Monday, 21 January 2013

Fundamental Principles of HCI Design

P2 Fundamental Principles of HCI Design                                                                        John Miller

The principles of HCI are Perception, Behaviour Models, Information Processing and Specialist Interfaces.

Perception: Perception is the construction, recognition and interpretation of sensory information in order to represent and understand the environment. Perception is basically how we view things. For example if you showed people an illusionary image that can appear as a young woman or an old woman, different people will perceive it differently, put simply, some will see a young woman, other will see an old woman, some may see both.

Behaviour Models: Behaviour Models predict in which way an interface or user will behave. There are two behaviour models, they are predictive models and descriptive models

Predictive Models- Predictive models are used to compare and evaluate motor behaviour in the design of interfaces and systems, for example, Keystroke Level Models (KLM), ThroughPut (TP) and Fitts Law (FL)

Explanation of- 

Keystroke Level Model is an 11-step method that can be used by individuals or companies to estimate the time it takes to complete simple data input tasks using a computer and mouse.

ThroughPut is the average rate of successful message delivery over a communication channel.

Fitts Law is a model of human movement primarily used in human–computer interaction and ergonomics that predicts that the time required to rapidly move to a target area is a function of the distance to the target and the size of the target.

Descriptive models- Descriptive models are a model of human movement primarily used in human–computer interaction and ergonomics that predicts that the time required to rapidly move to a target area is a function of the distance to the target and the size of the target.

List of descriptive models-

Key-Action Model (KAM) looks at how users interact with HCI's using keyboards and what shortcut keys HCI's use. It also looks at how the user expects the computer to react and how the computer will react.
Buxton’s three state model identifies the relative ease of using a mouse as opposed to a touchpad.
It also uses 3 stats:
Out of range - for clutching or repositioning a mouse on a mouse pad
tracking - for moving a tracking symbol such as a cursor about a display
dragging - for moving an icon on the desktop or for grouping a set of objects or a range of text

Guiard’s Model of bimanual skill-

This model was devised by Yves Guiard in 1987.
This model focuses on the roles of the hands in two hand interaction for example, preferred hand (right hand if you are right handed, left if you are left handed) does fine details where as the non-preferred hand is less accurate.

Information Processing:

Humans as a component-

The principle of human as a component is where people believe that part of a computer/HCI is the human. Because the human is a main component of a HCI, HCI's have to be designed to meet the human's needs.

Overview of human information processing-

Human information processing (HIP)is the principle in a theory that humans work like computers do.
Some people believe that the senses are input devices.
The brain and mind are the central processing unit which thinks, calculates and produces output.
The output devices are an action you perform using your body or an action you perform on a computer.
The main thing that computers don't have that humans do is common sense or intuition.


Overview of goals, operators, methods and selection (GOMS) 

The GOMS model can predict the time it will take for an action to be carried out or a command to be followed.

Goal-
Usually one high-level goal - description of what a user wants to accomplish
User tasks are split into goals which are achieved by solving sub-goals in a divide and-conquer fashion
.
Operators-

These are possible actions in the system.
There are various levels of abstraction possible for operators.

Methods-

Methods are sequences of operators that achieve a goal.

Selection rules-

Selection rules are rules that define when a user employs which method. This is need when there are a number of different methods of doing the same thing.

Example of GOMS:

Goal: Get Money from ATM

Sub Goal: use cash machine
Insert card
Enter pin
Select get cash
Enter amount
Collect Card

Collect money (Goal achieved)

Specialist Interfaces:


Design for specialist interfaces include inputs and outputs for people with different impairments, for example:

People who are visually impaired (sight problems)- would need in addition to normal computer equipment they need special electronic equipment designed to be used by people with a visual impairment. This includes purpose made portable Braille computers, Braille input and output devices for standard computers and speech activation.


People who are orally impaired (speech problems)-  People with oral impairments would prefer data input though keyboards and a mouse. They can also use certain special equipment such as a text to voice program or portable device.


People who are aurally impaired (hearing problems)- People with hearing problems would require interfaces to be visual instead of aurally.


People who are physically impaired)- People with restricted physical movement often find use of a standard keyboard may not be possible but a specially adapted device  mouse and keyboard may be more suitable.


Remote Control Devices:

Remote control devices are often used to operating televisions and DVD players wirelessly from a short line-of-sight distance.

The remote controls used in your home often use infrared (IR). The transmitter in the remote control sends out a pulse of infrared light  that represents a binary \code that is listed as a certain command such as changing the channel up 1, when a button is pressed on the remote. The receiver passes the code to a microprocessor, which decodes it and carries out the command associated with the binary code.

Specially made remote controls can be used to control many devices.

Heads Up Displays(HUD)
A heads-up display is any transparent display that presents data without requiring users to look away from their usual viewpoints, this is a widely used mechanic in gaming as well as it allows users to see information such as ammo, or a minimap without being required to for example look at away from enemies to see their ammo count.

The name comes from a pilot being able to view information with their head positioned "up" and looking forward, instead of down to look at lower instruments.

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