What is HCI?

Human-Computer Interaction (HCI) includes user-centered design (UCD).

These points are adapted from the ACM SIGCHI statement (see pp. 3-4 in the text):

• Design, evaluate and implement interactive computing systems for human use
• Study phenomena surrounding human use of interactive systems

Goals of Human-Computer Interaction

• Create usable software-enabled products and user-interfaces
• Enhance the usability of existing products
• Identify problems and tasks (such as in the workplace) that can be addressed with software products

Dimensions of usability

Our text cites the list used by Eason (1988):

• Safety (also consider security)
• Utility (sometimes call usefulness)
• Effectiveness (too vague and general to be helpful)
• Efficiency
• Usability (often this term refers to the whole list, learnability is a better term)
• Appeal (aka user satisfaction, likeability, attitude)

Effectiveness seems to be one of the most abused usability terms. Often practioners use the term usability to refer to all user-centered design goals. For this course, we will generally focus on the following dimensions:

• Utility
• Learnability
• Efficiency
• User satisfaction

HCI practitioners need to be mindful of other practical considerations when designing their products. These include the impact of legacy systems, portability and reliability.

Discussion items:

• What are examples of software-enabled interactive products?
• Identify products with usability problems. To which usability objectives (i.e. learnability, efficiency, etc.) do the problems correspond?
• Often usability objectives have inherent tradeoffs. What are examples? For example, in which situations might improving learnability negatively affect efficiency?
• How might we measure the dimensions of usability?
• Here's a picture of a bathroom light switch in a residential home. The switch on the left (nearest to the door) controls the light above the sink. The switch on the right controls the light over the bathtub, which is on the other side of the room from the sink. Is this a good design? What usability measures matter? Under what circumstances?