Designing for Accessibility

Julian G Jones

Slide 1
Designing for Accessibility

Acceptable (The purpose of the system must be acceptable)
Usable (The system must be well designed and easy to use for all users)
Accessible (Accessibility must be designed in from the start. It is expensive to add accessibility features later in the design process.)

Slide 2
Are biometric systems different?

Subjects must be present to register their biometric information
Biometric features are fixed but change slowly. (We cannot change our faces or fingerprints on a daily basis but they change as we age.)
Surgery or injury may change a biometric feature and require re-registration
Subject groups vary - age, ethnicity (Some older women's fingerprints are difficult to capture.)
May not require any conscious action (It is unclear what a subject needs to do and how they should behave if the process fails.)
No absolutes (Two different biometric samples from the same person will not be a perfect match.
It is a question of setting a percentage of probability. The designer has to consider several factors including the level of security when setting the appropriate percentage of probability.)

Slide 3
Biometric technology

Biometric samples vary
Balance of probabilities
Environment is a factor (Lighting, temperature and humidity can affect the quality of samples.)
Data is encrypted in most systems
Cannot be read by a human technician (The biometric data is parameterised and encrypted so it is difficult to determine the reason for a failure to match samples.)
Reference samples may be held on a chip or in a database (In the case of a sample on a chip the match will be one to one. Identification of an individual from a database is likely to be more complex and may introduce delays before the system responds.)
Identification or verification

Slide 4
Acceptable Systems

Slide 5
Usable Systems

Attended or unattended (Good design, high availability and help information is vital for unattended systems.)
Simple consistent interface features
Clear typeface
Logical flow of actions
Clear prompt for the next action
Errors, warnings and help
Reset, Cancel or escape (It is essential to be able to reset the system if the user knows they have not presented the biometric sample correctly, for example: the user has presented the wrong finger.)
Standard icons and symbols (must be clear and it is wise to use standard symbols where they are available.)
Use of branding (Biometric interfaces will be unfamiliar to most users. Branding should not be so dominant that it obscures the essential features of the interface.)

Slide 6
Environment and physical features

The equipment site must be accessible
Signs must be clear
The position of the subject (This may be critical for success and must be achievable by people with disabilities.)
- Facing the equipment
- Correct distance
- Height
- Posture

Slide 7
Environment and physical features

Impact on different biometric technologies and the subject
- Lighting
- Markings on the floor (Footprints indicating a standing position are of little help to a wheelchair user or people with visual disability.)
- Angle and position of a fingerprint reader
Multimodal biometric systems
- May require the user to move position (One position may be necessary for face recognition and a second to give a fingerprint.)

Slide 8
Designing Accessible Systems

Consider the potential users
Unwelcome surprises (Users must be informed of changes to the interface or new feature.)
Store user's preferences
Offer alternatives
- Languages
- Font size
- Colour combinations
- Speech and audible feedback
Speed of interaction (Some users take longer to respond to prompts.)
Feedback on progress (Give clear indication that an event has occurred or an attempt has failed and what happens next.)

Slide 9
Designing Accessible Systems

Consistent position for features
- Must be within reach
- Finger print reader
- Card slots and keypads
Retain standard features (If they are required these features will be familiar and build confidence.)
- Keypads
- Function keys
- Standard tactile symbols
Smart Cards
- Contactless card (Can avoid some problems for users who have dexterity problems. They also allow a user's preferences to be detected before any other interaction has taken place.)

Slide 10
Explaining the System

Slide 11
Support for biometric subjects

Attended Systems
- Well trained attendants
- Understanding of disabilities
Unattended Systems
- Access to help
- Alternative processes and procedures
Resolution of false recognition or rejection (There must be a contact available to resolve these conditions. This is particularly important for unattended systems that may be used at unsocial hours.)

Slide 12
Registration of subjects

Registration takes time
Security requirements
- supporting documents
How many registration sites
- accessible transport
- accessible building
Attended registration (Registration should always be attended to explain the process)
Cost of registration and re-registration
- who pays?
What happens to users who are unable to register? (Users should not be excluded from essential systems and services.)

Slide 13
Summary

Experience is limited (Very few systems have been deployed for use by large numbers of the general population.)
We are all learning
Share experience (It is important to be in contact with other's working on biometric systems and standards.)