Usability
Week 1 – introduction
https://www.let.rug.nl/meindertsma/usability/
User: peter
Pass: kleio
What is usability?
Ease of use, how to use objects
A part of interaction design: the interaction between humans and objects they use
Usability goals:
Is it effective? If you push a light switch, does the light goes on?
Is it efficient? Is it easy to push the light switch?
Is it safe to use?
Does it function right? Is there a dimmer on the light? Can a user do much with it?
Is it easy to learn to use?
Is its usage easy to remember?
User experience: larger, usability is a part of user experience
- How do people experience a specific product (enjoyment and satisfaction, attractive
name, elegant)
Wanted aspects, unwanted aspects
Usability & user experience
Differences: potential conflicts (can a product be enjoyable as well as safe)
Different goals and how to measure these (not always overlapping)
The design of everyday things
Daily challenges: do you use all functions of devices?
Slide projector: only 1 button (next slide, short click, previous slide, long click)
Telephone sets (landline phone): transfer a call? Adjust the volume?
Usability concepts
Affordances perceivability of an objects to see if you can use such a thing without
explanation (push a light button, push a door handle), visual affordances (icons that are self-
explanatory), without affordance (what are these things doing there): with affordance (this
explains the usage)
Physical & virtual affordances
If a simple objects like a door needs instructions, then it probably indicates a poor design.
- Make the method of use visible
- Use a conceptual model
, Conceptual model how we understand how things works without understanding its
precise operation (because it is not necessary), people make their own image of how
something works.
- Car/computer
- Traffic lights: how often or how long do you press the button?
- Thermostat: do you turn up your heating to get it warm quicker?
Visibility hidden functions lead to problems (when number of functions is greater than
number of buttons)
With visible functionality, the user can directly use all functions
Example: bathroom buttons (hot/cold, on/off)
Mapping relationship between the button you press and the result of that
Light switch dilemma: which button controls which lamp?
Size = value (money)
Feedback let a user know what is happening (beep, light, display, loading bar etc.), can
also be a physical change (turned knob, flames)
Constrains Limitation of the number of possible actions, prevent selection of wrong
options
Physical objects often have constrains: most keys can only be inserted in a lock in one way,
differences of cable input/output
Software constrains: inactive options in menus
Logical or ambiguous?
www.baddesigns.com
Consistency design interfaces with similar functions and elements for similar tasks (easier
to use and remember) ctrl-button.
There are often too many functions that can be connected this increases the risk of
making errors
Internal/external consistency
Internal: operations behave the same within an application
External: operations, interfaces are similar in several applications and machines
Keypad numbers layout: example of external inconsistency
Both are conventions, but they are not consistent
Conventions accepted norms of standards
Can be artificial, arbitrary, or learned
Often determined by culture
Use conventions with respect, violate them only with great risk
Week 1 – introduction
https://www.let.rug.nl/meindertsma/usability/
User: peter
Pass: kleio
What is usability?
Ease of use, how to use objects
A part of interaction design: the interaction between humans and objects they use
Usability goals:
Is it effective? If you push a light switch, does the light goes on?
Is it efficient? Is it easy to push the light switch?
Is it safe to use?
Does it function right? Is there a dimmer on the light? Can a user do much with it?
Is it easy to learn to use?
Is its usage easy to remember?
User experience: larger, usability is a part of user experience
- How do people experience a specific product (enjoyment and satisfaction, attractive
name, elegant)
Wanted aspects, unwanted aspects
Usability & user experience
Differences: potential conflicts (can a product be enjoyable as well as safe)
Different goals and how to measure these (not always overlapping)
The design of everyday things
Daily challenges: do you use all functions of devices?
Slide projector: only 1 button (next slide, short click, previous slide, long click)
Telephone sets (landline phone): transfer a call? Adjust the volume?
Usability concepts
Affordances perceivability of an objects to see if you can use such a thing without
explanation (push a light button, push a door handle), visual affordances (icons that are self-
explanatory), without affordance (what are these things doing there): with affordance (this
explains the usage)
Physical & virtual affordances
If a simple objects like a door needs instructions, then it probably indicates a poor design.
- Make the method of use visible
- Use a conceptual model
, Conceptual model how we understand how things works without understanding its
precise operation (because it is not necessary), people make their own image of how
something works.
- Car/computer
- Traffic lights: how often or how long do you press the button?
- Thermostat: do you turn up your heating to get it warm quicker?
Visibility hidden functions lead to problems (when number of functions is greater than
number of buttons)
With visible functionality, the user can directly use all functions
Example: bathroom buttons (hot/cold, on/off)
Mapping relationship between the button you press and the result of that
Light switch dilemma: which button controls which lamp?
Size = value (money)
Feedback let a user know what is happening (beep, light, display, loading bar etc.), can
also be a physical change (turned knob, flames)
Constrains Limitation of the number of possible actions, prevent selection of wrong
options
Physical objects often have constrains: most keys can only be inserted in a lock in one way,
differences of cable input/output
Software constrains: inactive options in menus
Logical or ambiguous?
www.baddesigns.com
Consistency design interfaces with similar functions and elements for similar tasks (easier
to use and remember) ctrl-button.
There are often too many functions that can be connected this increases the risk of
making errors
Internal/external consistency
Internal: operations behave the same within an application
External: operations, interfaces are similar in several applications and machines
Keypad numbers layout: example of external inconsistency
Both are conventions, but they are not consistent
Conventions accepted norms of standards
Can be artificial, arbitrary, or learned
Often determined by culture
Use conventions with respect, violate them only with great risk
