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.     

A comparison of colour and visual texture as codes for use as area symbols on thematic maps

Three experiments compared colour and texture as methods of coding area symbols for thematic maps. Most previous research has been limited to displays with, at most, eight codes. This study employed displays containing 16 types of symbol coded either by colour, texture, or a non-redundant combination of the two. Symbols coded by colour, or a combination of colour and texture were much easier to find than symbols coded by texture alone. Point symbols were easier to locate against a coloured background than a textured background. Texture codes may be slightly easier to remember than colour codes but the difference, if any, is small.     

The effects of target location and target distinction on visual search in a depth display

Research of human-centered computing systems in industry should not avoid advances in visual display technology for safety, warning, and interaction. Novel 3D displays that present information in real depth offer potential benefits. Previous research has studied depth in visual search but depth was mostly not realized by real physical separation. Many areas of Human Factors could be augmented with the study and evaluation for operation of novel 3D displays. Such a study was presented to better understand the effects of real physical depth in association with depth redundantly coded with another feature (an additional mark on a target) distinguishing it from distracters and target location on visual search in a depth display. Target location was studied as the row or column in the visual field of view the target was positioned and also in terms of eccentricity outwardly from the center of the display. In general, depth was found to be of benefit when redundantly coded with another attribute for guiding attention. Targets were not found as fast when the target’s location was further from the center fixation point, and interactions between target distinction (depth, mark, or depth+mark) and target location provide implications for designers.     

Colour in map displays: issues for task-specific display design

Colour is generally regarded as a desirable property of computer displays chiefly because it supports users' preattentive visual processes, such as texture segregation, which rapidly organize and structure screen information. This paper examines the use of colour in computerized map displays of the sort used by geographic information systems. In particular, it focuses on the perception of patterns formed by subclasses of map symbols, defined by colour or shape. Three experiments are reported which confirm the utility of colour, but which also identify two potential problems: interference of task-irrelevant colour and superficial processing of spatial configurations of colour-defined symbols. These findings support a general argument that colour should not be preferred automatically, but rather its utility depends on the cognitive demands of the task for which the display is designed.     

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.     

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.     

Head up versus head down: the costs of imprecision, unreliability, and visual clutter on cue effectiveness for display signaling

We conducted 2 experiments to investigate the clutter-scan trade-off between the cost of increasing clutter by overlaying complex information onto the forward field of view using a helmet-mounted display (HMD) and the cost of scanning when presenting this information on a handheld display. In the first experiment, this trade-off was examined in terms of the spatial accuracy of target cuing data in a relatively sparse display; in the second, the spatial accuracy of the cue was varied more radically in an information-rich display. Participants were asked to detect and identify targets hidden in the far domain while performing a monitoring task in the near domain using either an HMD or a handheld display. The results revealed that on a sparse display, the reduced scanning from the HMD presentation of cuing out-weighed the costs of clutter for cued targets, regardless of cue precision, but no benefit was found for uncued targets. When the HMD displayed task-irrelevant information, however, target detection was hindered by the extraneous clutter in the forward field of view relative to the handheld display condition, and this cost of clutter increased as the amount of data that needed to be inspected increased. Potential applications of this research include the development of design considerations for head-up displays for aviation and military applications.     

Effects of colour coding with different symbol sets on retrieval time for a keeping-track task

Two experiments were carried out to examine the effects of colour, shape and colour-shape codes, for different retention-interval and task conditions, on the time taken to retrieve target information from memory in a keeping-track task. The first experiment used ‘filled’ symbols, and the second experiment used ‘hatched’ symbols. In the first experiment, the response time was faster across tasks and retention intervals with colour-shape coding or colour coding than with shape coding, regardless of whether or not the targets were updated. However, the benefit of both colour conditions was greater for the case in which the targets were updated while the subjects performed a distractor task during the retention interval; i.e. the colour showed a greater resistance to interference effects. Colour-shape coding was superior to colour coding across tasks and under specific retention-interval/update conditions. In the second experiment, the response time was faster with colour-shape coding than with shape coding for both the update and no-update conditions, but this advantage was more pronounced in the latter case, owing to a decrease in the response time for colour-shape coding with no updates. Finally, the response time was faster with colour coding than shape coding in the no-update condition, and was faster with colour-shape coding than with colour coding in the update condition. Taken together, the findings suggested that, in situations where it is important to retrieve information quickly, information should be coded by colour-shape coding rather than by colour or shape coding, regardless of the symbol set used. Also, the relationships between coding conditions differed considerably with different symbol sets, implying that the symbol set used can play a crucial role in the optimization of coding effectiveness.     

Color coding of control room displays: the psychocartography of visual layering effects

OBJECTIVE: To evaluate which of three color coding methods (monochrome, maximally discriminable, and visual layering) used to code four types of control room display format (bars, tables, trend, mimic) was superior in two classes of task (search, compare). BACKGROUND: It has recently been shown that color coding of visual layers, as used in cartography, may be used to color code any type of information display, but this has yet to be fully evaluated. METHOD: Twenty-four people took part in a 2 (task) x 3 (coding method) x 4 (format) wholly repeated measures design. The dependent variables assessed were target location reaction time, error rates, workload, and subjective feedback. RESULTS: Overall, the visual layers coding method produced significantly faster reaction times than did the maximally discriminable and the monochrome methods for both the search and compare tasks. No significant difference in errors was observed between conditions for either task type. Significantly less perceived workload was experienced with the visual layers coding method, which was also rated more highly than the other coding methods on a 14-item visual display quality questionnaire. CONCLUSION: The visual layers coding method is superior to other color coding methods for control room displays when the method supports the user's task. APPLICATION: The visual layers color coding method has wide applicability to the design of all complex information displays utilizing color coding, from the most maplike (e.g., air traffic control) to the most abstract (e.g., abstracted ecological display).     

Information structure and the relative efficacy of tables and graphs

Users and system designers often prefer to display information with graphs rather than with tables. However, empirical studies that compared task performance with the two display types frequently revealed either an advantage of tables over graphs or no differences between the displays. This apparent contradiction may result from previous studies in which the importance of the structure that usually exists in displayed information is overlooked. We predict that graphic displays will have an advantage over tables when the displayed information has structure and when this structure is relevant for the task. These conditions generally exist in the actual use of information displays, but have seldom been assessed in experiments. In the present study participants in an experiment performed an information extraction task and a prediction task with unstructured or structured data and with different levels of prior information about the structure. The results showed that the information structure and prior knowledge about the existence of structure affected the advantage of graphic displays over tables when task performance depended on the use of structure. Existing approaches to the study of displays were analyzed in view of these findings. Actual or potential applications of this research include the development of better displays for process control and decision support and better operator training programs.     

Evaluation of formats for aircraft control/display units

Control/display unit (CDU) technology has been advancing more rapidly than the human factors research needed to establish guidelines for the design of display formats. Such guidelines must be established and followed to ensure effective and efficient human performance in the cockpit environment. A preliminary study which addressed the issue of defining an optimal CDU display format design was completed.

Subjects were asked to search visually alphanumeric displays for a single piece of information and indicate when it was found. Data were collected on the elapsed time to isolate the information as well as the accuracy of the information retrieval. Ten formats of two information densities each were evaluated. Each format contained labels and associated data for typical flight information such as communications data (radio type and frequency) and navigation data (waypoint identifier, longitude and latitude). The ten basic format designs were developed by changing the location relationship between the labels and their associated data.

Data were collected while subjects did and did not perform a two-dimensional tracking task. Preliminary findings indicate that both format design and density affect operator response time and response accuracy. Implications of the results for the design of cockpit displays are discussed.     

Raster graphics display technology: a review

Performance and technologies of monochrome and polychromatic raster CRT visual display units are reviewed. For computer graphics, image quality is affected most by parameters such as size, resolution, luminance, contrast ratio, geometric distortion, flicker and video bandwidth. For polychromatic displays, chromaticity and convergence are also important parameters. Comparisons of 480 mm VDUs show that monochrome untis are less expensive and have better performance except for the use of colour to discriminate between different entities on the screen. Some typical graphics processor output head architectures are reviewed together with trends in display technology.     

Partitioning visual displays aids task-directed visual search

We reduced time to detect target symbols in mock radar screens by adding perceptual boundaries that partitioned displays in accordance with task instructions. Targets appeared among distractor symbols either close to or far from the display center, and participants were instructed to find the target closest to the center. Search time increased with both number of distractors and distance of target from center. However, when close and far regions were delineated by a centrally presented "range ring," the distractor effect was substantially reduced. In addition, eye movement patterns more closely resembled a task-efficient spiral when displays contained a range ring. Results suggest that the addition of perceptual boundaries to visual displays can help to guide search in accordance with task-directed constraints. Actual or potential applications of this research include the incorporation of perceptual boundaries into display designs in order to encourage task-efficient scanpaths (as identified via task analysis and/or empirical testing).     

High‐resolution and high‐brightness full‐colour “Silicon Display” for augmented and mixed reality

High‐brightness micro‐LED display bonded onto silicon backplane has been successfully demonstrated. The 0.38‐inch full‐colour active matrix LED microdisplay system consists of 352 × 198 pixels. Each pixel is 24 μm square composed of red, green, and blue (RGB) subpixels corresponding to a pixel resolution of 1053 ppi. Quantum‐dot materials are formed on III‐nitride blue micro‐LED array to convert blue light into red and green for full‐colour operation. We have confirmed that this microdisplay, which we call “Silicon Display” has wide colour gamut exceeding 120% of sRGB. We describe the advantage of this colour‐converting approach for the full‐colour micro‐LEDs. Progress toward higher resolution is also described. Brightness of more than 30 000 cd/m² has been confirmed at a driving current density of 4 A/cm² for 3000 ppi blue monochrome micro‐LED prepared for full‐colour Silicon Display. We believe our “Silicon Display” is ideally suited for near‐to‐eye displays for augmented and mixed reality.     

Looking,Sequential Redundancy,Transfer, and Age in Early Keyboard Learning

Groups of older and younger subjects were given one-hour sessions on a simple keyboard task. In the first experiment the major variable was the extent to which subjects could see what they were doing while carrying out a 5- or 10-alternative task. In the second experiment subjects performed the task with a positional or an alphabet in-line display using either a completely random or a structured input sequence. In the third experiment, the effect of pre-training on a positional display on subsequent performance with an alphabet in-line display was examined. It was found that both older and younger subjects made more errors when they could not see either keyboard or their hands; that older subjects could take advantage of sequential redundancy only when using an alphabet in-line display; and that older subjects did not benefit from positional display pre-training.     

Target cuing in visual search: the effects of conformality and display location on the allocation of visual attention

Two experiments were performed to examine how frame of reference (world-referenced vs. screen-referenced) and target expectancy can modulate the effects of target cuing in directing attention for see-through helmet-mounted displays (HMDs). In the first experiment, the degree of world referencing was varied by the spatial accuracy of the cue; in the second, the degree of world referencing was varied more radically between a world-referenced HMD and a hand-held display. Participants were asked to detect, identify, and give azimuth information for targets hidden in terrain presented in the far domain (i.e., the world) while performing a monitoring task in the near domain (i.e., the display). The results of both experiments revealed a cost-benefit trade-off for cuing such that the presence of cuing aided the target detection task for expected targets but drew attention away from the presence of unexpected targets in the environment. Analyses support the observation that this effect can be mediated by the display: The world-referenced display reduced the cost of cognitive tunneling relative to the screen-referenced display in Experiment 1; this cost was further reduced in Experiment 2 when participants were using a hand-held display. Potential applications of this research include important design guidelines and specifications for automated target recognition systems as well as any terrain-and-targeting display system in which superimposed symbology is included, specifically in assessing the costs and benefits of attentional cuing and the means by which this information is displayed.     

Benefits of color coding weapons symbology for an airborne helmet-mounted display

We assessed the advantages of a color-coded weapons symbology for a helmet-mounted display over monochrome symbology by measuring military pilots' performance while they flew air-to-air combat in a simulator. The pilots fired missiles significantly sooner without sacrificing probability of kill when using the color-coded symbology, demonstrating a substantial practical benefit of color. Actual or potential applications of this work include the design of color codes for helmet-mounted and other displays that use complex symbology to assist performance on cognitively challenging tasks.     

Spatialization design: comparing points and landscapes

Spatializations represent non-spatial data using a spatial layout similar to a map. We present an experiment comparing different visual representations of spatialized data, to determine which representations are best for a non-trivial search and point estimation task. Primarily, we compare point-based displays to 2D and 3D information landscapes. We also compare a colour (hue) scale to a grey (lightness) scale. For the task we studied, point-based spatializations were far superior to landscapes, and 2D landscapes were superior to 3D landscapes. Little or no benefit was found for redundantly encoding data using colour or greyscale combined with landscape height. 3D landscapes with no colour scale (height-only) were particularly slow and inaccurate. A colour scale was found to be better than a greyscale for all display types, but a greyscale was helpful compared to height-only. These results suggest that point-based spatializations should be chosen over landscape representations, at least for tasks involving only point data itself rather than derived information about the data space.     

An experimental comparison of test and symbols for in-car reconfigurable displays

As cars become more sophisticated, there is a corresponding increase in the range of information which needs to be presented to drivers. This increased information load is beyond the scope of conventional technology; space requirements on the dashboard limit the number of displays, which can be employed. The study reported in this paper is based on the premise that centralized information presentation could be employed for in-car warming systems. Forty subjects were tested on a computer-based task, in which they had to rate the urgency of displayed information. The information was presented in one of four formats: symbols only, symbols plus title, symbols plus action, or symbol, title and action. Results show that the most effective type of display for urgency rating was symbol plus action, and that symbol, title and action produced the fastest reaction times. These results are considered in terms of previous research, and implications for the design of in-car warnings are discussed.     

Optimization suggestions for instrument‐cluster information using displays

Abstract— Suggestions are proposed to improve the way information is presented with heads‐down displays (HDDs) to optimize the information and potentially reduce the duration and frequency of scans necessary by the driver to read the information. Using color as a secondary channel of information on vehicle meters could reduce scan frequency by increasing awareness in driver' s peripheral vision. Only showing relevant portion of scales can reduce the overall necessary area for display information and possibly reduce the number of fixations necessary to read the information from that area. Larger displays can be optimized with same considerations as other displays, butthe size creates an easier opportunity to be filled with information in a way that ends up distracting the driver. Elaborate or complex graphics that emphasize the full abilities of larger displays are probably best limited to non‐driving conditions. Color displays also have the potential benefit of reconfigurability, which could have a significant impact on how information is presented. Reconfiguration concepts suggested include only showing information of interest, font‐size adjustment, and using GPS information to augment speed information based on traffic, time of day, and weather conditions.