Guidelines
Checklist for Touchscreens
 No significant benefits  Minor benefits  Major benefits |
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| The touch screen is shielded from sunlight | |
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| The screen is angled towards the horizontal to provide arm/wrist support |
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| The screen is perpendicular to the line of sight |
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| The text and background colour combination is of high contrast | |
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| Use of blue, green and violet is kept to a minimum |
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| There is no noticeable flicker on the screen |
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| The structure of the visual display allows the user to predict where to find information and how to use it |
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| Controls |
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| Touch sensitive areas or keys are between 20 - 22mm across* | |
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| For mobile devices with touchscreens targets are 9.2 - 9.6mm across** |
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Graphical symbols are accompanied by text |
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There is a high contrast between touch areas, text and background colour |
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Text or controls are not placed over a background image or a patterned background |
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White or yellow type on a black or dark colour background is used |
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Controls are labelled in a large high contrast font |
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Audible output or tactile output is provided for identification of controls and for results of activating controls |
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An inactive space of at least 1mm is provided around each target |
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Labels are easily distinguishable from controls |
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Controls are operable by a mouthstick, headstick or other similar device |
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Commands can be entered by voice |
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The height of the active areas on the screen is between 800mm and 1200mm |
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The system provides a clear control that permits the user to go back a step |
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Controls are positioned on the screen in a way that is consistent with their functions |
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All labels and instructions are in short simple sentences |
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Text versions of audio prompts are synchronised |
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There is speech output for on-screen instructions |
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Existing colour conventions are adhered too, for e.g. red for stop |
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Guidance is distinguishable from other displayed information |
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Information is relative to the task rather than a generic message |
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Multi-modal help is offered |
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Users can switch off help prompts if they are not required |
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Audio messages are short and simple |
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Abbreviations are not used in audio messages |
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Users can interupt the help facility and return to the task |
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*According to Namahn (2000), touch sensitive areas or keys, for users with no impairments, should be of a "minimal size: 22mm across". However, Colle & Hiszem (2004) recommend that a "key size no smaller than 20mm...should be used if sufficient space is available". See Touchscreens guideline for references.
**According to Parhi, Karlson and Bederson (2006), for one-handed thumb use of mobile handheld devices equipped with a touch-sensitive screen "target size of 9.2mm for discrete tasks and targets of 9.6mm for serial tasks should be sufficiently large...without degrading performance and preference". See Touchscreens guideline for references.
Checklist for Controls
Checklist for Displays
Checklist for Keys
Last updated: 20.02.2008 © Copyright reserved
