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

Chapter 4Cognitive Engineering

HCI:

Designing Effective Organizational Information Systems

Dov Te’eni

Jane M. Carey

Copyrights Te'eni & Carey


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


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


Chapter 4Cognitive Engineering - Synopsis

UserComputer

Task (Write report)

Triad of User, Computer, and Task



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)



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



Figure 4.4 HCI as a bridge between human and computer



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



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)



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



Norman’s 7 stage model of user activity



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)


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



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



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



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






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



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



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



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




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


User

Designer

System

User-Designer-System Trinity

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