1. HCI What ? HCI Why ?
What happens when a human and a computer system interact to perform a task?
task -write document, calculate budget, solve equation, learn about Bosnia, drive home, make a reservation, land a plane...
Why is this important?
1.Computer systems affect every person
2.Safety, satisfaction, utility is critical
3.Product success depends on ease of use

2. Goals of HCI Allow users to carry out tasks Safely Effectively
Efficiently
Enjoyably

3. Usability Crucial issue in this area! Combination of Ease of learning
High speed of user task performance
Low user error rate
Subjective user satisfaction
User retention over time

4. HCI How? How do we improve interfaces?
1.Educate software professionals
2.Draw upon fast accumulating body of knowledge regarding H-C interface design
3.Integrate UI design methods & techniques into standard software development methodologies now in place

5. UI Design/Develop Process
Tao (source) of User-Centered Design
Analyze user’s goals & tasks
Create design alternatives
Evaluate options
Implement prototype
Test
Refine

6. Above All Else… Know the User!
Physical & cognitive abilities (& special needs)
Personality & culture
Knowledge & skills
Motivation
Two Fatal Mistakes:
1.Assume all users are alike
2.Assume all users are like the designer

7. Design Evaluation “Looks good to me” isn’t good enough!
Both subjective and objective metrics
Some things we can measure
Time to learn
Speed of performance
Rate of errors by user
Retention over time
Subjective satisfaction

8. History of HCI Digital computer grounded in ideas from 1700’s & 1800’s
Technology became available in the 1940’s and 1950’s
The “user” concept is relatively new

9. Human Role How is human viewed in HCI What is human role?
Different roles engender different

10. Human as… 1. Sensory processor Experimental psych, sensory psych
e.g. Model-Human Processor (Card, Moran & Newell)
2. Interpreter/Predictor
Cognitive psych, AI
e.g. Distributed cognition (Hutchins)
3. Actor in environment
Activity theory, ethnography, ecol psych
e.g. Situated action (Suchman)
e.g. Activity theory (Vygotsky, Nardi)

11. What Makes a System Usable
Usability results when the system…
Sensory processor -Fits within human limits
2. Interpreter/Predictor -Fits with knowledge
3. Actor in environment -Fits with task and social context

12. Two Views of Interaction
Interaction with
Software system is a tool or machine
Interface is a usability-engineered membrane
Human-as-processor & -interpreter models
Interaction through
Software is a medium used to interact with task objects or other people
Interface plays a role in social context
Human-as-interpreter & -actor models