Chapter 4 Cognitive Engineering HCI: Designing Effective Organizational Information Systems Dov...
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Chapter 4Cognitive Engineering
HCI:
Designing Effective Organizational Information Systems
Dov Te’eni
Jane M. Carey
Copyrights Te'eni & Carey
Chapter 4Cognitive 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 4Cognitive Engineering - Synopsis
UserComputer
Task (Write report)
Triad of User, Computer, and Task
Copyrights Te'eni & Carey
Chapter 4Cognitive 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
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Chapter 4 Cognitive Engineering
Figure 4.4 HCI as a bridge between human and computer
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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
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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)
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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
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Chapter 4Cognitive 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
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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 4Cognitive Engineering
It’s not just a mental process – muscles (motor) and perception (eyes) are involved too
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Chapter 4Cognitive Engineering
Describing HCI for simple tasks– Using GOMS for simple information– See Graph reading example
– Figure 4-11 1 a line graph showing sales over time for companies ABC and XYZ. Which had the highest growth rate between 1994 and 1996?
0
20
40
60
80
100
120
1993 1994 1995 1996
ABC
XYZ
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Chapter 4Cognitive 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
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Chapter 4Cognitive 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
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Chapter 4Cognitive 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