Interface Design Workshop Shad Valley Waterloo, 2003 (Day 2 of 4) Presenter: Danny Ho Advanced Interface Design Lab University of Waterloo

Today’s Topics Cognitive Ergonomics –Salience –Alarms Memory & Attention Display Representations –Information Representation (decomposition) –Forms of Reference (propositional, iconic, analogical) –Analog vs. digital

Cognitive Ergonomics SOME BASIC DEFINITIONS Psychology = the study of human behaviour Cognitive Psychology = the study of cognitive processes Engineering Psychology = Investigates (i.e. through research), the limits and capabilities of (human) information processing in the context of work and systems design

Cognitive Ergonomics (cont’d) Cognitive Ergonomics - "Neck-up" Ergonomics = The application of principles developed through engineering psychology research to the design and evaluation of cognitive tasks and systems development Physical Ergonomics -- "Neck-down" Ergonomics = The application of principles developed through kinesiology research to the design and evaluation of physical tasks Human Performance = For the purposes of this course refers to the performance on cognitive-based tasks (In reality almost all tasks have cognitive and physical components) Psychomotor Behaviour = The study of muscular activity resulting from mental processes

Brain vs. Mind WHERE DOES INFORMATION PROCESSING OCCUR? Mind = The capacity for thought, where thought is the integrative activity of the brain (mind is the electrical-chemical activity of the brain which produces conscious or higher level thought). Brain = The part of the central nervous system enclosed in the cranium of man and other vertebrates, consisting of a soft, convoluted mass of gray and white matter and serving to control and co-ordinate the mental and physical actions of the body.

Salience The degree to which a visual form stands out in relation to the other visible visual forms Salience is relational Each new form added changes the salience of all others

Salience example 1

Salience example 2

Salience Effective use of salience is about controlling what people see Perceptual Segmentation: what people see as a “unit” Salience: what “stands out” over other things in the display Foreground, background, alarms

Salience Perception is based on noting a difference Difference from a background, or from what was there before Salience is relative - adding another piece of information to the screen changes the salience of all the other pieces of information

Salience Is a function of movement size intensity hue saturation

General Principles Movement more salient than things that don’t move large and dull is not salient (background) large and bright is extremely salient (critical things) very bright colours (yellow) don’t have to be large to be noticeable

Approach Categorise objects as background or foreground Prioritise Foreground should be reserved for changing and dynamic information Start with low salient colours (like grey) and build up, layering

Design Errors with Salience Background layers that dominate foreground Fancy bright 3D graphics of things that never change Over use of colour to separate categories Under use of grey, overuse of colour, hues A static item is only informative once

Perceptual Segmentation Can allow large amounts of data to be processed easily People use relationships and organisation to process information into meaningful chunks Designer must group and organise the information

Reducing by Adding Organising often requires adding information to a screen x x vs. x x

Emergent Features

Old fashioned HCI Argues that you should keep things simple use only 7 colours, etc. Current approach is for more complex but coherent views

Alarms People tend to concentrate on 1 task at a time Alarms are for alerting Too many alarms and people will ignore (think car alarms!) annoying and operators will turn off Balance between alerting and annoying

Design Approaches Visual alarming –colour - yellow –salience - brightness, size –flashing - movement Auditory alarms –tones –buzzers

Alarms should... Be meaningful indicate the degree of the problem by varying its alerting characteristics allow the operator to figure out the problem if multiple alarms, only critical alarms should be presented (prioritisation)

Examples of Alarms/Salience Stove Display –Different foods cook for different times, design a display that best shows food preparation, heating, and well-doneness Coffee Maker –Best coffee is brewed at 85 degrees, +/- 10 degrees, and for maximum 8 min. Design a display that provides suitable feedback to the user. Breadmaker –Bread will crisp at 500 deg, be underbaked at 300 deg, and best duration for baking is 50 min. Design a display that warns of overbaked bread. Croissant Oven –Croissants are picky. At 350 deg for 5 min/100 grams of cookie mix, design a display that helps set the best cookie baking time