Transcript Chapter 3 – Human Information Processing

Chapter 3 – Human Information
Processing
HCI: Designing Effective
Organizational Information Systems
Dov Te’eni
Jane Carey
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
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
Figure 3.1 Objectives and Actions in
Preparing a Word Processing Document
Objectives
Setup File
Save File
Determine
Layout
Open Document
Name the File
Set top/bottom
Margins
Print File
Actions
Set Left/Right
Margins
Set Print Options
Steps in preparing a word-processed
Step 1. Open a new file
document
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.
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
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
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Sensation
Perception
Decision
Response Execution
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
Inputs
Outputs
Chapter 3 - HIP
Figure 3.2 Stages of Information Processing
Stages of HIP
Memory
(Attention)
Working
Memory
Long-term
Memory
Processors
Perception
Touch/Feeling
Identification
Location
Cognition
Translation
Operation
Decision
Motor
Translation to
Action
(Keyboard,
Mouse)
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
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 10-20
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
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)
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
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
3.4 Watson and Johnson-Laird (1966)
Logical Reasoning Experiment
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Chapter 3 - HIP
Cognitive processing is not uniform and depends
on:
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Task requirements
User familiarity with task (automatic or controlled)
Type of information (verbal or image)
Heuristics
Chapter 3 - HIP
Memory and Processing
– The role of memory is critical and must be examined
– Working memory
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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
Chapter 3 - HIP
Long-term 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)
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)
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
Chapter 3 - HIP
More principles
– 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)
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
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, problemsolving and mechanism
Knowledge of the
Problem
Knowledge of the computer
(documentation,
software,
hardware)
Knowledge of the Context
bound to the system
Knowledge of the actions
of the system
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
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