Displays INSY 3020/7976/ENH 670

Display Any method for presenting information which uses some intervening mechanism or device to convey information from its source to the person. Types of Displays

When designing displays, consider 3 levels of representation 1. The physical (real world) system-human, machine, and environmental characteristics 2. The users internal representation (internal model) 3. The critical interface between 1 and 2 – the display surface upon which changes in the system are presented to the user

Display Design Our goal is to apply what we know about sensation and perception to the design of displays.Our goal is to apply what we know about sensation and perception to the design of displays. Displays are supposed to present information.Displays are supposed to present information.

Visual vs. Auditory Use visual if:Use visual if: –Complex message. –Long message. –It needs to be seen later. –Does not need immediate action. –The environment is noisy (sounds).

Visual vs. Auditory Use auditory if:Use auditory if: –The message is short and simple. –Not referred to later. –Immediate action. –Overburdened with visual information.

Visual Displays Static (e.g., signs) vs. dynamic (e.g., gauges).Static (e.g., signs) vs. dynamic (e.g., gauges). Use depends on information being conveyed + environment.Use depends on information being conveyed + environment.

Static Displays Overall influences on effectiveness:Overall influences on effectiveness: –Conspicuity: How well it attracts attention. Influences: Be where people are looking.Be where people are looking. Stand out to increase chances of fixation on the fovea.Stand out to increase chances of fixation on the fovea. Few distracters (or consider them in design).Few distracters (or consider them in design). –Feature search: Pop-out, fast,easy. –Conjunction search: Demands attention, slow, hard. Example: Central mounted brake light.Example: Central mounted brake light.

Static Displays Effect of distracters:Effect of distracters: –Feature search (find the blue S): –Conjunction search (find the green T): T X T X X X T X T X X T X T T X T X T S X T X X X T T X T X T X X X T X T X T T X T T X T X T T X T X X X T T X

Static Displays Overall influences on effectiveness:Overall influences on effectiveness: –Visibility: Visible under all viewing conditions. –Legibility: How easily perceived it is. Influences: Contrast ratio (black on white best).Contrast ratio (black on white best). Font.Font.

Static Displays Overall influences on effectiveness:Overall influences on effectiveness: –Readability: Function of: Intelligibility: Clear, few words, no abbreviations, precise.Intelligibility: Clear, few words, no abbreviations, precise. Emphasis: Make the important parts stand out.Emphasis: Make the important parts stand out. Standardization: Use standards where possible (e.g., red).Standardization: Use standards where possible (e.g., red). –Avoid ambiguity. For example: GATE

Example Original Sentence: New and Improved Sentence:

Static Displays Alphanumeric displays:Alphanumeric displays: –Used to convey detailed information. –Possible drawbacks: Confusability of symbols. Combining into words and sentences makes this less of a problem.Confusability of symbols. Combining into words and sentences makes this less of a problem. Operator must be literate.Operator must be literate.

Static Displays Alphanumeric displays:Alphanumeric displays: –Influences on perceptibility: Contrast ratio: High is good.Contrast ratio: High is good. Optimize stroke width for situation (e.g., color combinations).Optimize stroke width for situation (e.g., color combinations). Size: Optimize.Size: Optimize. Poorer contrast ratio can be offset with larger size, and smaller size can be offset with higher contrast ratio.Poorer contrast ratio can be offset with larger size, and smaller size can be offset with higher contrast ratio.

Static Displays Alphanumeric displays:Alphanumeric displays: –Influences on perceptibility: Font: Three types:Font: Three types: –Serif (this font). –Sans serif ( this font ). –Script –Script (this font). –Other. –Serif is generally easier to perceive because it contains more information.

Static Displays Alphanumeric:Alphanumeric: –Influences on perceptibility: Display format:Display format: –Density (total area): How much of the display area is covered. Keep this low. –Density (local): Density immediately surrounding a character. Intermediate is good. –Grouping. Helps if the grouping is relevant. –Layout complexity: Too much hampers performance.

Dynamic Displays Display information that changes over time (fuel level, mileage, heading).Display information that changes over time (fuel level, mileage, heading). Can be analog or digital:Can be analog or digital: –Digital preferred for reading exact values. Trend requires memoryTrend requires memory –Analog: Can be a fixed background with a moving pointer or a moving background with a fixed pointer.Can be a fixed background with a moving pointer or a moving background with a fixed pointer. Preferred for qualitative readings (trend), check reading, setting values, tracking, and spatial orientation.Preferred for qualitative readings (trend), check reading, setting values, tracking, and spatial orientation.

Guideline for Designing Analog Displays 1. Understand all the information needs of the user. 2. A moving pointer against a fixed scale is a preferred design. 3. Do not mix types of pointer (moving elements) indicators when they are used for related functions 4. A numerical increase in a parameter should be associated with a naturally expected movement on the display 5. In manually controlled displays, the control (lever, knob) should move the pointer, not the scale 6. Use a moving pointer-fixed scale display when slight, variable movements or changes in a system parameter are important.

Dynamic Displays Optimal arrangements:Optimal arrangements: –Frequency of use principle: The ones needed the most should be easily fixated on the fovea. –Sequence of use principle: Arrange to minimize eye movements. Use link analysis to figure this out. –Gestalt grouping principles: Group like functions together.

Visual Displays Signal and warning lights:Signal and warning lights: –Classify possible messages on this scale: Warning: Immediate attention and immediate response.Warning: Immediate attention and immediate response. Caution: Immediate attention, rapid response.Caution: Immediate attention, rapid response. Advisory: Increase awareness of situation.Advisory: Increase awareness of situation. –Arrange information to make the most important the most visible. Center (foveal), large, bright, high contrast, flashing (that’s why the blink feature in html is annoying).Center (foveal), large, bright, high contrast, flashing (that’s why the blink feature in html is annoying). Use standards and background knowledge consistently. For example, red for warnings, yellow for caution (reversing that slows responding).Use standards and background knowledge consistently. For example, red for warnings, yellow for caution (reversing that slows responding).

Display Compatibility Degree to which codes and symbols in the display correspond to the conceptual association of people The degree to which the position and location of display information agrees with the user’s “mental model” of the system. The relationship between the movement of the display and the response of the system.

Display Conceptual Compatibility America’s 1 st permanent repository for high level of radioactive waste US DOE needs to design a system of markers and monuments to ward off intruders from the site Displays must be effective through the year AD Yucca Mountain

Example: Orientation Compatibility Violated Fixed Pointer Moving Scale Moving Pointer Fixed Scale

Summary What we learned about sensation, perception, and information theory has a big impact on optimal display design. Failing to pay attention to these facts will result in system failure.What we learned about sensation, perception, and information theory has a big impact on optimal display design. Failing to pay attention to these facts will result in system failure.