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IE 327 Introduction to Work Design Dr. Andris Freivalds Class #15. Coding of Information & Visual Displays (pp. 306-316). Types of Information Quantitative – specific numbers: feet, psi Qualitative – general values: trends, up/down Status – small set of conditions: on/off/standby
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IE 327 Introduction to Work Design Dr. Andris Freivalds Class #15 IE 327
Coding of Information & Visual Displays (pp. 306-316) • Types of Information • Quantitative – specific numbers: feet, psi • Qualitative – general values: trends, up/down • Status – small set of conditions: on/off/standby • Warnings – emergency: alarms • Alphanumeric – text: signs • Representational – symbols, colors as codes • Time-phased – blinking lights IE 327
Display Modality (5 senses) IE 327
Display Dimension • Select appropriate dimension • Brightness, color, rate, size, • Absolute vs. relative judgment • Relative = direct comparison (300,000 colors) • Absolute = no direct comparison, limited • Miller’s rule = 7+2 levels IE 327
Which is Larger: A or B? IE 327
Discriminability of Codes • Just noticeable difference = minimum difference between two stimuli so as to be distinguished • Weber’s Law: JND = k S IE 327
Compatibility • Relationship of stimuli and response consistent with human expectations: ↓ RT, ↓ errors • Basic principles: • Affordance: perceived = actual property • Mapping: spatial compatibility • Direct drive • CW ↑settings • Scale readings ↑ L to R • Feedback: keyboard click IE 327
Redundancy • Present same information on two or more • Dimensions: color and intensity • Channels: auditory and visual • Decreases errors and RT • But limits potential information IE 327
Design Principles for Visual Displays-1 • Digital vs. Analog? • Precision vs. approximation • Exact value vs. trend • Watches??? IE 327
Design Principles for Visual Displays-2 Fixed scale, moving pointer: best Moving scale, fixed pointer: not good IE 327
Design Principles for Visual Displays-3 Basic features of dial: • Scale: • Major/minor tics • Progression • 10’s, 5’s best • 2’s OK • 3’s never • Pointer • Pointed • Meets smallest tic • Avoid parallax IE 327
Parallax IE 327
Design Principles for Visual Displays-4 Panel (bank of dials) design: • Use patterns • Make deviant dial conspicious • Extended lines/pointers IE 327
Design Principles for Visual Displays-5 • Minimize informational load (Miller’s Rule) • Indicator lights • Flashing creates arousal/attention • But flicker fusion rate (Movies 24/sec) • Labels • Proper size: at 20 in. → 10 pt = 22 arc min, but 1:6 strokewidth/height ratio • B on W for day, W on B for night (irradiation) • Mix upper and lower case • Warnings: bold and upper case IE 327
Design Principles for Controls - 1 Control-response ratio= amount of control move amount of response move • Low C/R = high gain • coarse control • High C/R = low gain • fine control • Optimum C/R = best response time • ↓ travel time • ↓ adjust time IE 327
Design Principles for Controls - 2 • Horizontal displays: Warrick’s principle = closest points on display & control move in same direction • Stick controls: up = increase, forward = increase?? • Different planes: CW = ↑, right-hand rule IE 327