Course: Human-Computer Interaction

Course Code: AID283(SY – Btech. –AIDS/CSD )

UNIT I
 Subject Details

• Teaching Scheme:
• Theory: 03 Hrs / week
• Credits: 3-0-0
• Mid Semester Examination-I: 15 Marks
• Mid Semester Examination-II: 15 Marks
• Continuous In-semester Evaluation: 10 Marks
• Teacher Assessment: 10 Marks
• End Semester Examination: 50 Marks
• End Semester Examination (Duration): 02 Hrs
 Unit I

Introduction
• The Human
• The Computer
• The interaction
• Paradigms,
• Guidelines
• Principles, and Theories
• Importance of good design
• Examples: Identifying good vs bad design
 The Human
• Humans are limited in their capacity to process information
• Information is received and responses given via several input and output channels:
• visual channel
• auditory channel
• haptic channel
• movement

• Information is stored in memory:

• sensory memory
• short-term (working) memory
• long-term memory

• Information is processed and applied:

• reasoning
• problem-solving
• skill acquisition
• error

• Emotion influences human capabilities.

• Users share common capabilities but are individuals with differences, which should not
 Types of Senses and Interpretation in Human

• Vision
• Reading
• Hearing
• Touch
• Movement
• Memory
• Short-term memory (STM)
• Long-term memory (LTM)
Vision Interpreting the signal Reading

 Two stages in vision  Size and depth :visual angle indicates how  Several stages:visual
 • physical reception of much of view object occupies.(relates to size pattern perceived decoded
stimulus and distance from eye) using internal
 • processing and  visual acuity is ability to perceive detail representation of
interpretation of stimulus (limited)familiar objects perceived as constant language.
size (in spite of changes in visual angle  interpreted using
 The Eye - physical when far away) knowledge of syntax,
reception:  cues like overlapping help perception of size semantics, pragmatics
 mechanism for receiving and depth
light and transforming it  The visual system compensates for:  Reading involves saccades
into electrical energy Movement and changes in luminance. and fixations
 light reflects from objects  Context is used to resolve ambiguity  Perception occurs during
 images are focused fixations
upside-down on retina.  Optical illusions sometimes occur due to over  Word shape is important to
 retina contains rods for compensation recognition
low light vision and cones  Negative contrast
for colour vision improves reading from
 ganglion cells (brain!) computer screen
detect pattern and
movement
Hearing Touch (Haptic) Movement
 Provides information  Provides important  Time taken to respond to stimulus:
about the environment: feedback about reaction time + movement time
distances, environment.  Movement time dependent on age, fitness etc.
directions, objects, etc.  May be key sense for  Reaction time - dependent on stimulus type:
someone who is  visual~ 200ms, auditory~ 150 ms, pain~ 700ms
 Physical apparatus: visually impaired.  Increasing reaction time decreases accuracy in the
 The outer ear protects  Stimulus received via unskilled operator but not in the skilled operator.
the inner and amplifies receptors in the skin:  Fitts' Law describes the time taken to hit a screen
sound  thermoreceptors – target. Fitts law is useful for web designers when
 middle ear transmits heat and cold deciding where to place the next button
sound waves as  nociceptors –  Mt = a + b log2(D/S + 1)
vibrations to the inner ear pain  where: a and b are empirically determined
 Inner ear –  mechanoreceptors constants
chemical transmitters are – pressure  Mt is movement time
released  D is Distance
(some instant, some  S is Size of target
and cause impulses in the continuous)  targets as large as possible
auditory nerve  Some areas more distances as small as possible
 Sound sensitive than others
 pitch – sound e.g. fingers.
frequency  Kinethesis - awareness
 loudness – of body position affects
amplitude comfort and
 timbre – type or performance.
quality
Memory Short-term memory Long-term memory (LTM)
(STM)
 There are three  Scratch-pad for  Repository for all our knowledge
types of memory temporary recall  slow access ~ 1/10 second
function:  slow decay, if any
 rapid access ~  huge or unlimited capacity
Sensory memories 70ms
  Two types
 Short-term memory  rapid decay ~  episodic – serial memory of events
or working memory 200ms  semantic – structured memory of facts,concepts, skills
Comes from
attention  limited capacity -  semantic LTM derived from episodic LTM
 Long-term memory 7± 2 chunks  Semantic memory structure
relates to Rehearsal  provides access to information
 Selection of stimuli  represents relationships between bits of information
governed by the  supports inference
level of arousal.  Model: semantic network
 inheritance – child nodes inherit properties of parent nodes
 relationships between bits of information explicit
 supports inference through inheritance
 Model of Human Memory

Three main types of memory are processed in the brain: Sensory Memories, Short-term Memories, Long-term Memories

Sensory Memories Short-Term Memories Long-Term Memories

Sensory memories are the Short-term memory is used to process sensory In most instances the memories
memories which are stored for memories which are of interest to us – for transferred to our short-term memories
tiny time periods and which whatever reason. The sensory memory is are quickly forgotten. This is, probably, a
originate from our sensory transferred to the short-term memory where it good thing. If we didn’t forget the huge
organs (such as our eyes or our may be processed for up to a minute (though if volumes of information that we perceive
nose). They are typically retained the memory is rehearsed – e.g. repeated – it on a daily basis we could well become
for less than 500 milliseconds. may remain in short-term memory for a longer overloaded with information and find
period up to a few hours in length). processing it in a meaningful way soon
Visual sensory memory is often became impossible.
known as iconic memory. Short-term memory is of limited capacity.
Sensory visual memories are the Experiments conducted by, among others, In order for most memories to transfer
raw information that the brain George A Miller the psychologist, and reported from short-term to long-term memory –
receives (via the optic nerve) in his paper “The Magical Number Seven, plus or conscious effort must be made to effect
from the eye. We store and minus two” suggest that we can store between 5 the transfer. This is why students review
process sensory memories and 9 similar items in short-term memory at the for examinations; the repeated
automatically – that is without most. application of information or rehearsing
any conscious effort to do so. This capacity can be increased by a process of information enables the transfer of the
known as “chunking”. This is where we group material they are studying to long-term
items to form larger items. memory.
Explicit memory :- It is the conscious, intentional recollection
of factual information, previous experiences, and concepts.
Explicit memory can be divided into two categories: episodic
memory, which stores specific personal experiences,
and semantic memory, which stores factual information.
Implicit memory:- This refers to unconscious memories such
as skills, e.g: how to get dressed, eat, drive, ride a bicycle, etc.
Without having to re-learn the skill each time. With the help of
our memory, we can store, retain, and remember at our ease at
record notice most of the things in our life and can thus make
things a our life.
 The Computer
• A computer system comprises various elements, each of which affects
the user of the system.
• Paper output and input: the paperless office and the less-paper
• Input devices for interactive use, allowing text entry, drawing, and office:
selection from the screen:
• different types of printers and their characteristics,
• Text entry: traditional keyboard, phone text entry, speech and character styles and fonts
handwriting
• Pointing: principally the mouse, but also the touchpad, stylus, and
• scanners and optical character recognition
others • Memory:
• 3D interaction devices • short-term memory: RAM
• Output display devices for interactive use: • long-term memory: magnetic and optical disks
• different types of screens mostly using some form of bitmap • capacity limitations related to document and video storage
display
• access methods as they limit or help the user
• large displays and situated displays for shared and public use
• digital paper may be usable shortly.
• Processing:

• Virtual reality systems and 3D visualization have special interaction • the effects when systems run too slow or too fast, the
myth of the infinitely fast machine
and display devices.
• Various devices in the physical world: • limitations on processing speed

• physical controls and dedicated displays • networks and their impact on system performance.

• sound, smell, and haptic feedback

• sensors for nearly everything including movement, temperature,
 Elements of computer Systems
a computer system is made up of various elements

each of these elements affects the interaction

• input devices – text entry and pointing
• output devices – screen (small&large), digital paper
• virtual reality – special interaction and display devices
• physical interaction – e.g. sound, haptic, bio-sensing
• paper – as output (print) and input (scan)
• memory – RAM & permanent media, capacity & access
• processing – speed of processing, networks
input devices – 1. layout – QWERTY
keyboards • Standardised layout Chord keyboards:
• non-alphanumeric keys are
 only a few keys - four or 5
placed differently
• Most common  letters typed as a combination of
text input device • accented symbols needed for keypresses,compact size, ideal for portable
different scripts applications
• Allows rapid
entry of text by • minor differences between
 short learning time
experienced users UK and USA keyboards
 fast – once you have trainedBUT social
• Keypress closes • QWERTY arrangement not resistance, plus fatigue after extended use
the connection, optimal for typing
phone pad and T9 entry:
causing a • alternative keyboard layouts
character code to  use numeric keys with
be sent • Alphabetic multiple presses

• Usually • keys arranged in alphabetic  surprisingly fast!

order
connected by  T9 predictive entry
cable, but can be • not faster for trained typists  type as if single key for each letter
wireless
• not faster for beginners either!  use dictionary to ‘guess’ the right word
•
Chord keyboards phone pad and T9 entry Handwriting recognition
 only a few keys - four or 5  use numeric keys with  Text can be input into the computer,
 letters typed as a multiple presses using a pen and a digesting tablet
combination of keypresses  surprisingly fast!  natural interaction
 compact size  T9 predictive entry  Technical problems:
 – ideal for portable  type as if single key for each letter  capturing all useful information -
applications  use dictionary to ‘guess’ the right stroke path, pressure, etc. in a
 short learning time word natural manner
– keypresses reflect letter  segmenting joined up writing into
shape individual letters.
 fast – once you have  interpreting individual letters
trained  coping with different styles of
 BUT - social resistance, plus handwriting
fatigue after extended use  Used in PDAs, and tablet computers
…
 NEW – niche market for … leave the keyboard on the desk!
some wearables
 positioning, pointing and drawing – The Mouse
• Devices used:mouse, touchpad trackballs, joysticks ,touch screens, tablets eyegaze, cursors
the Mouse Touchpad Joystick and keyboard nipple

Handheld pointing device: very common  small touch  Joystick

easy to use sensitive tablets  Indirect pressure of stick = velocity of
Two characteristics:planar movement Buttons ‘stroke’ to move movement
Mouse located on desktop:requires physical space, mouse pointer  buttons for selection on top or on front like a
no arm fatigue.Relative movement only is  used mainly in trigger
laptop  often used for computer games aircraft
detectable. computers controls and 3D navigation
Movement of mouse moves screen cursor  good  Keyboard nipple
Screen cursor oriented in (x, y) plane, ‘acceleration’  for laptop computers
mouse movement in (x, z) plane … settings  miniature joystick in the middle of the keyboard
important  Stylus and light pen
Two methods for detecting motion  fast stroke
 lots of pixels per  Stylus:small pen-like pointer to draw directly on
Mechanical:Ball on underside of mouse turns as inch moved screen
mouse is moved Rotates orthogonal. Potentiometers  initial movement  may use touch sensitive surface or magnetic
to the target detection, used in PDA, tablets PCs and drawing
Can be used on almost any flat surface  slow stroke tables
 less pixels per  Light Pen: now rarely used
Optical: light emitting diode on underside of mouse inch  uses light from screen to detect location
may use special grid-like pad or just on desk less  for accurate
susceptible to dust and dirt detects fluctuating positioning
alterations in reflected light intensity to calculate
relative motion in (x, z) plane
Touch-sensitive screen Eyegaze Cursor keys
Detect the presence of finger or  control interface by eye gaze direction  Four keys (up, down, left, right) on
stylus on the screen.  e.g. look at a menu item to select it keyboard.
works by interrupting matrix of  uses laser beam reflected off retina  Very, very cheap, but slow.
light beams, capacitance  … a very low power laser!  Useful for not much more than basic
changes or ultrasonic  mainly used for evaluation (ch x) motion for text-editing tasks.
reflections  potential for hands-free control  No standardised layout, but inverted
direct pointing device  high accuracy requires headset “T”, most common
 cheaper and lower accuracy devices
Advantages: available
fast, and requires no sit under the screen like a
specialised pointer small webcam
good for menu selection
suitable for use in hostile
environment: clean and safe
from damage.
Disadvantages:
finger can mark screen
imprecise (finger is a fairly
blunt instrument!)
difficult to select small
regions or perform
accurate drawing
lifting arm can be tiring
 display devices
bitmap screens (CRT & LCD) Cathode ray tube Liquid crystal displays

screen is vast number of coloured dots  Stream of electrons emitted from  Smaller, lighter, and … no radiation
resolution and colour depth: electron gun, focused and directed problems.
Resolution used (inconsistently) for by magnetic fields, hit phosphor-
number of pixels on screen (width x coated screen which glows  Found on PDAs, portables and
height)  used in TVs and computer monitors notebooks,
Health hazards of CRT !: … and increasingly on
density of pixels (in pixels or dots per X-rays: largely absorbed by screen (but desktop and even for home TV
inch - dpi) not at rear!)
typically between 72 and 96 dpi UV- and IR-radiation from phosphors:  also used in dedicted displays:
Aspect ratio insignificant levels: Radio frequency digital watches, mobile
ration between width and height emissions, plus ultrasound (~16kHz) phones, HiFi controls
4:3 for most screens, 16:9 for wide- Electrostatic field - leaks out through
screen TV tube to user.  How it works …
Colour depth: Electromagnetic fields (50Hz-0.5MHz).  Top plate transparent and polarised,
how many different colours for each Create induction currents in conductive bottom plate reflecting.
materials, including the human body.  Light passes through top plate and
pixel? black/white or greys only crystal, and reflects back to eye.
256 from a pallete  Voltage applied to crystal changes
8 bits each for red/green/blue = polarisation and hence colour
millions of colours  N.B. light reflected not emitted => less
eye strain
 display devices
large displays situated displays Digital paper

 used for meetings, lectures, etc. 


displays in ‘public’ places
large or small
 what?
 technology  thin flexible sheets
plasma – usually wide screen  very public or for small group

 display only  updated electronically
 video walls – lots of small screens  but retain display
together  for information relevant to location
 or interactive  how?
 projected– RGB lights or LCD  use stylus, touch sensitive screem
projector  in all cases … the location matters  small spheres turned
 hand/body obscures screen  meaning of information or interaction  or channels with coloured
 may be solved by 2 projectors + is related to the location liquid
clever software and contrasting spheres
 back-projected  rapidly developing area
 frosted glass + projector behind
virtual reality – special interaction physical interaction – e.g. sound, paper – as output (print) and input (scan)
and display devices haptic, bio-sensing

 positioning in 3D space:  beeps, bongs, clonks, whistles and  Printing:

 cockpit and virtual controls whirrs image made from small dots allows any
 steering wheels, knobs and dials …  used for error indications character set or graphic to be printed,
just like real!  confirmation of actions e.g. keyclick critical features:
Resolution: size and spacing of the dots
 the 3D mouse Touch, feel, smell: measured in dots per inch (dpi)
 six-degrees of movement: x, y, z + touch and feeling important in games … Speed usually measured in pages per
roll, pitch, yaw vibration, force feedback in simulation … minute
 data glove feel of surgical instruments called haptic Types of dot-based printers
 fibre optics used to detect finger devices. dot-matrix printers: use inked ribbon (like
position texture, smell, taste: current a typewriter line of pins that can strike the
 VR helmets ribbon, dotting the paper.
technology very limited ink-jet and bubble-jet printers: tiny blobs
 detect head motion and possibly
eye gaze of ink sent from print head to paper
Environment and bio-sensing: sensors laser printer: like photocopier: dots of
 whole body tracking all around us car courtesy light – small electrostatic charge deposited on drum,
 accelerometers strapped to limbs switch on door, ultrasound detectors – which picks up toner (black powder form of
or reflective dots and video security, washbasins,RFID security tags ink) rolled onto paper which is then fixed
processing in shops: temperature, weight, location with heat
… and even our own bodies: iris
scanners, body temperature, heart rate,
galvanic skin response, blink rate
 Memory of Computer
Short-term Memory - RAM processing – speed of processing, networks

Random access memory (RAM)  Moore’s law: computers get faster and faster!
on silicon chips, 100 nano-second access time  1965 …Gordon Moore, co-founder of Intel, noticed a pattern
usually volatile (lose information if power turned off) processor speed doubles every 18 months
data transferred at around 100 Mbytes/sec similar pattern for memory: but doubles every 12 months!!
Some non-volatile RAM used to store basic set-up information
Typical desktop computers: 64 to 256 Mbytes RAM Networked computing:
Long-term Memory – disks: Networks allow access to …large memory and processing
other people (groupware, email)
magnetic disks shared resources – esp. the web
floppy disks store around 1.4 Mbytes Issues: network delays – slow feedback, conflicts - many
hard disks typically 40 Gbytes to 100s of Gbytes people update data unpredictability
access time ~10ms, transfer rate 100kbytes/s
The internet:
optical disks history …1969: DARPANET US DoD,
use lasers to read and sometimes write common language (protocols):
more robust that magnetic media TCP – Transmission Control protocol
CD-ROM lower level, packets (like letters) between machines
- same technology as home audio, ~ 600 IP – Internet Protocol
Gbytes reliable channel (like phone call) between programs on machines
email, HTTP, all build on top of these
DVD - for AV applications, or very large files
 Interaction
• Interaction models help us to understand the interaction between the user and the system.
• They address the translations between user wants and the system does.
• Ergonomics looks at the physical characteristics of the interaction.
• The interaction takes place with an organizational perspective that affects both the user and the system.
• What is interaction?

• Three Types of Computing Environments :

• • Physical Computing Environment
• • Social Computing Environment
• • Cognitive Computing Environment
Physical Computing Social Computing Environment Cognitive Computing Environment
Environment

– Safety – way people use computers. –– – Age

– Efficiency Different computing paradigms imply – Disabilities
– User Space different social environments. • For – Degree of technical knowledge
– Work Space instance, personal computing is usually a – Degree of focus
– Lighting Noise solitary activity done in an office or an – Cognitive Stress.
– Pollution. isolated corner of the house. Mobile
computing is often done outside and in
public places

Analyzing Interaction Paradigms: ( 5W + H)

 (The ―who, what, where, why, and how )

 (5W+H) heuristic is a procedure that can be used to define and analyze existing interaction paradigms
 And explore the elements and objects with which the user interacts.
  The What/How: This is used to understand the physical and virtual interface components. For example, I/O devices,
windows, icons, etc. 
 Where/When: This is related to the physical environment. It looks at the differences between office, portable, and wearable
systems.
  Who/Why: This looks at the types of tasks and skill sets required.
 models of interaction:
terms of interaction Donald Norman model interaction framework

 Seven stages  Abowd and Beale framework

 domain – the area of work under  The user establishes the goal
study  formulates intention
 e.g. graphic design  specifies actions at the interface
 executes action
 goal – what you want to achieve  perceives system state
e.g. create a solid red triangle  interprets system state
 task– how you go about doing it  Evaluate system state concerning goal
– ultimately in terms of  Norman’s model concentrates on the
operations or actions user’s view of the interface  extension of Norman…
e.g. … select the fill tool, click over the  execution/evaluation loop:  their interaction framework has 4 parts
triangle  user
 input
 system
 output
 user establishes the goal
 formulates intention  each has its unique
 specifies actions at interface language:interaction means translation
 executes action between languages
 perceives system state
 interprets system state  problems in interaction = problems in
 evaluates system state with respect to translation
goal
 Styles of Interaction
There are a number of common interface styles including:

command line interface: It provides a means of expressing instructions to the computer directly,using function keys, single
characters, abbreviations or whole-word commands

menus: the set of options available to the user is displayed on the screen, and selected using the mouse, or numeric or
alphabetic keys

natural language: user cant remember a command so instructions are expressed in everyday words! Natural language
understanding, both of speech and written input.

question/answer and query dialog:Question and answer dialog is a simple mechanism for providing input to an application
in a specific domain. The user is asked a series of questions.
form-fills and spreadsheets:Form-filling interfaces are used primarily for data entry but can also be useful in data retrieval
applications.

WIMP: WIMP interface style, often simply called windowing systems. WIMP stands for windows, icons, menus and pointers

point and click: It clearly overlaps in the use of button

three-dimensional interfaces :There is an increasing use of three-dimensional effects in user interfaces. The most
obvious example is virtual reality, but VR is only part of a range of 3D techniques available to the interface designer.
 Paradigms : Means pattern or model
What are Paradigms of Interaction: New computing technologies arrive, creating a new perception of the
human—computer relationship. We can trace some of these shifts in the history of interactive technologies.

Example Paradigm Shifts:

 Batch processing: Impersonal computing

 Timesharing: Interactive computing

 Networking: Community computing

 Graphical display: Direct manipulation

 Microprocessor: Personal computing

 WWW: Global information

 Ubiquitous Computing:A symbiosis of physical and electronic worlds in service of everyday activities.
 PARADIGMS FOR INTERACTION
1. Time sharing : 2. Video display units: (VDU) 3. Programming toolkits

• truly interactive exchange between 1. Using VDU like Sketchpad it was Programming toolkitprovides all tools to
programmer and computer was possible to change something in the programmers on developing the set of
possible. computer’s memory. programming tools
• The computer could now project
itself as a dedicated partner with It was a kind of simulation language that They require these tools in order to build
each individual user enabled computers to to ineract more complex interactive systems.
• the advent of time sharing, real graphically.
human–computer interaction was
now possible.

4. Personal computing: 5. Window systems and the WIMP

interface:
1970s of the ultimate handheld personal The window is the common mechanism
computer Dynabook technology we associated with these physically and
have available today. logically separate display spaces.

Interaction based on windows, icons,

menus and pointers was commercial
in April 1981
 ERGONOMICS:
Ergonomics (or human factors) is traditionally the study of the physical characteristics of the interaction: how the controls are
designed, the physical environment in which the interaction takes place, and the layout and physical qualities of the screen.
1. Arrangement of controls and 3. Health issues 4. The use of color:
displays: Colors used in the display
Again these are factors in the
functional controls and displays are physical environment that directly affect 1.. Blue should not be used to display
organized so that those that are the quality of the interaction and the critical information.
functionally related are placed together. user’s performance:
sequential controls and displays are 2. The colors used should also correspond
organized to reflect the order of their Physical position As we noted in the to common conventions and user
use in a typical previous section, users should be able to expectations.
frequency controls and displays are reach all controls comfortably and see Red, green and yellow are colors
organized according to how frequently all displays. frequently associated with stop, go and
they are used. Temperature : User performance standby respectively.
weakens at high or low temperatures,
2. The physical environment of the with users being unable to concentrate Therefore,
interaction: efficiently.
The following terms are taken care in Lighting The lighting level will again red may be used to indicate emergency
this factor: depend on the work environment. Noise and alarms;
Where will the system be used? By Excessive noise can be harmful to green, normal activity
whom will it be used? Will users be health,. Yellow : standby and auxiliary function.
sitting, standing Time The time users spend using the
or moving about? system should also be controlled.
 Guidelines in Human Computer Interface(HCI)
Important Guidelines in HCI: 1. Shneiderman’s Eight Golden Rules 2.Norman’s Seven Principles 3. Heuristic Evaluation
4. Nielsen’s Ten Heuristic Principles 5.Interface Design Guidelines for Every Component 6.Guidelines for Error Prevention and
Handling 7.Performance Optimization 8.Visual Design Security and Privacy Testing

Shneiderman’s Eight Golden Rules: Norman’s Seven Principles

Norman’s Seven Principles are a set of seven guidelines for
Strive for consistency: Use consistent terminology, fonts, and designing user interfaces that are easy to use. The principles
design elements throughout the interface. are:
Cater to universal usability: Design the interface to be Usefulness: The interface should be useful for the tasks that
accessible to users with a wide range of abilities. users need to complete.
Offer informative feedback: Provide users with feedback on Usability: The interface should be easy to learn and use.
their actions so that they know what is happening. Desirability: The interface should be aesthetically pleasing and
Design dialogs to yield closure: Make sure that users know motivating to use.
when a dialog box is complete and what they need to do to Findability: Users should be able to easily find the information
proceed. and features that they need.
Prevent errors: Design the interface to prevent errors from Accessibility: The interface should be accessible to users with
happening in the first place. a wide range of abilities.
Permit easy reversal of actions: Allow users to easily undo Credibility: The interface should be trustworthy and credible.
their mistakes. Value: The interface should provide users with value that is
Support internal locus of control: Make users feel like they worth the time and effort it takes to use it.
are in control of the system.
Reduce short-term memory load: Minimize the amount of
information that users need to keep in their heads in order to
use the system.
 Guidelines in Human Computer Interface(HCI)

Nielsen’s Ten Heuristic Principles Here are some specific guidelines for common interface
components:
Visibility of system status: Keep users informed about Buttons: Use clear and concise labels, and make sure that buttons
what is happening. are large enough to be easily clicked or tapped.
Match between system and the real world: Use words, Input fields: Provide clear instructions and validation, and make
phrases, and concepts that are familiar to the user, sure that input fields are large enough to accommodate the
User control and freedom: Allow users to easily recover expected input.
from errors and undo actions. Checkboxes and radio buttons: Use clear and concise labels, and
Consistency and standards: Use consistent terminology group related checkboxes and radio buttons together.
and conventions throughout the system. Menus: Organize menu items logically, and use clear and concise
Error prevention: Even better than good error messages labels.
Recognition rather than recall: The user should not have Tooltips: Use tooltips to provide additional information about
to remember information from one part of the dialogue to interface elements, but avoid using them to provide essential
another. instructions.
Flexibility and efficiency of use: speed up the interaction Dialog boxes: Use clear and concise language, and make sure that
for the experienced user such as by allowing shortcuts with dialog boxes are easy to understand and complete.
non-textual navigation modes.
Aesthetic and minimalist design: Dialogues should not
contain information which is irrelevant or rarely needed.
Help users recognize, diagnose, and recover from
errors: Error messages should be expressed in plain
language (no codes
Help and documentation: it may be necessary to provide
help and documentation..
 Guidelines in Human Computer Interface(HCI)

guidelines for error prevention and Performance Optimization Visual Design

handling: guidelines for performance Here are some guidelines for visual design:
Prevent errors from happening in the optimization: Use a consistent design language: This
first place: This can be done by Use appropriate data types and will help to create a unified and cohesive
providing clear instructions, validation, algorithms: This will help to improve look and feel for your application.
and feedback. the performance of your application. Use appropriate colors and fonts: Make
When errors do occur, provide clear Cache frequently accessed data: This sure that your colors and fonts are easy to
and concise error messages: Explain will reduce the amount of time it takes read and understand.
the problem in plain language, and to load data from the database. Use white space effectively: White space
suggest a solution. Optimize your database queries: This can be used to improve the readability and
Make it easy for users to recover from will help to improve the performance of usability of your interface.
errors: Allow users to easily undo their your database. Use images and icons sparingly: Images
actions, and provide a way for them to Use a content delivery network and icons can be used to add visual
get help if needed. (CDN): This will help to improve the interest to your interface, but avoid using
performance of your application by them too much, as this can make your
serving static content from servers that interface look cluttered and
are located close to your users overwhelming.
 Importance of Good Design
• Importance of HCI:
• Effects of a bad screen design are:
• People will have greater difficulty in doing their job
• More prone to mistakes
• Chase people away from the system
• Lead to aggravation, frustration and stress
• Benefits of a good design are:
• Screens are less crowded
• Would be less time-consuming, 25 percent less time
• Screen would be 20 percent more productive
• 25 percent fewer errors
• Improve decision-making time
• Training cost are lower
• The organization customers benefit because of improved services
 Good Vs Bad Design
points Good Design Bad Design

Change in one part of the system does not always One conceptual change requires changes
Change
require a change in another part of the system. to many parts of the system.

Logic Every piece of logic has one and only one home. Logic has to be duplicated.

Nature Simple Complex

Cost Small Very high

Link The logic link can easily be found. The logic link cannot be remembered.

System can be extended with changes in only one

Extension System cannot be extended so easily.
place.
 Important Questions:

• 1. Explain Paradigms of Interaction in HCI.

• 2. Explain in detail about different types of memory, storage formats and methods of access.
• 3. What is short-term memory?
• 4. Describe Gestalt theory and Problem space theory.
• What are Norman’s seven principles of Making complex tasks simple?
• 5. What is HCI? Who is involved in HCI?
• 6. What is Schneiderman’s 8 Golden Rule of Design?
• 7. What are the common Interaction styles?
• 8. Explain in Detail about Human Memory Systems.
• 9. Explain in Detail about display devices.
• 10. Explain the Importance of HCI and explain Good vs Bad Design.
• 11. Give examples of deductive, inductive, and abductive reasoning in very short.
• 12. What is Ubiquitous Computing?

Submitted by : Mrs A. R. Kothimbire

Department of Emerging Science and Technology MIT Abad