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Interaction Design and Final Exam Review Session 13
LBSC 790 / INFM 718B
Building the Human-Computer Interface
Agenda
Questions
Interaction Design
Final Exam Review
Applets (time permitting)
Interaction Design
Rapid prototyping process
Evaluate Refine
Design
Specification Identify needs/
establish
requirements Build
Prototype Final specification Exemplifies a user-centered design approach Start
Interaction Design
Play to the strengths of machine and human
Place the locus of control with the user
Make it easy to do the right thing
Support multiple interaction styles
Conceptual models
How the system will appear to users
A conceptual model is a high level description of:
“the proposed system in terms of a set of integrated ideas and concepts about what it should do, behave and look like, that will be understandable by the users in the manner intended”
Conceptual model and User understanding
Design Model User’s Model System Image SYSTEM DESIGNER USER Design Model
How designer thinks system should work
System Image
How system works
User Model
How user thinks system works
Ideal = all map
Poor system image = poor understanding
Conceptual models based on activities
Giving instructions
issuing commands using keyboard and function keys and selecting options via menus
Conversing
interacting with the system as if having a conversation
Manipulating and navigating
acting on objects and interacting with virtual objects
Exploring and browsing
finding out and learning things
Conceptual models based on objects
Usually based on an analogy with something in the physical world
Capitalize on familiarity
Understanding of:
Kinds of activities application would support
Problems with current tools trying to achieve these activities
Examples include books, tools, vehicles
International Children’s Digital Library
http://www.icdlbooks.org
Interface Metaphors
Interface designed to be similar to a physical entity but also has own properties
e.g. desktop metaphor, web portals
Can be based on activity, object or a combination of both
Exploit user’s familiar knowledge, helping them to understand ‘the unfamiliar’
Conjures up the essence of the unfamiliar activity, enabling users to leverage of this to understand more aspects of the unfamiliar functionality
Break conventional rules
Too constraining, Can limit designer’s
imagination, Transfer bad parts from
existing designs
Conceptual model and User understanding
Design Model User’s Model System Image SYSTEM DESIGNER USER Design Model
How designer thinks system should work
System Image
How system works
User Model
How user thinks system works
Ideal = all map
Poor system image = poor understanding
Mental models
Users develop an understanding of a system through learning & using it
Knowledge is often described as a mental model
How to use the system (what to do next)
What to do with unfamiliar systems or unexpected situations (how the system works)
People make inferences using mental models of how to carry out tasks
Mental models
How deep is your mental modal of a VCR remote control? Craik (1943) described mental models as internal constructions of some aspect of the external world enabling predictions to be made
Involves unconscious and conscious processes, where images and analogies are activated
Deep versus shallow models (e.g. how to drive a car and how it works)
Everyday reasoning & mental models
You arrive home on a cold winter’s night to a cold house. How do you get the house to warm up as quickly as possible? Set the thermostat to be at its highest or to the desired temperature?
You arrive home starving hungry. You look in the fridge and find all that is left is an uncooked pizza. You have an electric oven. Do you warm it up to 375 degrees first and then put it in (as specified by the instructions) or turn the oven up higher to try to warm it up quicker?
Heating up a room or oven that is thermostat-controlled
Many people have erroneous mental models (Kempton, 1996)
Why?
General valve theory, where ‘more is more’ principle is generalised to different settings (e.g. gas pedal, gas cooker, tap, radio volume)
But: Thermostats are based on model of on-off switch
Core abstractions about how things work
Heating up a room or oven that is thermostat-controlled
Same is often true for understanding how interactive devices and computers work:
Poor, often incomplete, easily confusable, based on inappropriate analogies and superstition (Norman, 1983)
e.g. frozen cursor/screen - most people will bash all manner of keys
Design principle of transparency
• Useful feedback
• Easy to understand
• Intuitive to use
• Clear, easy to follow instructions
• Appropriate online help
• Context sensitive guidance when stuck
• NOT literally
Help users develop appropriate mental models
Key points
Fundamental aspect of interaction design is to develop a conceptual model
Interaction modes and interface metaphors provide a structure for thinking about which kind of conceptual model to develop
Interaction styles are specific kinds of interfaces that are instantiated as part of the conceptual model
Interaction paradigms can also be used to inform the design of the conceptual model
Transparency helps users develop mental models
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