We want users of a system to be able to have a lot of freedom, while keeping it simple, effective, memorable and also safe for the user. This means that when we design a system we need to keep Usability Goals in mind - these are:
- Effectiveness - We want the system to be able to do everything required of it, while having an array of features that we need. For example: If we were creating a word processer system, we would need features to allow us to change the font, colour, size, layout, background and much more. If these type of features weren't implemented into the system, then it wouldn't be effective enough to create a style or format we need and therefore; would be unusable.
- Efficiency - The system needs to complete tasks in a simple and fast manner.
- Safety - The system should not break, corrupt files or lose data etc. i.e. when inserting a DVD into the cd-tray, the system should not scratch, melt or deface the disc.
- Utility - The system allows the user to complete tasks without hassle or be required to do anything technical. Also the system needs to have a variety of functions and features that can allow the user to use shortcuts and freedom.
- Learnability - Simple display of features and functions that are self-explained i.e. they make it easy for the user to learn the system.
- Memorability - Visually allows the user to easily remember how to use the system.
Design Principles - A Short Description
These are the design priciples based on The Design of Everyday Things by Don Norman:
- Visibility - How we look at things, and how we understand something simply from the visual content i.e. you look at door with a small rectangle piece of metal engraved with the word 'push' - from this we understand straight away to move through the door we need to push instead of pull and aim for the small metal panel.
- Feedback - Showing the user a task has been completed, sending infomation back to the user about what actions have been done. Forms of feedback: Lights, sounds, animation, movement, text or a combination of any.
- Constraints - Physical, Cultural and Logical. Physical involves the movement of thing being restricted. Cultural contraints involves learned conventions which help users within technology. Logical involves the exploit of people's reasoning i.e. relationship between an object and an image can represent 'danger' or 'insert here'
- Mapping - how useful is the controls and their movements being displayed in the real world i.e. a switch to turn off a light or a number keypad to turn of the light. Which is the easier option?
- Consistency - Keeping interfaces similar as well as the elements within them.
- Affordance - How obvious is the attributes of an object to the user to allow them to know how to use it without reading instructions. i.e. A user will look at a chair and instantly know by visually looking that you sit on the chair to use it.
Scenario
A mobile phone is a common tool that is used by most of the general public, however in certain situations we need our technology to do something that enables us to use the device but not disturb our environment and surroundings. When we go to a public library we still want to be notified of a phone call or text message without being loud and disturbing people, so we may need to adjust the volume of the phone.
'John has come to his local public library to do some research. However he is expecting a text message from his girlfriend at some point during the day and a phone call from a friend. Upon entering the library John walks past a sign "No noise. Please keep mobile phones on silent or switched off." He realises he has left his phone on and needs to reduce the sound encase of a text or phone call. To do this he needs to touch the 'off' button and select Silent with Vibrate. This allows John to keep his phone quiet, but the vibration will let him know if he recieves a text/phone call on his mobile phone'
Function
Turning a phone on silent. Usually done by touching the off button once and selecting silent, or with a shorcut button on the keypad by holding it down. The best possible way would be to use the shortcut button on the bottom-right of the keypad, it has a musical symbol with a line through it to indicate to the user that it will silence sound. The shortcut button on the keypad is efficent, memorable, effective and allows the user to utilise the function within seconds. The picture that dipicts the silent feature is also usually embossed (similar to a remote control or elevator button) which allows the user to complete this task without actually looking at the mobile phone. Embossing buttons seems to have become cutural in todays society, as it is already learned there isn't the need for learnability with this function.
Design
Feedback: The feedback given to the user is usually a small, short vibration of the phone and some sort of text/picture combination i.e. with a sony mobile phone it will vibrate while displaying a musical symbol crossed out and titled "Silent Mode".
Visibility: It doesn't actually need to be viewed to perfom this function, however the keypad is embossed and a symbol is used to depict the function of the button.
Mapping: It is a very clear and concise button displayed to the user to allow them to perform the silent mode function using the shortcut keypad button.
Constraints: This function comes with the physical restraint of movement (technically) and visual movement, because if the user isn't confident/comfortable with the mobile phone, they will need to look at keypad to perform the function.
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