7- Evaluation and HCI Models Intro Flashcards
What are the goals of evaluation?
- Test a hypothesis, usability and functionality of a system.
- Asses effects of interface and interaction design on user.
- Identify specific problems.
What are the four key questions to keep in mind?
- Are users thinking what the designers thought they’d be thinking?
- Will users see the control (button, menu, switch, etc) for the action?
- Once users find the control, will they recognize that it produces the effect they want?
- After the action is taken will users understand the feedback they get, so they can go on to the next action with confidence?
How do we ‘debug’ a design?
Using Heuristic Evaluation (A set of rules, not specific guidelines)
What are examples of design heuristics?
1- Visibility of System status (Give appropriate feedback of what is happening)
2- User control and freedom (support undo, redo help users leave an unwanted state caused by mistakes.
3- Aesthetic and minimalist (Dont show irrelevant information)
4- Efficiency of use (Have shortcuts, make system efficient for different experience levels)
5- Help & documentation (make help and documentation easy to find and search in)
6- Real world to system mapping (use real world words/concepts in a natural and logical order)
7- Error prevention (eliminate error prone conditions or check them before user commits to an action)
8- Consistency (Follow platform conventions)
9- Recognition vs Recall (dont make users rely on memory to navigate stuff, make it easy to recognize the flow)
10- Error recovery (Show errors in plain english text, no code numbers, and suggest causes and solutions)
What are the four types of evaluation? Briefly explain and mention any pros and cons.
1- Self-guided: Open-ended exploration
+ Good for exploring different aspects of the interface and following potential pitfalls
- Not task-directed
2- Scenario exploration: Step through the interface using specific user tasks.
+ Ensures problems are identified in relevant portions of the interface.
+ Ensures that specific features of interest are evaluated
- Limits the spoke of evaluation, problems can be missed.
3- Review based: Results from literature used to support or refute parts of the design
+ Do not need to find or schedule users.
+ Fewer ethical issues to consider because no users are involved.
- Need to be careful that results are transferable to the new design.
- Finding good experts and building consensus between them can be hard.
4- Model-based: Cognitive models used to filter design options
+ Do not need to find or schedule users.
+ Fewer ethical issues to consider because no users are involved.
- Can be hard and expensive to find experts
- Experts can have their own bias, no users are involved, and experts are not real users, how valid is their opinion?
What is Jakob’s law of internet user experience? Whats its implication?
“Users spend most of their time on websites other than yours”.
Therefore, a big part of users’ mental models will be influenced by information they gathered from using other websites. The implication is that people expect websites to act alike.
Why do people hit the button for elevators or pedestrian crossings at least twice?
Because the buttons don’t have good feedback and people are not sure if they made the right contact, or if they believe that it will make things go faster.
- The first button press may not have been recorded (perhaps you didn’t press the button correctly, or perhaps the system malfunctioned)
- Repeatedly pressing the button might increase the system’s awareness of the importance of the request and make light change faster or ensure priority for the elevator
What does GOMS mean and what are its pros & cons?
HCI model to predict the time it takes a person to perform a task on a computer.
Goals: The desired outcome that the person is trying to achieve.
Operators: Cognitive and physical actions a person has to take to achieve the goal (typing, clicking, reading, etc)
Methods: A sequence of operators to achieve a goal.
Selection rules: Criteria a person uses to choose which method to use.
+ Allows visibility of all procedural knowledge.
+ Easy to use
+ Can be used to compare different design alternatives
- Only applies to skilled users
- Lack of account for errors
- Mental workload or fatigue (unpredictable variables) are not adressed.
What is TLM?
The evolution of GOMS for mobile devices. Touch-Level Model.
Explain Fitt’s law for HCI.
Fitts’ law is a model of human-computer interaction that predicts the time it takes for a person to move to a target on a computer screen. It is based on the idea that the time it takes to move to a target is a function of the distance to the target and the size of the target.
