Chapter 12

Choosing interaction devices: hardware components

Introduction

Every user interface consists of a mixture of design componentsHardware components: also known as I/O

devices, or interaction devicesSoftware components: generated by the

underlying computer program

Choosing Interaction Devices

Interaction devices are tools used to complete a job

To choose between devices, you need to ask the right questionsQuestions are driven by constraints of the

technology and by the uses to which the technology will be put

Input Devices

Keyboards, keypads & buttons Pointing devices

Input Devices

Keyboards, keypads & buttonsDiscrete input devices: can be used to enter

individual items of informationQuestions:

What size do the keys need to be? What shape should the keyboard be? How robust does the keyboard need to be? Which keys/buttons are needed and how should

they be labeled?

Input Devices

Pointing DevicesContinuous input devices: good at tasks that

cannot be split easily into a number of discrete steps

2 types: Indirect: require the user to move a screen cursor

using a secondary device Direct: allow user to point directly at the relevant

position on the screen

Input Devices

Pointing DevicesQuestions:

How easy to learn does the device need to be? How accurate does the device need to be? How much time will the user spend on the system? How much space is there? How robust does the device need to be? How manually dexterous is the user?

Input Devices

Alternative ApproachesGesture Iris & fingerprint recognitionEyetrackingHandwriting recognitionSpeech recognition

Output Devices

Screens Loudspeakers Simple output devices

Output Devices

ScreensMost commonCan represent a wide variety of visual

elementsCRTs & LCDs

Output Devices

ScreensQuestions

How detailed does the image need to be? How many colors are needed? How large does the screen need to be? Does the screen need to be portable? How much space is there?

Output Devices

LoudspeakersQuestions

How are the speakers going to be used?

Output Devices

Simple output devicesLights, dials, gauges and buzzersQuestions

Will the data being output be better represented in analog or digital form?

Output Devices

Alternative approachesHead-up displaysHead-mounted displays (virtual reality

systems)Stereoscopic displays

Questions?