1 CMT 3210: Understanding the human element in HCI Week 10: External cognition - Designing external representations Elke Duncker / Paola Amaldi-Trilló.
Post on 20-Jan-2016
219 Views
Preview:
Transcript
1
CMT 3210: Understanding the human element in HCI
Week 10: External cognition- Designing external representations
Elke Duncker / Paola Amaldi-Trilló
2
Topics
Cognition as involving external and internal structures and processes
External representations that support cognitionWhen and how to design external
representations
3
The story so far….
Design of information displays on the basis of characteristics of human perception Feedback to support the development of mental models for interpretation, evaluation, decision making and
learning
How can we make tasks easier by using certain formats for representing information?
Relationship between type of task and type of information displayed?
4
Example: a game
Two playersnumbers 1, 2, 3, 4, 5, 6, 7, 8, 9Each player takes a number each turn. This
number is no longer available.The game continues until all numbers have
been taken or until one of the players has three numbers that add up to 15.
The first player with three numbers that add up to 15 wins.
5
How to turn it into an easier taks:
2 7 6
9 5 1
4 3 8
6
Example: Calculation
Calculations in navigation: A ship travels 1500 yards in 3 minutes. What is its speed in knots?
How is this done?use
Pen, paper, Calculator, 1 nm = 2000 yards, 1h = 60 min, D = ST “Three scale nomogram” “Three minute rule”
7
Using pen and paper
Required knowledge: 1 nm = 2000 yards, 1h = 60 min, 1 knot = nm/h, Speed = Distance/Time
speed = (1500 yards) / (3 min)= (1500 : 2000 yards) / (3:60 min)= (1500/2000) * (60/3)= 15 knots
8
Using a calculator
Required knowledge: 1 nm = 2000 yards, 1h = 60 min, 1 knot = nm/h, Speed = Distance/Time
Calculator steps: 60 / 3 = 20 result * 1500 = 30000 result / 2000 = 15 answer: 15knots seems easier, but you have to know what you are doing
before you start.
9
Using a three scale nomogram
Specialised external artefactOptimises distance / speed / time calculationsSimplifies the organisation of the task
10
The Three Minute Rule
Specialised internal artefact
Tailored for use in navigation
Time interval, units and task fit together
1500 yards in 3 minutes. Speed in knots?
Number of hundreds of yards travelled in three
minutes
=
speed in knots
Answer = 15 knots
11
Theory
How do these devices work?Need to look beyond human information
processing psychology which focuses on characteristics of individual cognition cognitive system of person plus external
representations External representations are converted by some
cognitive mechanisms into internal representation
12
Theory (2)
External Cognition look outside the head of the individual. The unit of
analysis is the human-machine system
cognitive process involve the co-ordination of internal and external structures among individuals. What does individual cognition become when it is
shared between individuals?
13
External distributed cognition
Individuals performing a task
External resources
e.g. calculator, peers, team
notes, manuals,diaries.
Internal devices
specific rules,memorized calculation
stables,formulae
Distributed Cognition
14
Mechanisms of external cognition
External memory memory the composition of internal memories and
external representations
Computational offloading computations and cognitive tasks can be “pre-calculated”
and embedded in external representations
Transformation from cognitive into perceptual tasks form of external representation can transform hard
mental operations into easier perceptual ones
15
External memory
External artefacts often used to enhance internal human memory
Often created specially for the purpose of remembering
Memory function relies on the combination of internal and external components
Examples?
16
Example
“Speed bugs” markers set by pilot to
indicate desired speed
Serve as a memory reducing the burden on
internal memory
Many similar external memory aids in computer systems and “real life”
237.4
17
Computational offloading
Reduce cognitive effort by choosing representations that transform tasks into simpler, but equivalent ones
Example: Multiply 1011(2) by 10(2) either: 11(10) x 2(10) (external representation changes)
or shift to left by one digit 1011 x 10 = 10110 (internal specific rule applied)
More examples?
18
From cognitive to perceptual tasks
Perceptual inferences can allow users to easily gain information about: distance and proximity size spatial coincidence colour etc.
Perceptual operations often easier and quicker than other cognitive operations
19
Perceptual inferences
The history of use is available in many ways. It informs our interactions with artifacts. For ex., well-used pad on the door new paperback most recently used papers seating on top of the pile
20
Example
Which display shows the larger value? Which type of display makes the comparison
easiest?
22.7 77.2
A B A B
Graphical Digital
21
Example: airline information
HTR
MEX
DUS
COL
CHG
LAX
MEX DUS COL CHGLAXHTR
Users task: find cheapest flight
Cost represented by size Cost judgements
achieved by perceptual operation
22
Example: statistical data
User’s task: compare female student results to male student results. Who is more successful?
Numbers and results represented graphically
Comparison achieved perceptually
Comparison of Grades
0
2
4
6
8
10
12
14
16
grade
no o
f stu
dent
s
girls boys
23
Summary: Designing external representations
Support external memories offer external memory functions allow users to create them
Find ways of “pre-computing” make relationships explicit in representations
Choose representations that simplify cognitive work
Choose representations that support perceptual operations rather than cognitive ones
24
Further reading
Scaife, M. & Rogers, Y. (1996) External Cognition: How Do Graphical Representations Work? Int. Journal. of Human-Computer Studies, 45, 185-213
Casner, S. (1991) A Task Analytic Approach to the Automated Design of Graphic Presentations. ACM Trans. on Graphics. 10(2).
25
Further readings
Hollan, J., Hutchins, E., & Kirsh, D. (2001). Distributed cognition: Towards a new foundation for human-computer interaction research. In J.M. Carroll (ed.) (2001) Human-computer interaction in the new millenium. Addison-Wesley.
Hutchins, E. (1996) Cognition in the Wild. MIT Press.
Jiajie Zhang's papers: http://acad88.sahs.uth.tmc.edu/
top related