Chapter 4 Cognitive Engineering HCI: Designing Effective Organizational Information Systems Dov Te’eni Jane M. Carey

Copyrights Te'eni & Carey Chapter 4 Cognitive Engineering Context in the Book  Chapters 2 & 3 look at the resources of HCI (Human Computer Interaction)  Human information processing system  Interactive technologies  This chapter focuses on how these resources could be used to accomplish a task  Looks at the triad relationship between user, computer, and task

Copyrights Te'eni & Carey Example of 3 generations of word processors – Example 1 is a line-based text editor that requires separate typed commands to control spacing, etc. and memorization of commands (like.SP 2 to double space) – Example 2 is key stroke oriented that requires control keys plus letters to format a document (like Ctrl/U for underline – Example 3 is a WYSIWYG (what you see is what you get) to format, you point and click to select parts of text and actions (like highlight text and select and click on FORMAT/ Paragraph/Line Spacing/Double OK) Chapter 4 Cognitive Engineering

Copyrights Te'eni & Carey Chapter 4 Cognitive Engineering - Synopsis UserComputer Task (Write report) Triad of User, Computer, and Task

Copyrights Te'eni & Carey Chapter 4 Cognitive Engineering When is HCI a positive or negative experience? Guidelines for good interface design - Consistency (acts the same way every time) - Stability (does not abort) - Use of metaphors (to anchor mental models, e.g. trash can for deleted files) - Provide feedback (instructions, verifications, corrections) - Direct manipulation (versus keystrokes) - WYSIWYG (What you see is what you get) - See and point (versus explain) - Aesthetic integrity (pleasing and recognizable)

Copyrights Te'eni & Carey Chapter 4 Cognitive Engineering The complexity of human-computer interaction (HCI) – Cognitive engineering combines cognitive psychology (how the brain works) and information technology (how the computer works) to support task completion – Tasks are a set of intentions and evaluations

Copyrights Te'eni & Carey Chapter 4 Cognitive Engineering Figure 4.4 HCI as a bridge between human and computer

Copyrights Te'eni & Carey Chapter 4 Cognitive Engineering Three views of the user’s perceptions of difficulty 1. Accomplishing a task with no computer support 2. Operating a computer with no specific task in mind 3. Using a computer to accomplish a specific task The goal is to minimize the complexity of the combined task

Copyrights Te'eni & Carey Chapter 4 Cognitive Engineering Example (fill up a bath tub so it is the correct temperature and the correct level) Adjust 2 valves (hot and cold taps) Both valves affect temperature and rate of flow Difficult to relate the physical valves to the psychological variables Goal of the designer is to improve performance by creating an effective design (in the case of the bath tub, an effective design is the single tap that combines flow rate and temperature at the same time)

Copyrights Te'eni & Carey Chapter 4 Cognitive Engineering An effective design bridges the gap between the human and the computer by a sequence of user activities Gaps signify the distance between our internal goals and expectations and the external representation of states and control devices Norman’s 7 stage model of user activity

Copyrights Te'eni & Carey Chapter 4 Cognitive Engineering Norman’s 7 stage model of user activity

Copyrights Te'eni & Carey Chapter 4 Cognitive Engineering Task Decomposition (7 activities)  Establish a goal  Form the intention of accomplishing that goal  Specify the action sequence needed to accomplish the  goal  Execute the action  Perceive the results  Interpret the system state  Evaluate (compare results to intentions)

Copyrights Te'eni & Carey In the case of the 3 word processors, the gap between the actions and the execution and evaluation go from longer to shorter in each successive type Reducing the complexity (the gaps) of the human-computer interactions is an important goal in every aspect of HCI design When applying Norman’s 7 stage of activities model it is important to recognize the cycle of abstract to concrete and concrete to abstract Chapter 4 Cognitive Engineering

Copyrights Te'eni & Carey Norman’s model (move from abstract to concrete and back to abstract) – Intentions are abstract – Action specification becomes more concrete – Execution is very concrete – Perceptions of the execution are a little less concrete – Interpretation is more abstract – Evaluation is very abstract Chapter 4 Cognitive Engineering

Copyrights Te'eni & Carey Example (Profit/Loss for Pencil Sharpener Sales) 3 variables – Volume of sales – Price – Interest Rate Goal (intention) is to examine sensitivity of profit to changes in interest rate Execution - Manipulate the interest rate in the spreadsheet and watch what happens to the profit Perceive the changes Interpret and evaluate the changes Chapter 4 Cognitive Engineering

Copyrights Te'eni & Carey The GOMS (Goals, Operators, Methods, and Selection rules) model Card, Moran, & Newell, 1983) – A language supports the GOMS model and is called Natural GOMS Language (NGOMSL) – See figure for flowchart Chapter 4 Cognitive Engineering

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Chapter 4 Cognitive Engineering It’s not just a mental process – muscles (motor) and perception (eyes) are involved too

Copyrights Te'eni & Carey Chapter 4 Cognitive Engineering Describing HCI for simple tasks – Using GOMS for simple information – See Graph reading example – Figure a line graph showing sales over time for companies ABC and XYZ. Which had the highest growth rate between 1994 and 1996?

Copyrights Te'eni & Carey Chapter 4 Cognitive Engineering Errors – Information Processing can be skill-based, rule- based, or knowledge-based (Rasmussen, 1986) which require more and more cognitive resources as you move from skill to rules to knowledge – Skills are routine – Rules can be applied to problem solving of structured problems – Knowledge can be applied to ill-structured problems

Copyrights Te'eni & Carey Chapter 4 Cognitive Engineering Skill-based errors are the result of inattention (lapse in concentration) or over attention (too much self monitoring that results in loss of flow) Rule-based errors are the misapplication of good rules or the application of bad rules Knowledge-based errors are the result of limited cognitive resources or inaccurate representations of the problems

Copyrights Te'eni & Carey

Chapter 4 Cognitive Engineering User-centered design principles – Know your user – Assess system usability – Match the system to the mental models of the user and the designer Understand the “trinity” of the user, designer, system

Copyrights Te'eni & Carey User Designer System User-Designer-System Trinity