ICS 463, Intro to Human Computer Interaction Design: 3. Perception Dan Suthers

The major points Work from ambiguous, incomplete and infeasible specifications to precise requirements Use representations as resources for conversation and as formal documentation Capture whole system; allocate to computer and humans later

Requirements Functional: what the system must do Data: information needed to do it Usability: acceptable level of performance and satisfaction

Functional Requirements Focus on what the system does –Multiple levels of abstraction –Common Notation: Dataflow diagrams & Data Dictionary Also capture Constraints –On the system –On the development process

Dataflow Diagrams Level 0: Context Diagram Level 1: Major subsystems/processes Level 2: Details of processes name Source/sink Dataflow Process Datastore

Dataflow Example

Comments on Dataflow Encourages abstraction away from physical processes Natural language scenarios (walkthroughs) may be needed to “bring to life” for users Dataflow may discourage object- centeredness (why?)

Data Requirements Focus on structure rather than processing Should also specify whole human- computer system Common notation: Entity Relationship diagrams Use notation for both conversations with users and documentation

Entity Relationship Diagrams (Chen, 1976) Entity Attribute Relationship

Another ER Example (Constantino)

Usability Requirements Learnability: time required to reach given level of performance Throughput: speed of task execution and error rates Flexibility: adaptability to changes in tasks and environments Attitude: acceptance by users Measurable?: table 19.3

Usability Analysis Task Analysis: cognitive requirements for users User Analysis: characteristics of those who will use the system Environment Analysis: physical and social We focus on Task Analysis (although it has recently been de-emphasized in favor of activities or work)…

Task Analysis Terms Goal: a state of a system that an agent wishes to achieve Devices: methods, tools, techniques Task: a structured set of activities using devices and undertaken to achieve a goal Action: a task that involves no control component

Hierarchical Task Analysis Decomposition of a high level task (goal) into constituent subtasks and actions image from O'Callaghan

Cognitive Task Analysis What knowledge is needed to complete a task and how it is applied. Various techniques: Model Human Processor, GOMS, Task Knowledge Structures, Task Action Grammar … Let’s look at GOMS example in text. (We won’t concern ourselves with all the variations)

Comments Capture whole human-computer system, not just part you expect to program; assign responsibility later Initial representations are a resource for conversations with users rather than “getting it right” Subsequently, representations are formal documentation Best representation? You decide!

Assignment 1: Convince Your Boss Write a one page “executive summary” style argument for why your software development company should commit to a user-centered design methodology at the outset of a new project. (If you wish, you may invent a scenario in which a particular kind of software is to be developed.) Choose one of the methodologies in Ch and argue for your choice. Write this as if it will be read by your boss. Hand in a printed one-page document to me by Sept. 20th. Also, post the argument on a web site and me the URL. (We will discuss in Kuka.)

Assignment 2: Spell Checking Comment: Consider sequential processing versus all instances of a lexical item 1. Question 19.1 p. 393: Develop a data flow diagram for spell checking 2. Question 19.5 p. 400: Develop an entity relationship diagram for spell checking 3. Write a scenario for its use. 4. Do you agree with the task analysis page 414? Draw your own version if not. 5. Write a paragraph on whether and how these notations are useful, and how these analysis activities should be coordinated (do them in the order in which they were presented? All at once?) Post as web page (will discuss in Kuka) and me URL by Sept. 26th, 6pm

Assignment 3: Choose a project Choose an application or problem for which you will design a user interface. This project may be done in groups. You are encouraged to first discuss your ideas with me via or office hours. Write a one-page description of the project, written as a memo to your boss requesting permission to undertake the project. Turn in hardcopy to me by Sept. 27th. Also post on a project web site and send me the URL.

Comments on HW Tools: –Everyone have powerpoint? –Other drawing tools? –Screen capture capture tools? –Prefix subject with “ICS463” –Clearly identify subject Web Site: –Preferably one that will stick around –I can host if necessary –Avoid frames, Java (for now) –Test in both IE and Netscape