Evaluation of a visual layering methodology for colour coding control room displays

Eighteen people participated in an experiment in which they were asked to search for targets on control room like displays which had been produced using three different coding methods. The monochrome coding method displayed the information in black and white only, the maximally discriminable method contained colours chosen for their high perceptual discriminability, the visual layers method contained colours developed from psychological and cartographic principles which grouped information into a perceptual hierarchy. The visual layers method produced significantly faster search times than the other two coding methods which did not differ significantly from each other. Search time also differed significantly for presentation order and for the method x order interaction. There was no significant difference between the methods in the number of errors made. Participants clearly preferred the visual layers coding method. Proposals are made for the design of experiments to further test and develop the visual layers colour coding methodology.     

Eye movement and pupillary response indices of mental workload during visual search of symbolic displays

Eye movement and pupillary response measures (in addition to search time and accuracy) were collected as indices of visual workload during two experiments designed to evaluate the addition of colour coding to a symbolic tactical display. Displays also varied with regard to symbol density and the type of information participants were required to abstract from the display. These variables were factorially manipulated to examine the effects of colour coding in conditions of varying difficulty. In Experiment 1 (n = 8), search time and the number of eye fixations were affected by all variables and in a similar manner; fixation dwell time and the pupillary response dissociated from the other measures. Compared to monochrome displays, colour coding facilitated search (reduced search time, but not accuracy) during exhaustive search, but had no effect during self-terminating search. Experiment 2 (n = 8) was a replication of Experiment 1 with a pseudo-search control condition added to examine further the pupillary response measures: in particular, to assess the effects of the physical parameters of the displays, and to verify the findings of Experiment 1. Pupillary response measures were sensitive to the information processing demands of the search task, not merely to the physical parameters of the display. Further, the search time, accuracy, and eye movement results from the active search condition generally replicated Experiment 1, but the fixation dwell time data did not. These between-study differences were interpreted as indicating the importance of participant search strategy.     

Ocular measures of redundancy gain during visual search of colour symbolic displays

Sixteen observers participated in a visual search experiment in which colour coding, search type, and the amount of pre-search information available to the observers were varied. Observers searched simulated symbolic tactical displays to find the number of target symbols (i.e. exhaustive search) or the quadrant of the display in which a single target symbol was located (i.e. self-terminating search). Displays varied in the way in which the symbology was colour coded: colour was either relevant (i.e. redundant with symbol shape) or irrelevant (orthogonal to symbol shape), or the display was monochrome. Half of the observers were cued with regard to the coding scheme prior to display onset, while the other observers were not. There was no overall difference in search time or accuracy, number of eye fixations, or pupillary response between cued and non-cued observers, but only because cued and non-cued observers used the coding schemes differently. Redundancy gain was only evident for cued observers, who searched colour relevant displays faster and with fewer fixations than colour irrelevant or monochrome displays. Non-cued observers' search pattern did not differ across colour coding schemes, but they searched colour irrelevant and monochrome displays faster than the cued observers. Differences between cued and non-cued observers' search strategy are discussed with regard to their implications for design and evaluation of colour multipurpose displays.     

Eye movement behaviour viewing colour-coded and monochrome avionic displays

Abstract

This paper reports on two experiments in which subjects' eye movement behaviour was monitored while they searched for target information in colour coded and monochrome horizontal situation indicator (HSI) displays. The first experiment required subjects to locate and report alphanumeric information associated with the active waypoint on the displayed flightpath. Initial fixations in the display were more accurately directed to the target information when it was redundantly colour coded compared with when it was coded by shape and relative positional codes. Fewer fixations and a shorter time were required to locate the colour coded target and verbally report the relevant information. The time advantage of colour coded displays compared with monochrome displays was greatest for visually cluttered displays. In the second study there was no advantage of a coloured display when the task was to count all the displayed waypoint symbols on the flight path. The lack of any benefit for colour coding was a result of waypoint symbols having strong positional predictability due to their relationship to the displayed flightpath in both the colour and monochrome displays. The implication from these results is that colour coded information confers an advantage over a spatial code for targets at unknown spatial location but less benefit when target location can be predicted by other visual cues.     

With flying colours: Pilot performance with colour-coded head-up flight symbology

The manipulation of colour in display symbology design has long been recognised as a method to improve operator experience and performance. Recent developments in colour head-up display (HUD) and helmet-mounted display (HMD) technology underline the necessity to understand the human factors considerations of symbology colour coding against conventional monochrome symbology formats. In this low-fidelity desktop human-in-the-loop experiment, the colour of flight symbology on an overlaid symbology set was coded as a redundant cue to indicate the accuracy of professional and non-professional pilots’ flight profile across a range of simulated flight manoeuvres. The main finding of this study was that colour coding flight symbology supported the manual flying performance of both professional and non-professional pilots. Notably, colour-coding of the bank indicator and airspeed tape minimised performance error during turning and altitude change manoeuvres, respectively. The usability of colour coded symbology was also rated higher than the monochrome symbology. We conclude that colour coded HUD/HMD symbology is preferred by the user and may improve performance during low workload manual flying tasks. A fuller understanding of performance and workload effects will require future studies to employ higher workload flying tasks and examine the utility of colour coding within higher fidelity environments.     

Attentional filtering in the design of electronic map displays: a comparison of color coding,intensity coding,and decluttering techniques

In a series of experiments color coding, intensity coding, and decluttering were compared in order to assess their potential benefits for accessing information from electronic map displays. Participants viewed electronic battlefield maps containing 5 classes of information discriminable by color or intensity, or, in the decluttering condition, displayed or removed entirely by a key press. Participants were asked questions requiring them to focus on objects within a class (objects presented at the same color or intensity) or to integrate data between objects in different classes (objects presented at different colors and intensities). The results suggested that the benefits of color and intensity coding appear to be in segregating the visual field rather than calling attention to the objects presented at a certain color or intensity. Interactivity proved to be a disadvantage; the time cost of information retrieval outweighed the time benefits of presenting less information on the display or even allowing map users to customize their displays. Potential applications of this research include a cost-benefit analysis for the use of 3 attentional filtering techniques and an attempt to quantitatively measure map complexity.     

Information availability in 2D and 3D displays

Why are 3D displays good for rapidly appreciating the third dimension of scenes? We show that information availability is more important than the 3D display format. Participants engaged in visual search for the attributes of altitude and pitch for coding schemes. This design let us disentangle the display format and information coding scheme so that we could properly evaluate the effect of each on performance     

Self-generated complexity and human-machine interaction

A novel approach to measure the self-generated complexity of human-machine interaction is presented. A complexity measure that relies solely on information-theoretic quantities is defined. An efficient estimation procedure for the complexity measure is introduced. The theoretical framework is validated by a study of human interaction with electronic map displays. Thirty experienced master mariners participated. The task was to search for multiple vessel symbols under time pressure. Samples from the visual scanpath, as well as manual responses, were acquired. The workloads due to time pressure, the number of symbol clusters on the display, and the map scenario were systematically varied. The results of an analysis of variance (ANOVA, /spl alpha/=0.05) show a significant complexity decrease when the time pressure (or workload) is increased. The workload effect on the complexity of master mariners' visual scanpath was stronger than on their manual response. There was also a significant effect of the number of symbol clusters on the display: a display with two clusters showed a significantly higher search complexity for manual response than a nonclustered display.     

Effects of display method,number of message lines,and text colour on Chinese comprehension and subjective preferences for an LED display

This study investigated the effects of display method, number of message lines and text colour on comprehension performance and subjective preferences for reading Chinese on a light‐emitting diode display. The factors and levels studied were: two text display methods (rapid serial visual presentation ‘rapid serial visual presentation (RSVP)’ and paged view scrolling), four numbers of message lines displayed at a time (one to four lines) and three text colours (amber, green and red). The RSVP method resulted in higher comprehension scores than the paged view scrolling method, and the green text produced better comprehension score than amber or red. However, the paged view scrolling received better subjective evaluation ratings than the RSVP method. A multiline display was found to be superior to a single‐line display for both comprehension scores and subjective evaluations. The results here provide useful ergonomics recommendations for choice of appropriate display method and format setting for presenting Chinese messages on light‐emitting diode displays.     

Effects of in-vehicle warning information displays with or without spatial compatibility on driving behaviors and response performance

A driving simulator study was conducted to evaluate the effects of five in-vehicle warning information displays upon drivers' emergent response and decision performance. These displays include visual display, auditory displays with and without spatial compatibility, hybrid displays in both visual and auditory format with and without spatial compatibility. Thirty volunteer drivers were recruited to perform various tasks that involved driving, stimulus-response, divided attention and stress rating. Results show that for displays of single-modality, drivers benefited more when coping with visual display of warning information than auditory display with or without spatial compatibility. However, auditory display with spatial compatibility significantly improved drivers' performance in reacting to the divided attention task and making accurate S-R task decision. Drivers' best performance results were obtained for hybrid display with spatial compatibility. Hybrid displays enabled drivers to respond the fastest and achieve the best accuracy in both S-R and divided attention tasks.     

LCD versus CRT displays: a comparison of visual search performance for colored symbols

Visual search performance for tactical symbols was examined with liquid-crystal (LCD) and cathode-ray tube (CRT) displays. Twenty-four adult participants (19 men, 5 women; mean age 41 years) searched for navy tactical display symbols on a map background. LCD and CRT displays of similar size and resolution (52 cm diagonal, 1280 x 1024 pixels) were used. Viewing angle (0 degrees vs. 60 degrees of azimuth), set size, target color (blue, red, or white), target presence, and search type (feature vs. conjunction) were also manipulated. Participants showed reduced sensitivity for red and blue symbols viewed 60 degrees off axis with the LCD relative to on-axis LCD, or to the CRT on or off axis. Colored symbols viewed off axis on the LCD produced longer response times in feature search and lower search efficiency in conjunction search. The results argue against the use of current LCD technology when off-axis viewing is likely and color coding is used.     

Selected graph design variables in four interpretation tasks: a microcomputer-based pilot study

A pilot study was undertaken to assess the efficacy of selected graph types and information coding schemes in producing quick and accurate graph interpretation. Point-plots, line graphs, bar graphs, and three-dimensional bar graphs were constructed and displayed using an IBM-PC microcomputer with colour monitor. The effectiveness of each of these graph types, as well as the coding scheme used within each (colour versus monochrome), was investigated using 32 subjects in four separate experiments involving either point-reading, point-comparison, trend-reading, or trend-comparison tasks. Dependent measures including task completion time, graph interpretation error, subjective mental workload rating, and graph preference rating were obtained. In three of the tasks, colour-coded graphs were associated with lower task completion time, lower rated mental workload, and higher rated preference than monochrome graphs. However, there were no differences in subjects' error scores between colour and monochrome coding for any of the tasks. For the point-reading task, the three-dimensional bar graphs were less effective than the other graph types, though there were no differences among graph types for the other three tasks. Implications for graph design given specific data interpretation tasks are discussed, based on the results of the four experiments and related literature.     

Fabrication and performance characteristics of black‐dielectric electroluminescent 160 × 80‐pixel displays

Abstract— We report on recent technological progress in black‐dielectric electroluminescent (BDEL) displays. Fabrication of the first monochrome BDEL 160 × 80‐pixel 4‐in. displays driven with commercial low‐power (<5 W) drive circuitry is presented. Preliminary results on blue‐dielectric EL full‐color displays are also reported. Improvements in both BDEL display performance and display manufacturability underscore the recent development path.     

Smooth rotation of 2-D and 3-D representations of terrain: an investigation into the utility of visual momentum

OBJECTIVE: The potential advantage of visual momentum in the form of smooth rotation between two-dimensional (2-D) and three-dimensional (3-D) displays of geographic terrain was examined. BACKGROUND: The relative effectiveness of 2-D and 3-D displays is task dependent, leading to the need for multiple frames of reference as users switch tasks. The use of smooth rotation to provide visual momentum has received little scrutiny in the task-switching context. A cognitive model of the processes involved in switching viewpoints on a set of spatial elements is proposed. METHODS: In three experiments, participants judged the properties of two points placed on terrain depicted as 2-D or 3-D displays. Participants indicated whether Point A was higher than Point B, or whether Point B could be seen from Point A. Participants performed the two tasks in pairs of trials, switching tasks and displays within the pair. In the continuous transition condition the display dynamically rotated in depth from one display format to the other. In the discrete condition there was an instantaneous viewpoint shift that varied across experiments (Experiment 1: immediate; Experiment 2: delay; Experiment 3: preview). RESULTS: Performance after continuous transition was superior to that after discrete transition. CONCLUSION: The visual momentum provided by smooth rotation helped users switch tasks. Application: The use of dynamic transition is recommended when observers examine multiple views of terrain over time. The model may serve as a useful heuristic for designers. The results are pertinent to command and control, geological engineering, urban planning, and imagery analysis domains.     

New Products

According to Genisco Computers, the GCT-3032-8 graphics/imaging postprocessor significantly extends the capability of high-resolution (1280x1024x8) color or monochrome display systems.     

Color reproduction with a various number of sub‐pixels

Monochrome reflective‐type displays are widely used for portable reading applications such as electric papers because this type does not need a back light unit and can be used outdoors for a long time. Color reflective‐type displays without back light units are desired to expand the market further. The current color reproduction is based on three sub‐pixel red, green and blue (RGB) methods, and when used in reflective type, its luminance is reduced to a third of that of monochrome type. Adding a white sub‐pixel to the current method can improve the luminance, making the sub‐pixel number four. However, in the case of a high resolution display with a four‐sub‐pixel method, the pixel structure is complex, and the luminance improvement may be limited. Instead of increasing the sub‐pixel number, two sub‐pixel methods are investigated. These methods can improve luminance with limited color gamut. The performances are compared with those of other methods quantitatively.     

Effects of curved computer displays on visual performance,visual fatigue,and emotional image quality

This study investigated the effects of the curvature of curved computer displays on the visual performance, fatigue, and emotional image quality experienced by users during the performance of visual tasks. The characteristics of curved displays were compared and analyzed for different curvatures to investigate whether the curved displays showed improvements in terms of convenience of use when compared with flat displays. The visual performance results for the evaluated displays can be classified into three groups according to their response times, as (2000R = 2500R) > (3000R) > (3800R = 4500R = Flat). The visual fatigue results for average pupil size during a search task was 3.468 mm for flat and 3.355 mm for 2000R. This means that a 2000R curved display was found to be easier to use and thus generated less visual fatigue than a flat display when performing the same visual search task. Further, the results indicated that visual performance improved and visual fatigue decreased significantly as curvature increased. In this study, a curvature limit of 1700R was derived, when considering the image distortion of a 34‐in 21:9 curved display, and there was found to be no difference in the emotional image quality at curvatures greater than 2000R.     

Target acquisition with UAVs: vigilance displays and advanced cuing interfaces

Vigilance and threat detection are critical human factors considerations in the control of unmanned aerial vehicles (UAVs). Utilizing a vigilance task in which threat detections (critical signals) led observers to perform a subsequent manual target acquisition task, this study provides information that might have important implications for both of these considerations in the design of future UAV systems. A sensory display format resulted in more threat detections, fewer false alarms, and faster target acquisition times and imposed a lighter workload than did a cognitive display format. Additionally, advanced visual, spatial-audio, and haptic cuing interfaces enhanced acquisition performance over no cuing in the target acquisition phase of the task, and they did so to a similar degree. Thus, in terms of potential applications, this research suggests that a sensory format may be the best display format for threat detection by future UAV operators, that advanced cuing interfaces may prove useful in future UAV systems, and that these interfaces are functionally interchangeable.     

Multiple two-dimensional displays as an alternative to three-dimensional displays in telerobotic tasks

In this study a multiple-view two-dimensional (2D) display was compared with a three-dimensional (3D) monocular display and a 3D stereoscopic display using a simulated telerobotic task. As visual aids, three new types of visual enhancement cues were provided and evaluated for each display type. The results showed that the multiple-view 2D display was superior to the 3D monocular and the 3D stereoscopic display in the absence of the visual enhancement depth cues. When participants were provided with the proposed visual enhancement cues, the stereoscopic and monocular displays became equivalent to the multiple-view 2D display. Actual or potential applications of this study include the design of visual displays for teleoperation systems.     

Multisensory teamwork: using a tactile or an auditory display to exchange gaze information improves performance in joint visual search

In joint tasks, adjusting to the actions of others is critical for success. For joint visual search tasks, research has shown that when search partners visually receive information about each other’s gaze, they use this information to adjust to each other’s actions, resulting in faster search performance. The present study used a visual, a tactile and an auditory display, respectively, to provide search partners with information about each other’s gaze. Results showed that search partners performed faster when the gaze information was received via a tactile or auditory display in comparison to receiving it via a visual display or receiving no gaze information. Findings demonstrate the effectiveness of tactile and auditory displays for receiving task-relevant information in joint tasks and are applicable to circumstances in which little or no visual information is available or the visual modality is already taxed with a demanding task such as air-traffic control. Practitioner Summary: The present study demonstrates that tactile and auditory displays are effective for receiving information about actions of others in joint tasks. Findings are either applicable to circumstances in which little or no visual information is available or when the visual modality is already taxed with a demanding task.