HumanComputer Interaction

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Human-Computer Interaction

• The System

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Input
Storage
Processing
Output
The main functional elements of a computer system
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Elements of computer systemsProcessing

• Central processing unit
• speed of processing
• bus size
• instruction set
• internal architecture.

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Elements of computer systemsStorage

• Types of data storage systems
• Random Access Memory (RAM) this is the
  internal (working) memory of the system.
• External memory hard-disc drive, floppy drive,
  zip drive, CD-ROM drive etc.
• Virtual memory use of external memory
  (hard-drive) in lieu of RAM.

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Elements of computer systemsData Input

• Main types of data input systems
• Text input.
• Pointing devices.
• Digitizer tablets.
• Real media input.
• Body sensors.
• Data Input.

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Elements of computer systemsOutput

• Main types of output systems
• Visual display systems.
• Audible outputs.
• Printing.
• Mechanical outputs.
• Data output.

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A cognitive science perspective
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Types of KR

• Propositional representation
• For concepts, events etc
• Analogical representation
• For shapes, pictures etc
• Procedural representation
• For doing things etc

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Knowledge Representation

• Semantic episodic knowledge
• Semantic knowledge represents
• vocabulary items i.e. dictionary knowledge e.g.
  word meaning and
• descriptive items i.e. encyclopaedic knowledge
  e.g. facts and relationships.
• Episodic knowledge represents event like items
  i.e. experiential information

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Semantic Networks

• Used to represent semantic knowledge
• In its simplest form, a semantic network is a
  hierarchical class structure
• It is constructed of nodes, representing concepts
  etc, and links, representing relations etc.
• Attributes may be inherited from parent classes
• Knowledge organization by association linking
  different domains of knowledge

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Table
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SurfaceTop
Table
has
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SurfaceTop
Table
has
has
Legs
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Furniture
Is-a
SurfaceTop
Table
has
has
Legs
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Furniture
Is-a
SurfaceTop
Table
has
Used for
playing
has
working
Legs
dining
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animal
human
bird
fish
canary
salmon
man
woman
classroom
john
sue
table
shark
ostrich
books
computer
paper
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Other KR Structures

• Structured representation Scripts
• Proposed by Schank (Cognitive/computer science)
• Structured representation Frames
• Proposed by Minsky (Cognitive/computer science)

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Table Is a Has a Supported by Used
for Used for . . .
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Table Is a Has a top Supported by Used
for Used for . . .
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Table Is a Has a top Supported by Used
for Used for . . .
Item of furniture
Squared or rect., made of wood
Legs, usually made of wood
Dining, working, playing etc.
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Lecture Frame
Subject
Room Location
Range
Default
Start time
Range
Duration
Range
Default
Finish time
Rule (start time duration)
Equipment
Range
Default
Lecturer
Rule (consult lecture schedule given room
location start time)
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Frames

• Are a special type of schems, with variable slots
  whose fillers identify an instantiated frame.
• Similar to schemas, they can be organized in a
  number of different levels.
• However, unlike schemsa, they do not possess
  active processors
• They are widely used in knowledge bases
• They have also been used in task analysis

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Park Frame


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Scripts

• A script is a special type of schema used for
  frequently occurring events
• Similar to schemas, they have variables roles
  (persons) and props (objects).
• They also have
• Entry conditions for activating a script
• Scenes a particular grouping of activities

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Lecture Script Props Lecture room, whiteboard,
markers, overhead projector, data projector,
computer, tables, chairs Roles student, lecturer
Point of view lecturer Event sequence 1-
enter room 2- set up unless attendance 0 when
exit room 3- deliver lecture 4- pack up 5-
Exit room
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Restaurant Script Props tables, chairs,
waiter/waitress, till Roles customer,
waiter/waitress Point of view customer Entry
conditions hungry, socialising, has money Event
sequence 1- enter restaurant 2- be seated by
waiter 3- examine menu 4- order food 5- wait
for food 6- food served by waiter 7- eat
food Exit conditions food consumed, tip paid,
bill paid
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Knowledge Acquisition

• Cognitive Stage
• Associative Stage
• Autonomous Stage

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Recall and Recognition

• Recall is the act of remembering something that
  has been memorized in the past e.g. your ID and
  Password for logging into your system.
• Recognition is the act of recognizing an item
  when presented to you it means bring back to
  cognition.
• Recognition is an easier cognitive task than
  recall it is why menus are preferred to script
  commands.

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Input / Output Systems
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Elements of computer systemsData Input

• Main types of data input systems
• Text input.
• Pointing devices.
• Digitizer tablets.
• Real media input.
• Body sensors.
• Data Input.

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Text Input

• Mainly used for entering coded text e.g. ASCII
  code.
• Keyboards, for direct keying of code
• Qwerty.
• Chord.
• Dvorak.

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QWERTY arrangement not optimal for typing
layout due to typewriters.
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Dvorak common letters under dominant fingers
biased towards right hand common combinations
of letters alternate between hands 10-15
improvement in speed and reduction in fatigue
But - large social base of QWERTY typists produce
market pressures not to change
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Chord keyboards only a few keys - four or 5
letters typed as combination of keypresses
compact size - ideal for portable applications
short learning time - keypreses reflect shape of
desired letter fast But - social resistance,
plus fatigue after extended use
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• Other methods for text input
• Speech recognition use of speech recognition
  tools to convert real media (speech) into coded
  text.
• Handwriting recognition use of HWR tools to
  convert handwriting signals (from digitizer
  tablets) into coded text.

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Pointing devices

• Mainly used with GUI systems (Graphical User
  Interface).
• Arrow Keys (on keyboard).
• Mouse
• Mechanical.
• Optical.
• Tracker Ball.
• Joy Stick.
• Digitized surfaces
• touch pad
• touch screen
• digitizer tablet
• Light Pen.

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Digitizing Surfaces

• Mainly used with hand-related media e.g.
  handwriting, free hand drawing, CAD drawing etc.
  or for pointing actions.
• Digitizer tablets a board based transducer
  driven by a corded or cordless pens.
• Touch screen a transparent transducer, usually
  placed on top of CRT or LCD display unit. The
  LCD option is becoming more popular in PDAs and
  Tablet PCs, as an electronic note-pad.
• Touch Pad mostly used in mobile computing
  (notebooks).

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Real media input 1

• Used for the acquisition of audio, video and
  print media..
• Audio cards connects to an audio source e.g.
  microphone or line input. It then applies
  analogue-to-digital conversion followed by some
  suitable encoding process e.g. ADPCM, to feed the
  computer system with the corresponding data
  stream.
• Video capturing cards also connects to video
  sources e.g. video cam, VCR. It then applies A/D
  conversion followed by some suitable encoding
  process e.g. MPEGII, to generate the data stream.

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Real media input 2

• Used for the acquisition of audio, video and
  print media..
• Digital video more recently, digital video
  sources are becoming available, e.g. video cam
  etc., which directly generates suitable data
  streams.
• Print media is usually acquired through scanners.
  Optical scanning is the basis of optical
  processing of documents, which uses character
  recognition technology to convert scanned
  content, usually in GIF or TIF graphic format to
  encoded text e.g. ASCII.

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Data input

• This area addresses machine to machine
  communication, where data is usually received
  through data ports for processing, storage ..
  etc.
• Types of data ports usually available on
  computers include
• parallel communication ports e.g. for printing
  etc.
• serial communication ports, e.g. for modems,
  network interfacing etc.
• universal synchronous ports (USB) for any of the
  above.
• Infra-red communication ports, e.g. for
  communication with mobile phones etc.

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Elements of computer systemsOutput

• Main types of output systems
• Visual display systems.
• Audible outputs.
• Printing.
• Mechanical outputs.
• Data output.

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Visual display systems

• This is the most widely used form of output.
• Its early use was in the form of VDUs (visual
  display units). These are CRT based monitors,
  that uses raster scan, for the display of text
  output.
• Graphical User Interfaces (GUIs) was later
  developed, which became the basis of the WIMP
  system (windows, icons, menus and pointers).
• Vector display monitors, based on CRT, are also
  available, but used mainly for CAD systems etc.
• More recently, LCD systems are now growing out of
  the mobile computing sector to replace the
  desk-top display units.

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Audible outputs

• With the developing media capability of machines,
  audible outputs are now becoming a norm.
• Types of audible outputs include
• speech, in text-to-speech synthesis systems.
• Earcons, which are short audible codes used to
  alert the user e.g. when it is not possible to
  successfully complete an operation, or to confirm
  some completed action.
• Compound sounds, e.g. MIDI output.

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Printing

• This is the oldest method of human-computer
  communication, even before VDUs came into use.
  Early computers used to receive instructions
  through punched cards and tapes and produce
  responses by printing them on paper.
• After VDUs and keyboards became the primary
  communication interface with computers (computer
  workstations), printing was confined to the
  production of hardcopy output e.g. letters,
  reports, receipts, books etc.

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Mechanical output

• Used for the mechanical manipulation of physical
  objects. There are two categories of mechanical
  outputs
• as an interface to the tactile and haptic
  perceptions of human users e.g. in virtual
  reality environments etc.
• for the production of mechanical force, e.g.
  activation of solenoids, electric motors,
  hydraulic manipulators etc. This category is
  widely used in industrial applications, including
  robotic control etc.

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Data output

• This area addresses machine to machine
  communication, where data is usually sent to
  other machines through data ports for processing,
  storage .. etc.
• Types of data ports usually available on
  computers include
• parallel communication ports e.g. for external
  storage etc.
• serial communication ports, e.g. for modems,
  network interfacing etc.
• universal synchronous ports (USB) for any of the
  above.
• Infra-red communication ports, e.g. for
  communication with mobile phones etc.