1. Chapter 3 – Human Information Processing
HCI: Designing Effective Organizational Information Systems
Dov Te’eni
Jane Carey

2. Chapter 3 – Human Information Processing
Designing effective Human-Computer Interaction depends on understanding how humans process information
Key aspects of Chapter 3:
HIP model
Performance is a function of speed and accuracy
Context

3. Chapter 3 - HIP
Consider the task of editing a file using a computer which involves:
Controlled processing (versus automatic)
Goal-driven behavior (versus random)
Relationship between Controlled processes and goal-driven behavior
Example: trying to catch another driver while staying below the speed limit

4. Figure 3.1 Objectives and Actions in
Preparing a Word Processing Document
Setup File
Save File
Determine
Layout
Print File
Objectives
Actions
Open Document
Name the File
Set top/bottom
Margins
Set Print Options
Set Left/Right
Margins

5. Steps in preparing a word-processed document
Step 1. Open a new file
Step 2. Assign a name
Step 3. Set margins
Step 4. Set printer options
Step 5. Type text
Step 6. Insert figures
Step 7. Edit text
Step 8. Add cover page
Step 9. Spell check
Step 10. Change font
Step 11. Repeat until satisfied
Step 12. Print
Step 13. Save file
This task is difficult to turn into an automatic process due to complexity and sub-goals and therefore will remain a controlled process.

6. Chapter 3. HIP What are the implications for design?
If a task is goal-driven and requires fast performance, the designer should guide the user with a sequence of actions that build toward the goal
In the case of the word processor, some default parameters can be set to minimize the work on the part of the user which in turn speeds up the task
Knowledge of HIP allows a designer to draw design implications

7. Chapter 3 - HIP
This book will draw on several cognitive models including:GOMS (Goals, Operators, Methods, Selection Rules) by Card, Moran, Newell
A rough model of Human Information Processing (HIP)
Stages of IP
Sensation
Perception
Decision
Response Execution

8. Chapter 3 – HIP The HIP view of the user
An information system that accepts inputs from the external world and produces responses directed out to the external world
Outputs
Inputs

9. Chapter 3 - HIP Figure 3.2 Stages of Information Processing
Stages of HIP
Memory
(Attention)
Processors
Perception
Cognition
Motor
Working
Memory
Long-term
Memory
Translation to
Action
(Keyboard,
Mouse)
Translation
Operation
Decision
Touch/Feeling
Identification
Location

10. Chapter 3 - HIP Figure 3.2 Explanation
The perceptual processor senses, detects, and accepts inputs from the external world and stores parts of the perceptions in working memory (these are visual or auditory)
The cognitive processor interprets, manipulates, and makes decisions about the inputs (along with memory)
The motor processor generates physical actions (such as keying and mouse clicking) based on perceptions and cognitions

11. Chapter 3 - HIP Figure 3.2 Explained (cont.)
All these parts interact with each other
The idea of performance (speed and accuracy) is introduced
HCI Designers try to implement designs that make the interface usable and increase performance
Some constraints
Working memory capacity is 7+ 2 chunks for seconds
Cycle time of processors around 100 milliseconds (with motor being the slowest)
Long-term memory capacity is almost unlimited, but difficult to retrieve from

12. Chapter 3 - HIP Design implications
User will not notice screen changes within screen changes
User perception is limited to 7+ 2 chunks of information and will ignore part of the screen
Long-term memory retrieval will significantly degrade performance
Designs must reflect these issues
Additional impacts include: motivation to use, practice, and attributes of representation (such as intensity)

13. Chapter 3 - HIP Perceptual Processor
Works tightly with perceptual storage
3 principles of relevance
Input buffers of the working memory store visual and auditory images
Perceptual processor works in cycles (pulses combined to make 1 signal)
More intense signals require less time to process

14. Chapter 3 - HIP Cognitive Processor
Cognitive processors are automatic (fast and undemanding) or controlled (slower and demanding)
Cognitive Processors can process both images and verbal (text) information (but differently)
Cognitive processing is not always consistent over time and is content-related

15. E K 4 7 $10 $30 3.4 Watson and Johnson-Laird (1966)
Logical Reasoning Experiment E K 4 7
$10
$30
No signature
Signature

16. Chapter 3 - HIP Cognitive processing is not uniform and depends on:
Task requirements
User familiarity with task (automatic or controlled)
Type of information (verbal or image)
Heuristics

17. Chapter 3 - HIP Memory and Processing
The role of memory is critical and must be examined
Working memory
Limited capacity and retention time
Stores both images and verbal information (text)
Task complexity is related to forgetting and interference
Order is important in verbal storage
Rehearsal can increase remembrance
Working memory interacts with long-term memory

18. Chapter 3 - HIP Long-term memory Organizing Memory
Is episodic(direct memory) or semantic(meanings)
Individual differences come into play (age for example, can negatively impact memory capacity)
Organizing Memory
Schemata (high order cognitive structures such as scripts)
Metaphors (related to an already familiar concept, e.g., desk top as a metaphor for RAM)

19. Chapter 3 - HIP More organizing mechanisms
Mental model – mental representation
Heuristics – short cuts or rules of thumb (e.g., boys are more athletic than girls is a judgment by representativeness and may lead to erroneous conclusions)

20. Chapter 3 - HIP Principles of HIP and Memory
Different combinations of tasks and memory will trigger different cognitive processors
In simple tasks, performance (accuracy and speed) depends on heuristic processes and episodes
Complex tasks can use schemata (mental models, heuristics, metaphors) to increase performance
Unfamiliar tasks require the creation of new schemata which in turn slows down the performance

21. Chapter 3 - HIP More principles HIP in context
Heuristics is based on the salient (meaningful) task features
If the salient features provide a clear task structure then performance will be improved
Use familiar labels on screens
HIP in context
Context is essential to comprehension
Immediate context (what user was doing before looking at the current screen
Distant context (in which the task occurs (like choosing the right investment portfolio)

22. Chapter 3 - HIP Guiding principles of context
Context must be maintained during an interactive session
Stick with one mental model or metaphor
Continuity between screens helps maintain context
Figure 3.5 shows the Block Interaction Model of Morton, Barnard, and Hammond (1979) and helps explain how different sources of knowledge interact to affect the context of work

23. Figure 3.5 Block Interaction Model by Morton, Banner, & Hammond, 1979
Knowledge of the
Natural Language
Knowledge of the context
Knowledge of the domain
Knowledge of the Version
Knowledge of the process, problem-solving and mechanism
Knowledge of the
Problem
Knowledge of the Context
bound to the system
Knowledge of the computer
(documentation,
software,
hardware)
Knowledge of the actions
of the system

24. Chapter 3 - HIP Coding and Retrieving Coding (prior to storage)
Retrieval (from memory)
Observations
The more active you are in generating information items, the better your recall
Pictures are easier to recall than words
Recall “in context” is easier than “out of context”
Complex patterns are more difficult to recall than simple
Clues stored at the time of coding make recall easier
Aging reduces memory capacity

25. Chapter 3 - HIP Conclusions Models help our understanding of HIP (
Performance is a function of cognitive management, memory, processing, attention, and comprehension
Performance is speed and accuracy
We can use schemata to organize knowledge (mental models, metaphors, heuristics)
Comprehension is sensitive to context