Usability Questionnaire Results - Institute of Aviation - University of ...

More documents

Recommendations

Info

2.2.1 Mimic DisplaysMimic displays present information at the level of physical function of a system (Hollan,Hutchins, McCandless, Rosenstein, & Weitzman, 1987; Bennett, 1993; Bennett & Malek, 2000).A mimic display provides representations of important components, systems, or subsystems asthey appear in the physical world. For example, a mimic display of an automobile’s fuel systemwould include a schematic outline of the vehicle with a fuel tank and gas lines and valvessuperimposed. The level of fuel would be indicated in the gas tank representation.A particularly good feature of mimic displays is their ability to show physicalconnections and limiting problems of the important components or systems. These provisionslead to better support for detection and diagnosing of faults in a system (Bennett & Malek,2000). Animation in mimic displays has also been achieved to provide additional informationabout the flow of information and resources within a system (Bennett, 1993; Bennett & Malek,2000). Part of the benefit of mimic displays comes from their pictorial realism. This refers to adisplay representation being a pictorial representation of the entity it is representing (Wickens &Hollands, 2000).Moray and Rotenberg (1989) used a type of a mimic display to display the operation of asimulated thermal hydraulic system. Participants in the experiment saw a physical representationof the thermal hydraulic system. Temperatures and the level of fluid in the tanks were directlydisplayed to aid the operator’s mental model of the current state of the system. This wasintended to aid the operator in both detection of faults in the process control and diagnose theproblems.Mimic displays are one useful way to represent information about a system. However,mimic displays do not address the issue of integrating information. The discussion will now turnto integrated displays to discuss the integration issue.2.2.2 Integrated DisplaysThe trend for displays over recent years has been to integrate various sources ofinformation into one display referred to as integrated displays. Integrated displays can bedefined as any type of display that integrates multiple sources of information into one format ordisplay. One component of integrated displays is a distinction made by Garner (1970) betweenwhat was called integral dimensions and separable dimensions. Integral dimensions weredescribed as occurring when the level on one dimension cannot be specified without identifyingthe level on another dimension. An example of this would include a point on an x-y plane. Thepoints place in space can only be determined by acknowledging both its position along the x axisand the y axis. Separable dimensions can be specified independently such as with separate lineson a line graph.Different types of integrated displays have been designed over the years. Each type ofdisplay has its own form of benefit. However, each display has potential for costs inperformance as well. Four types of integration for displays will be discussed.9
2.2.2.1 Close Spatial Proximity DisplaysThe basic feature of a close spatial proximity display is to create a “psychologicalcloseness” between elements in a display through physical manipulations (Wickens & Carswell,1995). Perhaps the most common manipulation to increase the psychological closeness is toplace elements physically close to each other in the display. An example of this occurs in thecockpit of airplanes. The directional heading and altitude reading are important informationsources for navigation and are placed close together in the cockpit. Since these informationsources are mentally linked, the spatial closeness is beneficial. The integrated one-line diagramdescribed earlier has collocated buses and voltage values in an attempt to create a psychologicalcloseness as well.Other types of proximity manipulation described by Wickens and Carswell (1995)include connections, source similarity, code homogeneity, object integration, and configuration.Connections between elements can be made through the use of lines or enclosures. An exampleof source similarity is making separate elements the same color or placing them along the sameaxis. Code homogeneity in a display will also increase proximity. As example of codehomogeneity is exemplified by using two bar graphs to represent two temperatures instead ofusing a bar graph and a round needle indicator. Object integration is defined as arranginginformation sources so that they appear to the user to be part of a single object. Finally,configuration refers to perceptual proximity created by a combination of homogeneous features,close spatial proximity, and the arrangement of sources that leads to the emergence of a newpattern.Woods, O’Brien, and Hanes (1987) examined process control in the nuclear powerdomain. They provide an example of a close spatial proximity display. The control panels innuclear power plants tend to follow the single-sensor single-indicator style of design. Woods etal. showed how simple enhancements such as boxing and lines dramatically helped a user toperceive groupings of controls and indicators. This helped to define the functional relationshipof different controls and indicators which in turn is expected to improve the ability to diagnoseproblems.2.2.2.2 Object DisplaysAn object display is defined as a graphical technique that uses several dimensions of asingle perceptual object to present multiple sources of information (Carswell & Wickens, 1987;Andre & Wickens, 1989). A characteristic of object displays is that elements are linked by linesand/or contours. For example, a square could represent one value along its dimension of widthand another value along its dimension of height. A clear benefit of object displays is that thevarious attributes of a single object are bound together in perceptual processing which leads toparallel processing (Kahneman & Henik, 1981).A particular benefit of object displays is that they often, but not always, produce anemergent feature. The theory of emergent features was first described in work by Pomerantz(Pomerantz, Sager, & Stoever, 1977; Pomerantz, 1981). One way to describe an emergentfeature is as a combination of smaller or simpler elements that produce a new relational orinteractive property (Sanderson, Flach, Buttigieg, & Casey, 1989). Object displays are more10
Page 2 and 3: ABSTRACTTraditional power system di
Page 7 and 8: 1.2 Evaluation of Integrated One-Li
Page 9: Third, false alarms are much more c
Page 13 and 14: Furthermore, configural displays ne
Page 15 and 16: calling for precise judgment of one
Page 17 and 18: found that subjects performing a vi
Page 19 and 20: 1974). This reduces visual search t
Page 21 and 22: organized as well perceptually, and
Page 23 and 24: Figure 3-1. Tabular Display280.97 p
Page 25 and 26: 3.6.2 Phase 2: TrialsParticipants i
Page 27 and 28: with multiple violations (M=3.316,
Page 29 and 30: Median # of Capacitor Closures per
Page 31 and 32: diagram display were derived from t
Page 33: effect on the bus voltages that was
Page 36 and 37: Carswell, C. M. & Wickens, C. D. (1
Page 38 and 39: Pomerantz, J. R. (1981). Perceptual

Usability Questionnaire Results - Institute of Aviation - University of ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?