On Human Computer Interaction, HCI Dr. Saif al Zahir Electrical and - - PowerPoint PPT Presentation
On Human Computer Interaction, HCI Dr. Saif al Zahir Electrical and Computer Engineering Department UBC Human Computer Interaction HCI HCI is the study of people, computer technology, and the ways these influence each other . We study
Electrical and Computer Engineering Department UBC
the ways these influence each other. – We study HCI to determine how we can make this computer technology more usable for people.
– Engineering – Computer Science – Sociology – Cognitive psychology – Ergonomics
Numerous Applications ..
– E-commerce – Computer-aided surgery (medical applications) – Remote learning (distance education) – Computer aided Planning, Manufacturing, ... – Tourism – GIS – you name it ...
Human
recognition
attention
Computer
memory
access
memory
memory
LTM
matching
capacity
integration
system via the medium of an interface.
technologies to make working with computers easier and more productive.
more satisfied users.
constraints as well as safety-critical.
Possible Definitions
Example 1: Nuclear power plant monitoring
cause accident of catastrophic nature Example 2: Air Traffic Control
the objects, attributes, or relations that can be
mouse to invoke.
A pictorial representation of an object, an action, a property, or some other concept recognition, remembering, and discrimination
Main Objectives in User Interface Design
measure: how long a new user takes to achieve certain level of proficiency.
measure : how long an experienced user require to perform certain task with a system
measure: the number of user errors per interaction
target : computer naive users
ways to use input devices to enter information into the computer
classify the fundamental types of information entered with interaction techniques
There is no cookbook approach that ensure good interface design Why ??
experience and logical deduction from related fields such as cognitive psychology, rather than hard data
come in direct conflict with each other, and there are no algorithms for making the trade-offs
UI design is a matter of Compromise & Trade-off
Want : powerful functionality But simple and clear interface Want: ease of use But also ease of learning Want: consistency across all aspects of the interface But
Want intelligent and sophisticated interface But good performance and low cost.
We need methods to solve these conflicting requirements
– Develop a “Model” to help us understand and predict human behavior – Provide simple examples of predictions
Study them and the way they support design
Explains observed human behavior
– explain things we see people doing – help in evaluation (i.e., newly installed sys.)
Example 1: Users using keyboard shortcuts more than expected cause of high latencies in menu display Example 2: Air traffic controllers failing to trust a system because it undermined their team-oriented working style.
Empirical Laws offer simple quantitative prediction of human performance Example : Hick’s Law (1952) The time T taken to choose between a number of alternative targets is a function of the number of the targets n, and is related logarithmically :
Where k is a constant
– the correlation between size of menu and the time to make a selection – cycle times of the human brain – the time taken to move the mouse to a target
Models that predict how a whole sequence
– models which predict the sequence of actions a user will take – model which predict the level of performance if a given sequence of actions is taken by the user
Predict the speed with which the user can perform an activity
– simple dynamic model to predict the speed of
– Cycle times (can use this for the zigzag example)
perceptual 50-200 msec Average: 100 ms cognitive 25-170 msec Average: 70 ms motor 70-100 msec Average: 70 ms
Fitts Law
This Law tells us how long it will take a user to hit a target of certain diameter, W, with a pointing device that is a certain distance , A,
model.
Factors that must be considered
to the input and errors.
explained to the user
involved in the graphics package
package operates in terms of application concepts
can be displayed and how they can be manipulated.
Must be as natural as possible for the user to learn minimize memorization
structured so as to be easy to understand and remember
is easier to remember than SO
different applications, whereas function keys must be reprogrammed and relabled if they are changed
limit the number of levels
interactive dialogue and inform the user what the system is doing at each step.
different types of feedback
Example : a blinking “at work” sign to tell the user that the system is still processing Example : Mis-spelled words in Window 9x are underlined with red color
Information presented to the user
the system
Format Design to achieve greatest effectiveness
Simple and clear picture of the object or operation they represent
main components (a) main area (b) Menu area (c) Display prompts and feedback area.
to the user
window areas
expand or enlarge portion of a picture Work Area Menu
Prompts and feedback messages
your interface, less of it would be better.
Alan Cooper, Father of Visual Basic
visually
rather than the users
take control
not specific
Human Information Processing System, HIPS
Basic Components
recognition, knowledge and skills
Human Memory
– Short Term Memory, STM
Example: remembering 111-2222 vs. 359-2741
– Long Term Memory, LTM
structure (this requires reorganization constantly)
more concentration to get information from LTM)
Human Information Processor Model
Based on classic information processing model (a) set of memories and processors (b) three interacting subsystems:
Principle of operation is the recognize-act cycle
(c) properties that can be measured include:
To explain observed human behavior can provide useful insights in design lack predictive power
Simple quantitative predictions of human performance (example: Fitts law for the time taken to point to a target of a particular size).
Usability
Making systems safe, easy to learn and easy to use.
The degree to which specific users can achieve specific goals in a particular environment with efficiency, effectiveness, satisfaction.
Action is a series of progressive mental steps, resulting in a physical action.
Outcome of a physical action at the interface is mentally evaluated in a series of steps.
Stage 1- Mental Steps before physical action
deciding planning translating executing
Stage 2 - Corresponding steps after action
perceiving recognizing interpreting evaluating
7-Steps for Task Performance
– Establishing the Goals – Forming the intention – Specifying the action (Planned action sequence corresponding to intention) – Executing the action
– Perceiving the system state – Interpreting the system state (trying to make sense of it as in expectation) – Evaluating the outcome with respect to the goal and intention
Gulf of Execution and Gulf of Evaluation
Is the difference between the intention of the person and the perceived allowable action.
Is the difference between the cisible state of the system and the correct interpretation of the state of the system.
Uses of GOMS Goals, Operations, Methods, and Selection Rules
Used in:
method can be used to work out which system is fastest.
Advantages:
cheap and relatively quick to carry out. systems that don’t yet exist, but which are being designed, can be evaluated.
Business Requirement Analysis User Profile HW & SW Definition
Project Plan Business Definition
Scoping
Adding Human factors to Software Development
Application Project Team
User Interface Group
Developments in the Interface
50s - Interface with engineers at the hardware (level 1).
interface was at the hardware level.
60/70s- interface with high level programming (level 2).
software engineering and management.
70/90s Interface at the terminal (level 3).
interactivity, command languages.
80s - Interface at interaction dialogue (level 4).
GUIs, colour, sound, 3-D, animation.
90s - Interface at the work setting (level 5).
networked systems, VR.