Screen reader software can be purchased online and prices can range between free to $1200. (4) A lot of devices come with their own screen readers installed however some don’t have as many features as one’s available for purchase. They are available on both desktop and mobile devices as well. Figures 2 and 3 depict the most widely used screen readers for each of these respective platforms based on a recent survey (5).
Screen Reader Use Strategies
People who use screen readers typically have a few different strategies they employ while using the assistive system. One such strategy includes increasing the speech rate setting to be around 500 words a minute allowing for efficient ways of absorbing the information on the screen. Another strategy individuals who use screen readers employ is setting personal preferences allowing them to find necessary information on the page. They often do this by mapping keys to certain functions. For example a user could press the “H” key and receive a quick overview of all of the headings in return or “B” and have all of the available buttons to be pressed read to them. These keyboard shortcuts are critical since users typically only use the key board to interact with the information on the screen.
Designing for screen readers
These short cuts depend on the way the web page is designed, therefore developers must use best practice methods in terms of organizing all of the different sections on a page so that users that rely on screen reading functions can navigate effectively. In a study where blind or visually impaired participants were asked to give their thoughts on what can be done to make using computer’s more accessible, all of the participants included adding features and workarounds that gave them autonomy and empowered them. The study found that subjects would rather spend more time navigating a page instead of relying on the help of others to accomplish tasks. The participants also mentioned a multitude of accessibility issues that are regularly encountered. These included images without alternative text, buttons that are images, CAPTCHA without audio alternatives, information presented either in images or tables, inaccessible closed captioning, video control buttons, and auto-play videos. (6). These issues should be kept in mind by the developers as they work on the platform as well as the content creators. Another important design principle that should be followed is the way forms are written. Visually impaired users rely on the initial parts of the form to ask for the same information in the same order (i.e asking for the first and last name first, and address/contact information second). Additionally each field within the form should include labels and descriptions as to how information should be entered. If forms are designed in a way that strays from the norm it could prove to be more difficult for visually impaired users.
Braille Displays
Refreshable Braille displays are electronic devices which can translate text on screen into braille output. The Braille display contains mechanical pins that display the line the user is currently on and update the pins as the user scrolls or moves to the next line. They can either be directly plugged into the computer or be connected wirelessly. Often times these devices are used in conjunction with screen readers, however they have a few added benefits. For one these devices are quiet can be used in low noise environments. They also allow users to get a more precise representation as to what is being presented on the screen since they allow the user to identify spelling, spacing and punctuation marks. The price of these readers range from between $3,500 to $15,000 dollars depending on the amount of the characters they are capable of displaying. This number can range anywhere from 40–80 characters, however it is said that 40 characters is enough to accomplish most tasks. A refreshable Braille display with a capacity of 80 characters is likely needed for more specialized tasks such as programming. (4)
Tongue Interfaces
These devices are on the more exotic end of the human computer interaction spectrum. Tongue interface devices help blind and low vision individuals to see with the help of their tongues. The BrainPort Vision Pro is an example of such a device. This system works by taking in input through the camera located in the center of the glasses. This data is then processed by the headset and translated onto an array of 394 electrodes in the shape of the image being captured. This electrode array is placed on the user’s tongue and after training and practice the user is said to be able to interpret the shape, size, motion and location of the object. Electrical signals are outputted in way that convey these aspects onto the array and is then sensed by the tongue. It is said that it feels like sparkling water or vibrations in the area being stimulated. The benefit of this system is that it is a noninvasive way of providing some sort of visual stimulus to it’s users in a novel way. (7)
Bionic Eyes
Another example of a computational device that allows visually impaired and blind users to see is the bionic eye. This device is unique from the others in that it must be surgically implanted into the patient’s eye. During this procedure the bionic eye’s electrical components are discretely placed within the patients eye with the electrode array is carefully being placed on the retina. Once the system is in place, the user may put on a set of glasses with a camera attached. This camera takes in image input and sends it to the attached visual processing unit. Here the image is translated in a way that can be sent wirelessly to the electrode array. In doing so the electrode array sends electrical signals to the optic nerve for the brain to then interpret using the rest of it’s infrastructure. User’s have claimed to be able to notice flashes of light, read large print and navigate across a street on their own. It is limited in the sense that in order to replicate real vision the device would need 1 million electrodes in contact with the retina as opposed to the 60 it currently has. Out of all of the devices listed in this article this is by far the most expensive. It is estimated to cost $150,000 along with medical bills following the procedure. (8)
Navigation Systems
The last assistive technology that we will be going over in this article are navigation systems for the visually impaired. These primarily work through the use of mobile devices as they are capable of using GPS data and are computationally powerful enough to meet the user’s needs. They work by using audio to highlight points of interest and calls out distances as the user advances along. They can also work with local networks to transmit information on services such as transit times, descriptions and schedules. They are fairly accurate in terms of their positioning capabilities with some claiming to be accurate to 1m. They are however limited to outdoor use as that data is fairly static and known, whereas information about indoor areas is quite unpredictable. It is for this reason that user’s of this technology often use other assistive technology in conjunction in order to navigate their way indoors.(9)
Assistive technology for the visually impaired has made the visual world more easily navigable and written information available to those that need it. It is important to continue to further developing these products as our computational ability increases so that we may continue to be inclusive to these individuals. It is also important to continue to keep in mind these users when designing and creating software so that currently available devices may be used to access necessary information and to avoid making gathering information more difficult than it may already be.
References
1.“Visual Perception.” Cognition: Exploring the Science of the Mind, by Daniel Reisberg, 7th ed., W.W. Norton & Company, 2019, pp. 63–105.
2. “History: Technology for visual impairments. (n.d.). Retrieved from http://atwiki.assistivetech.net/index.php/History:_Technology_for_visual_impairments”
3. Winter, B. (n.d.). 10 fascinating facts about the white cane. Retrieved from https://www.perkins.org/stories/10-fascinating-facts-about-the-white-cane
4. Refreshable Braille Displays. (n.d.). Retrieved from https://www.afb.org/node/16207/refreshable-braille-displays
5. Screen Reader User Survey #7 Results. (n.d.). Retrieved from https://webaim.org/projects/screenreadersurvey7/
6. Tomlinson, S. M. (2016, December 27). Perceptions of accessibility and usability by blind or visually impaired persons: A pilot study. Retrieved from https://asistdl.onlinelibrary.wiley.com/doi/full/10.1002/pra2.2016.14505301120
7. BrainPort Vision Pro: United States: BrainPort Technologies. (n.d.). Retrieved from https://www.wicab.com/brainport-vision-pro
8. Hellem, A. (n.d.). Bionic Eyes: Hope for the Blind. Retrieved from https://www.allaboutvision.com/conditions/bionic-eyes.htm
9. Real, S., & Araujo, A. (2019). Navigation Systems for the Blind and Visually Impaired: Past Work, Challenges, and Open Problems. Sensors (Basel, Switzerland), 19(15), 3404. https://doi.org/10.3390/s19153404
