Demands for screen magnifier user qualifications

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Morten Tollefsen, Cathy Kalvenes, Bjørn Gulbrandsen, Miriam Nes Begnum

Target group:

Screen magnifier



1. Background


The recent Norwegian Discrimination and Accessibility Act will place much greater demands on Universal design of Web technology. Web sites should be accessible and usable for everyone, also all groups of disabled users.


The Web Content Accessibility guidelines (WCAG 2.0) to some extent ensure usability. However usability obviously requires that disabled users have specific knowledge. What is "perceivable" and "operable", according to the WCAG guidelines, will be determined by the level of knowledge / experience the user has. A definable and measurable level of user competence is therefore important for testing and developing accessible and usable Web sites, and will be meaningful in all Research and Development projects focusing on Web technology.


The main goal of this project is to define demands for user qualifications to utilize WCAG 2.0 Web sites and to use the definition to develop a framework to teach and test required user skills. The two user groups in focus are: blind and severely visually impaired users, and users with cognitive disabilities.


This document is the final version of user demands for persons using a screen magnifier.




2. Theoretical and practical knowledge


In principle sighted and visually impaired persons should have comparable theoretical and identical practical knowledge. Techniques may vary, but visually impaired and sighted users should be able to perform the same tasks given an accessible website. When trying to define demands for user competence, it is therefore advantageous to use a standardized certification scheme.


The International Computer Driving License (ICDL) is built on 7 modules. One of these modules (number 7) is "Web browsing and communication". The skills outlined in module 7 should enable a user to manage the web efficiently. Module 7 also includes email which is not a part of this user demand specification.


The skills and theoretical knowledge specified in ICDL module 7 are used as a basis for demands for qualifications for visually impaired persons. In addition, to be able to work quickly and efficiently on a website, a screen magnifier user needs to master techniques and functionality specific to the screen magnifier. This knowledge is described below.




3. Screen magnifier specific knowledge

A screen magnifier user sees only a small part of the page on the screen, and will not therefore get an immediate overview of the whole page.  The reduction in overview is proportionate to the level of magnification the user requires. Also web page design, for example heading size / text size, and text / background color, influences perception of page content, especially at higher magnification levels.  

Specific screen magnifier functions are used to get an overview of the page, thus enabling the user to locate desired information. The techniques an individual user chooses to employ will vary, depending on the structure of the page, and the level of magnification. It is essential, especially with higher magnification, to have a good knowledge of specific screen magnifier functions, and their shortcut keys, to be able to use the Web effectively.  


3.1 Using shortcut keys

Page navigation is more effective when shortcut keys are used.

Keystrokes should be used to:

  • Scroll left, right, up and down
  • Move to the beginning / end of the page
  • Move to the previous page
  • Use the internal search function
  • Use the mouse to focus function


3.2 Zoom in/out

The zoom in function is used to increase magnification to a sufficient level to allow the user to read text content. Zoom out does the opposite, reducing magnification to get an overview of page content. This functionality is particularly relevant for users requiring lower magnification levels. The magnification level may also vary during the day, for example increased fatigue may necessitate higher magnification towards the end of a working day.  The user should be able to use shortcut keys to:

  • Increase/decrease the zoom level
  • Turn on/off the zoom function


3.3 Panning

Panning allows much smoother page movement than moving around the page using the mouse. At higher magnification levels a user will typically start at the top left corner of the page and pan left and right, and up and down, so moving across and down the page. The user should be able to use the shortcut keys to:

  • Pan screen left, right, up and down
  • Move the zoom window to the top, bottom, left and right side of the page
  • Increase/decrease panning speed
  • Stop panning


3.4 Color schemes and mouse enhancement

It is useful to be able to set up a customized color scheme which changes the color presentation of the page and allows many users to reduce magnification considerably for many web pages. The color scheme can be switched off if it is not suitable for the color contrast used on a particular page, and when looking at photos/graphics.

Most screen magnifiers allow the user to customize the appearance of the mouse pointer, and to use mouse locators to guide the user to the mouse pointer. The pointer enhancement can be switched off if covers text, making it difficult to read.

The user should be able to:

  • Toggle the color scheme on/off
  • Toggle the pointer enhancement on/off


3.5 Links

On a web page which is not familiar, the user may move through the links by pressing Tab for the next link, or Shift+Tab for the previous link as these commands cycle through all links. This is very time consuming on a large page. The user should therefore also be able to select links using the links list functionality found in most screen magnifiers. This function is particularly useful to locate links on the right hand side of the page which can be hard to find using the mouse or by panning.

The user should be able to:

  • Tab to next/previous link
  • Selecting links using the links list
  • Be able to make use of visited links


3.6 Synthetic speech

Many users find synthetic speech a great help, especially at high magnification levels. The user should be able to use the shortcut keys to:

  • Toggle synthetic speech on / off
  • Increase / decrease speech rate
  • Change speech engine
  • Say page title

Excepting links and form controls, most screen magnifiers must use a dedicated text reader to read text content on a web page. The user should be able to use shortcut keys to:

  • Activate the text reader
  • Start / stop the text reader
  • Move focus one word left / right
  • Move focus up / down a line
  • Move focus to the beginning / end of the line.


3.7 Move mouse to focus

When a user tabs or pans through a page the mouse pointer often disappears from the zoom-window. In this case the move mouse to focus function is useful so the user does not have to move the mouse manually.

  • The user should be able to use the mouse to focus


3.8 Internal page search

The internal page search function is a quick and easy method to locate text on a web page, reducing the need for screen movement by panning / mouse and lessening fatigue.   The user should:

  • Be able to use internal search


3.9 Use different strategies to locate information

A screen magnifier user has the possibility of using different strategies to locate information on a web page. The user should be able to use different approaches, depending on the structure of the web site and the task to be solved. These strategies include:

  • Panning around the page
  • Tabbing around the page
  • Using the links list
  • Using the internal search function
  • Using color schemes

The best navigation strategy will vary depending on the level of magnification required. The user should be capable of selecting and changing strategy.