CS228 HumanComputer Interaction

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CS228 Human-Computer Interaction
How do we begin thinking about creating
interactive technology?
PACT (P)eople conducting (A)ctivities in a
(C)ontext using (T)echnology. Design - how to
do it Technologies - what can technology do?
What content does something have? People - who
will use it, who will be affected by
it? Activities and contexts - what will people
have to do in what circumstances?
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CS228 Human-Computer Interaction
How do we begin thinking about creating
interactive technology?
PACT (P)eople conducting (A)ctivities in a
(C)ontext using (T)echnology.
Exs Teenagers send text messages to
friends People hold a videoconference Someone
turns on their robot floor cleaner
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CS228 Human-Computer Interaction
Another view of the feedback nature of
human-technology interaction
Requirements
Activities in context
Technologies
People
Opportunities
(source after Carroll (2002))
Requirements is information about what the
interactive system should do, and how it should
do it. Technologies create new opportunities
new activities for people to carry out, and new
ways for people to interact with one another. Q
What would be some requirements for A
videoconferencing system that can be used in
outdoor environments? A robotic floor
cleaner? Q What new kinds of human-human
activities might outdoor videoconferencing allow?
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CS228 Human-Computer Interaction
(P)eople differ from one another along different
dimensions Physical differences Different
abilities in the five senses Differing motor
control abilities Different body shapes, sizes
and colors. Psychological differences Different
cognitive biases Spatial / temporal
awareness Cultural differences Language
differences English reads left to
right Hebrew, Arabic reads right to
left From www.i18nguy.com/MiddleEastUI.html
Cognitive differences What people expect
system to do next mental model Usage
differences Differing experience
levels novices use the mouse pros use keyboard
shortcuts Discretionary users use
the technology only if really necessary
First Prev Next Last
? ? ? ?
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CS228 Human-Computer Interaction
(A)ctivities have a purpose, and a number of
features

• 1. How regular or infrequent is the activity
  undertaken?
• 2. Usage history smooth, or peaks and troughs?
• 3. Continuous vs. interrupted how to find your
  place again?
• 4. Response time
• 5. Can be done by one, or more people?
  (Coordination/cooperation)
• 6. Well-defined or vague? Sequential or
  exploratory design needed?
• Safety-critical? Lots of feedback, explicit
  timing, etc.
• 8. How are mistakes, errors and omissions
  handled?
• Data requirements
• Large/small? Streamy (video,speech)? Chunky
  (icons/text)?

Temporal aspects
Cooperation
Complexity
Safety
Nature of the content
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CS228 Human-Computer Interaction
The parable of Tempus and Hora
There once were two watchmakers, named Hora and
Tempus, who made very fine watches. The phones in
their workshops rang frequently new customers
were constantly calling them. However, Hora
prospered while Tempus became poorer and poorer.
In the end, Tempus lost his shop. What was the
reason behind this? The watches consisted of
about 1000 parts each. The watches that Tempus
made were designed such that, when he had to put
down a partly assembled watch (for instance, to
answer the phone), it immediately fell into
pieces and had to be reassembled from the basic
elements. Hora had designed his watches so that
he could put together subassemblies of about ten
components each. Ten of these subassemblies could
be put together to make a larger sub-assembly.
Finally, ten of the larger subassemblies
constituted the whole watch. Each subassembly
could be put down without falling apart.
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CS228 Human-Computer Interaction

• THERAC-25
• Worst computer error in history
• Killed five people
• injured many more
• More details
• Wired News, Nov. 8/2005
• History's Worst Software Bugs

X-Ray gun
X-ray beam
X-Ray shield
Specification of actions 1. Command to move
shields. 2. Shields move. 3. Command to fire
gun. 4. Gun fires
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CS228 Human-Computer Interaction
Three kinds of (C)ontexts
Physical environment Where is the technology?
Indoors/outside? Noise levels? Crowded
(private)? Internet access slow in the country,
fast in the city. Social context Is the
environment supportive? (Manuals, experts at
hand?) Sound output not in an open-plan office,
but OK in a cubicle. Organizational
context Changes in technology impact the
structure of companies, cultures, law, nations,
social institutions, etc. One technology may
create jobs in company X, but destroy jobs in
company Y.
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CS228 Human-Computer Interaction
What makes up a (T)echnology?
Input What kind of data is coming in? How much,
how often? Input devices appropriate to the
data. Exploitation of input devices to broaden
information conduits (eg. a moving videocamera
can pick up depth information) Output Streamy
(video,speech) vs. chunky (icons/text) output
data Chunky data has persistence (does not need
to be remembered) Streamy data is more engaging
(attracts users) Communication What other
technologies and people should it communicate
with? How? How often? How much
bandwidth? Content (internals) What data is
contained within? What data is shared? How many
software components, how are they
connected? What algorithms are employed? How
visible is the data/algorithms to the user?
Should it be?
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CS228 Human-Computer Interaction
BitTorrent Large software system (millions of
computers) Large amounts of data (legal/illegal
software/media) Overcomes bottleneck of new,
large, rare data instance Instance broken up
into pieces Computers are both Servers
(supply pieces) and Clients (request
pieces) Who is responsible for illegal
content? No clear provider.
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CS228 Human-Computer Interaction
In-class exercise Performing PACT analysis
Sketch out a technology create T in response to
P, A, and C.
1. People want to visualize BitTorrent across the
Internet Who has what? Which parts are rare?
Where are they? 2. A store in a mall wants to
scan the shopping bags carried by consumers
walking by outside, and change the content
advertised in their storefront accordingly. 3.
Homeowners want a robot that can paint indoor
walls. 4. A set of wireless sensors should be
deployed in a rainforest to measure
environmental variables over a two-year period.