HCI - Accommodating human diversity

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As graphical and general processing capabilities improve, the growing need for research into human computer interfaces becomes more evident. Designers are expected to provide a transparent interface to the core of their software that can facilitate work for all levels of users. When designing a user interface many aspects of human diversity must be taken into account. Depending on the purpose of the software, designer must take into account factors such as but not limited to:

  • Age
  • Race
  • Physical Attributes/Disabilities
  • Mental Disabilities
  • Educational Background
  • Computer Expertise
  • Geographical Location
  • Cultural Background


Universal Design

In general, universal design is a cross discipline approach to design that helps create products that are usable and effective for everyone. The design principles for Universal Design are as follows.R1

  • Equitable use
Use of the object or software must be as "fair" as possible. This means that regardless of user type, they can all perform the same actions and receive the same benefits form the product. This however seems to be a fairly lofty goal with regards to complicated software. Instead this can be interpreted in the sense that regardless of the type of users, given a reasonable amount of time, they will gain the same benefits from the product. Software and it's interface should provide all the necessary tools to aid beginners in reaching an adequate level competency within a reasonable amount of time.
  • Flexibility in use
The design should be able to accommodate a wide range of users based on factors such as preference and ability. For example, expert users should not be held up by an interface designed for beginners, likewise, a beginner should not be expected to use expert style interactions.
  • Simple and intuitive
Use of the product is easy to understand, regardless of the user's experience level or background. Keep the interface simple by reducing unnecessary complexity, and be consistent with user's expectations. Offering prompt informative feedback will eliminate frustration as well as reduce learning times.
  • Perceptible Information
Necessary information should be effectively communicated to the user regardless of any disabilities the user may have. Any feedback given to the user should have adequate contrast against the surrounding information. In general elements should be distinguishably different to clearly convey the message of difference or importance to the user.
  • Tolerance for Error
When designing an interface, or functionality of software, designers should always strive to minimize faults or error that may be caused through inadvertent actions by the user. There are many techniques to help with this issue. Grouping objects based on functionality or confirmation of action are useful tools. It would be unwise to say, place the "load" and "delete" buttons side by side.
  • Low Physical Effort
Although this principle is stated for real world objects, it carries over quite well. Users should not have to dig through multiple menus or perform an excessive amount of actions to obtain a given functionality. The number of actions required to perform a task should be fairly proportional to how often that action is used. Very common functionality should be readily available to the user at all times, or be made readily accessible with ease.
  • Size and space for approach and use
Once again, although this principle is stated for the real world, it applies very well to HCI. A simple interface is an efficient interface. Important elements should be easily visible regardless of the user's physical abilities. Positioning of the elements should also be intuitive. Grouping of elements and clear separation of the interface based on functionality can help with this.

8 Golden Rules

The 8 Golden Rules proposed by Ben Shneiderman also provide a very good basis when thinking about interaction design.R2

  1. Strive for consistency
  2. Consistent sequences of actions should be required in similar situations; identical terminology should be used in prompts, menus, and help screens; and consistent commands should be employed throughout.
  3. Enable frequent users to use shortcuts
  4. As the frequency of use increases, so do the user's desires to reduce the number of interactions and to increase the pace of interaction. Abbreviations, function keys, hidden commands, and macro facilities are very helpful to an expert user.
  5. Offer informative feedback
  6. For every operator action, there should be some system feedback. For frequent and minor actions, the response can be modest, while for infrequent and major actions, the response should be more substantial.
  7. Design dialog to yield closure
  8. Sequences of actions should be organized into groups with a beginning, middle, and end. The informative feedback at the completion of a group of actions gives the operators the satisfaction of accomplishment, a sense of relief, the signal to drop contingency plans and options from their minds, and an indication that the way is clear to prepare for the next group of actions.
  9. Offer simple error handling
  10. As much as possible, design the system so the user cannot make a serious error. If an error is made, the system should be able to detect the error and offer simple, comprehensible mechanisms for handling the error.
  11. Permit easy reversal of actions
  12. This feature relieves anxiety, since the user knows that errors can be undone; it thus encourages exploration of unfamiliar options. The units of reversibility may be a single action, a data entry, or a complete group of actions.
  13. Support internal locus of control
  14. Experienced operators strongly desire the sense that they are in charge of the system and that the system responds to their actions. Design the system to make users the initiators of actions rather than the responders.
  15. Reduce short-term memory load
  16. The limitation of human information processing in short-term memory requires that displays be kept simple, multiple page displays be consolidated, window-motion frequency be reduced, and sufficient training time be allotted for codes, mnemonics, and sequences of actions.

    Although some of these principles cross over, they lend themselves to universal design with regards to software.


When creating a Human Computer Interface, it is important to take a step back and consider who is going to be using it. The physical, mental, and cultural state of the end user will vary, and knowing how this could effect how they perceive your interface is critical. Addressing these different characteristics of the possible end user, there are several categories which designers need to consider.

End User Diversity

As stated in Principle #1 of Human Factor Considerations in Human Computer Interface, it is necessary to recognize the diversity in the abilities of the user. The ability of the user can be categorized into three levels of skill types:

  • Expert
User that uses the computer and applications as part of regular job duties. This type of user likely makes frequent use of shortcut keys and command line input.
  • Occasional
User that is not a frequent user and may need prompting from time to time to accomplish computer based tasks.
  • Novice
User is new, requires as much feedback, help files, and hints as possible. Visual representation of objects and the use of natural language is important for this type of user.

By knowing who your end users may be for your interface, you may have to take into account all three users, or specifically make it for one of the three types of users.

Audio Considerations

Another factor that must be considered in the diversity of the end user is their hearing. Users will have varying ability to hear or recognize audio output from an interface.

  • Frequency
As both men and women grow older (to a greater extreme men)R3 we lose the ability to discern different frequencies of sound, especially at higher frequencies. The interface must take into account that the end user may have a smaller range of identifiable sounds, and make any audio queues within the audio range of any user.
  • Volume
It is also necessary to have any of the audio output from the interface to be loud enough for the user to understand. It may be necessary to have the volume of any audio outputs to be variable to allow any user comfortable audio output.

Visual Considerations

Age related Macular Degeneration

It is also a necessary requirement that any user is able to visually understand what is displayed on the screen. Some factors that need to be considered are:

  • Colour Contrast R4
To make any text displayed to be as legible as possible, it is necessary to have sharp contrast between background and text. The best suited background colours are achromatic colours: black, white and grey, with the textual colours fall within the middle colours of the spectrum: yellow, green and orange. Red, blue and violet are on the extremes of the human visual spectrum so our eyes are not as sensitive to them, making them difficult colours to contrast with others.
  • Colour Blindness R4
A portion of users may suffer from colour blindness and be unable to detect slight variations in colour, making certain aspects of an interface unreadable to them. This can be avoided by using a sharp contrast between background and text. As well, for this reason an interface should not rely on visual cues alone.
  • Animated Visuals
Objects on a screen that are non static, being blinking, moving, updating etc. can cause the users that are screen read challenged difficult in reading or understanding the object. These objects must have the option to be frozen or paused for the user to understand its message.
  • Resizing
For users with limited visual ability, it is necessary to allow the user to change the size of the what is being displayed. This could include changing font sizes, resizing object sizes, or any other method to make an object understandable for a user with diminished visual ability.
  • Visual Queues
Timed pop up menus or hints that are not read and understood before they hide again also need to be considered. If the end user has a problem understanding the message before it disappears for any reason, be it age or visual impairment, then the queue needs to appear for a longer duration to the user.
  • Photo sensitivity
Epilepsy is a neurological disorder characterized by recurrent convulsions. Photosensitive epilepsy is a form of epilepsy in which seizures are triggered by visual stimuli such as flashing lights or moving patterns. Epilepsy occurs in approximately 1 in every 200 people and photo epilepsy occurs in approximately 1 in every 4000 people. About 96% of people while photo epilepsy are sensitive to light flashes between 15-20 flashes per second. For this reason blinking or updating of a CRT screen should be avoided, as this can cause flickering between 4 and 59 Hz and will likely trigger a convulsion.
  • Visual Conditions
For users with limited vision due to age it is important to take into account the position and size of objects, text and visual cues. For example, macular degeneration is a condition resulting in loss of central vision. Should the software be intended for the aged, positioning the locus of control to the left or right of the screen may prove to be a benefit.

Designing for context

When designing a system for widespread use, it is important to understand the region an interface is being implemented in. When an interface is contextually valid, it reduces the chance of the system being misused due to simple misunderstandings in language and visuals.

Cultural Context

It is crucial to understand the culture and customs of the region a system is to be implemented in. Doing so can greatly reduce the amount of learning time needed by users of the system.

Some important aspects to consider:

  • Previous knowledge
It is possible that a previous method of complete the task the software is being designed for existed for some time. The design of the previously used equipment should be taken into account in order to make the transition to new software as easy as possible.
  • Symbols
Avoid use of symbols and/or colours that have some cultural significance in the area the interface is being designed for.
  • Terminology
Certain terms and phrases may have different meanings to different cultures. Instructions and commands should be made as plainly and clearly as possible.
  • Traditions
Certain cultures may have standing traditions related to either a previous edition of software, or to an area where new software is being implemented. An interface should be designed to be as consistent as possible with these traditions.
  • Imagery
Use universally understood visual metaphors, as different cultures may have different meanings for the same image. For example, a red traffic light may mean stop to one person and not to another.
  • Training Techniques
Consider the mental strategies which will be adopted by operators and the resources required in terms of background knowledge. These resources should be made clear and readily available to minimize the learning curve.

Linguistic Context

Additionally, understanding the natural language of a region is vital to the system's usability. If the users cannot understand the interface, the system will not function as they wish.

Some example considerations:

  • Multi-Language Support
If an interface is to be employed in a region with multiple dialects, the interface should support multiple languages for its display, or make use of common visual cues. Switching between supported languages should also be as intuitive as possible. For example, the option to change the current language setting to French should not be displayed only in English.
  • Grammar and Syntax
Ensuring proper grammar, spelling, punctuation etc. is vital for the interface's usability.
  • Character Variation
Some languages may share characters and/or words that are visually the same, but pronounced differently. For the sake of ease-of-use it is important to ensure all textual information is grammatically correct.
  • Idioms and Metaphors
Different languages and cultures may have phrases or words that hold a unique meaning in a specific context and not well understood by others. When designing an interface textual elements should be written in plain language (whatever that language may be) without the use of common expressions or sayings.
  • Slang
Use of slang should be avoided, similarly to idioms, as it is too easy to misunderstand without proper context.

Human Properties

  • Gender
Males and females tend to interact differently with computers; ideally, interfaces should be designed to be gender-neutral. Study in this field has uncovered gender differences relating to user confidence/behaviour and hardware interaction. R5
  • Handedness
This mainly comes into play when designing physical interfaces – control panels, for example. An interface should always be designed such that both right handed and left handed operators can make use of the system with minimal inconvenience.
  • Age
Note that the senses, particularly hearing and vision, degenerate with age (see above). A good interface takes this fact into consideration, and provides utilities to deal with decreasing physical faculties (i.e. increased volume, text size).
  • Intellect (Educational background, profession, experiences)
For certain applications (for example, control systems interface in a nuclear reactor), a certain baseline level of education can be assumed. However, in general, it is poor design methodology to assume that the end user will have the same education, training, or life experience as the designer. Interfaces should be designed in such a way that they do not require a great deal of specialized knowledge to use.
  • Emotional/Mental Characteristics
When designing for a specific demographic, aspects such as attention span, emotional state, and motivation must be taken into account. Interfaces likely to be utilized in emergency situations should be as simple and direct as possible, whereas educational software interfaces can be more complex and entertaining, as they must hold the users attention in a meaningful way.
  • Culture
When deploying an interface in an unfamiliar region, it is imperative that none of the symbols used be offensive in the local culture. As well, no element should be incomprehensible to the locals. Idioms and colloquialisms are to be avoided for this reason. An outside specialist may be required to advise on this aspect. See also Cultural Context.
  • Size/Spatial Aspects
The height, weight, and reach of the end-user must be taken into account. Interfaces should be designed to accommodate a range of physiques.
  • Visual Capability
Conditions to be considered include blindness, near/farsightedness, and colourblindness. Visual considerations are discussed above.
  • Auditory Capabilities
Deaf users should be taken into account. If the interface relies heavily on sound, accompanying visual indicators should be included.
  • Physical Disability
Accommodations for physically disabled users should be provided wherever possible. This could include anything from larger buttons to voice activation and touch-screen interfaces.
  • Mentally/Learning Disabled
When designing for special populations, the capabilities of the user must be taken into account. An interface for such a population should be as straightforward and easy to learn as possible.
  • Other Conditions
Epilepsy (covered above) is one example of a condition that does not fall under any other heading. Any other such common issues in the user population must be accounted for.

Platform Type

An interface must be designed with the actual device it will run on in mind. An interface designed to run on a standard desktop, for example, would likely be unusable on a mobile device such as a cell phone. In addition, time-sensitive systems (the interface for a plane's avionics suite, say) should provide information as directly as possible, rather than relying on complicated visuals which may slow response time.

See Also

  1. List of HCI Topics


  1. Center for Universal Design
  2. 8 Golden Rules
  3. Hearing Loss
  4. Colour Contrasts
  5. Gender HCI
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