Transcript HCI-Lecture09

Human Computer Interaction
Lecture 09
Interaction Paradigms
Window systems and the WIMP interface
 Humans can pursue more than one task at a time
 A personal computer which forced the user through all
of the tasks needed to achieve some objective from
beginning to end without any diversion was not
appropriate
 To be an effective partner, a PC needs to support
multiple threads of activity simultaneously
 A computer system needed to present the context of
each activity so that user can distinguish them
Window systems and the WIMP interface
 Solution: Separate the physical presentation of different
logical threads on display device
 The window is the mechanism for these physically and
logically separate display spaces
 windows, icons, menus and pointers now familiar
interaction mechanisms
 First appeared in 1981 –
Xerox Star first commercial
windowing system
Metaphor
 Relating computing to other real-world activity is
effective teaching technique
 LOGO's turtle dragging its tail
 file management on an office desktop (First time used by Xerox
Alto and Star)
 financial analysis on spreadsheets
 Keyboard use in word processor as a typewriter
 virtual reality – user inside the metaphor
 Problems
 some tasks do not fit into a given metaphor

Scanning a file for viruses
 cultural bias

It should not be assumed that a metaphor will apply across national
boundaries
Direct Manipulation
 Designers noted that their products were gaining
popularity as their visual content increased
 1982 – Shneiderman coined this phrase. He described
 visibility of objects
 incremental action and rapid feedback
 syntactic correctness of all actions
 replace complex command languages with direct actions (hence the
term “direct” manipulation)
 In 1984 – First Macintosh personal computer demonstrated
the inherent usability of direct manipulation.
Direct Manipulation
 Direct manipulation for the desktop metaphor requires
files and folders to be made visible representing
underlying files and directories
 The model-world metaphor
 What You See Is What You Get (WYSIWYG)
Multimodality
 Mode: a mode is a human communication channel e.g.
Visual, audio or haptic (touch)
 Multimodality means simultaneous use of multiple
channels for input and output
 A multi-modal interactive system is that which relies on
the use of multiple human communication channels.
 We can say that all interactive systems are multimodal
because all use at least two human channels i.e. Visual and
hepatic
Computer Supported Cooperative Work
(CSCW)
 CSCW is collaboration of individuals via computer
 Emerged with the advent of strong computer networks
 CSCW removes bias of single user / single computer system
Computer Supported Cooperative Work
(CSCW)
• Can no longer neglect the social aspects
• Electronic mail is most prominent success
– A metaphor of conventional mail system
– An example of asynchronous CSCW system
• CSCW systems built to support users working in groups
are referred to as groupware (Ch 19)
The World Wide Web
 Internet is simply a collection of computers linked





together.
Hypertext, as originally realized, was a closed system
Simple, universal protocols (e.g. HTTP), mark-up
languages (e.g. HTML) and global naming scheme
(URLs) made publishing and accessing easy conceive
First envisioned by Tim Berners-Lee.
First text based browser in 1991
Several graphical browsers in 1993(Mosaic)
Agent-based Interfaces
 Agent?
 People who work on someone’s behalf e.g. estate agents, travel
agents, secret agents etc.
 Software agents?
 Software which act on behalf of users within electronic world
e.g. web crawlers which search the WWW for documents that
user might find interesting, email spam filtering
 Some agents use artificial intelligence techniques to
learn, called intelligent agents.
 E.g. Eager(performs repeated actions for the user)
 Even some intelligent agents are there that don’t have a
clear embodiment
 Summing function of a Spreadsheet
Ubiquitous Computing
 Based on the idea of moving human-computer
interaction away from the desktop and out into out
everyday lives.
“The most profound technologies are those that disappear.”
Mark Weiser, 1991
 Also called pervasive computing
 Late 1980’s: computer was very apparent
 How to make it disappear?
 Shrink and embed/distribute it in the physical world
 Design interactions that don’t demand our intention
Sensor-based and Context-aware
Interaction
 Embedment of computation even deeper, but




unobtrusively, in our day-to-day life.
The user is totally unaware of the interaction taking place.
Information is gathered from sensors in Environment
Examples: Washbasin, automatic doors, lights turned on
automatically
This information can be used to modify explicit interfaces,
do things in background etc.
Sensor-based and Context-aware
Interaction
 Automatic sensing is an imperfect activity. So actions
from these ‘intelligent predictions’ should be made with
caution.
 There are two principles of appropriate intelligence
 Be right as often as possible, and useful when acting on these
predictions
 Do not cause extravagant problems in the event of an action
resulting from a wrong prediction
 The failure of must intelligent systems in past resulted
from following the first principle, but not the second.