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.     

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.     

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).     

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.     

Effects of displacement magnitude and direction of auditory cues on auditory spatial facilitation of visual search

OBJECTIVE: The objective of this study is to examine the effects of cue error on auditory spatial facilitation (ASF) of visual search. BACKGROUND: ASF is the reduction in time needed to locate and identify a visual target when an auditory cue is presented at the location of the target. Although ASF has been shown to occur when the auditory cue coincides with the target location, it is important to determine whether facilitatory effects are also evident when the cue is displaced. METHOD: Participants performed a visual search task in the presence of an auditory cue that was presented at the center of the screen (uninformative), at the location of the target (accurate), or displaced up to 12 degrees from the target horizontally or vertically. RESULTS: Generally, displaced auditory cues reduced search times as compared with a condition in which the cue was uninformative. When the displacement was always along a single spatial dimension, the cue was as effective as a coincident cue if it was within the local visual area. However, when the dimension along which the cue was displaced varied randomly, the cue did not necessarily reduce search time and hurt performance when the visual search task was difficult. CONCLUSION: Designers of virtual audio displays should be aware that auditory cue accuracy will be affected by the difficulty of the visual task and the operators' knowledge of cue precision and reliability. APPLICATION: Findings from this study can be applied to the design of multimodal interfaces and augmented or virtual environments.     

Assisting people with visual impairments in aiming at a target on a large wall-mounted display

Large interactive displays have become ubiquitous in our everyday lives, but these displays are designed for the needs of sighted people. In this paper, we specifically address assisting people with visual impairments to aim at a target on a large wall-mounted display. We introduce a novel haptic device, which explores the use of vibrotactile feedback in blind user search strategies on a large wall-mounted display. Using mid-air gestures aided by vibrotactile feedback, we compared three target-aiming techniques: Random (baseline) and two novel techniques – Cruciform and Radial. The results of our two experiments show that visually impaired participants can find a target significantly faster with the Cruciform and Radial techniques than with the Random technique. In addition, they can retrieve information on a large display about twice as fast by augmenting speech feedback with haptic feedback in using the Radial technique. Although a large number of studies have been done on assistive interfaces for people who have visual impairments, very few studies have been done on large vertical display applications for them. In a broader sense, this work will be a stepping-stone for further research on interactive large public display technologies for users who are visually impaired.     

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.     

3‐D crosstalk and luminance uniformity from angular luminance profiles of multiview autostereoscopic 3‐D displays

Abstract— Autostereoscopic 3‐D display technologies enable a more immersive media experience by adding real depth to the visual content. However, the method used for the creation of a sensation of depth or stereo illusion contains several display design and content‐related issues that need to be carefully considered to maintain sufficient image quality. Conventionally, methods used for 3‐D image‐quality evaluations have been based on subjective testing. Optical measurements, in addition to subjective testing, can be used as an efficient tool for 3‐D display characterization. Objective characterization methods for autostereoscopic displays have been developed. How parameters affecting stereo image quality can be defined and measured, and how their effect on the stereo image quality can be evaluated have been investigated. Developed characterization methods are based on empirically gathered data. In this paper, previously presented methodology for two‐view displays is extended to cover autostereoscopic multiview displays. A distinction between displays where the change in content occurs in clear steps when the user moves in front of the display, and displays where the apparent movement of the objects is more continuous as a function of the head movement is made. Definitions for 3‐D luminance and luminance uniformity, which are equally important, as well as 3‐D crosstalk, which is the dominant factor in the evaluations of the perceived 3‐D image quality, is focused upon.     

Depth of focus and visual recognition of imagery presented on simultaneously viewed displays: implications for head-mounted displays

OBJECTIVE: We sought to determine the optimal focal distance for a semitransparent monocular head-mounted display (HMD) integrated with a flight simulator display and to investigate whether observers experienced visual discomfort or impaired target recognition when using an HMD set at the optimal distance. BACKGROUND: When an observer wears a monocular HMD and views a simulator display, focal distances of both displays must be within the observers' depth of focus to prevent blurred imagery. Because focal distance can vary by as much as 0.5 m in U.S. Air Force multifaceted simulator displays, we determined whether a monocular HMD could be integrated with a simulator display without blurred imagery or discomfort. METHOD: Depth of focus and visual recognition were measured with a staircase procedure, and visual discomfort was measured with a questionnaire. RESULTS: Depth of focus was 0.64 diopters in one condition tested, but it was affected by luminance level and display resolution. It was recommended that HMD focal distance equal the optical midpoint of the range of viewing distances encountered in the simulator. Moreover, wearing an HMD produced a decline in recognition performance for targets presented on the simulator display despite both displays being within observers' depth of focus and producing no visual discomfort. CONCLUSION: Monocular HMDs can be integrated with multifaceted simulator displays without blurred imagery or visual discomfort, provided that the correct focal distance is adopted. APPLICATION: For situations involving simultaneously viewed visual displays.     

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).     

Egocentric distance perception in large screen immersive displays

Many scientists have demonstrated that compared to the real world egocentric distances in head-mounted display virtual environments are underestimated. However, distance perception in large screen immersive displays has received less attention. We investigate egocentric distance perception in a virtual office room projected using a semi-spherical, a Max Planck Institute CyberMotion Simulator cabin and a flat large screen immersive display. The goal of our research is to systematically investigate distance perception in large screen immersive displays with commonly used technical specifications. We specifically investigate the role of distance to the target, stereoscopic projection and motion parallax on distance perception. We use verbal reports and blind walking as response measures for the real world experiment. Due to the limited space in the three large screen immersive displays we use only verbal reports as the response measure for the experiments in the virtual environment. Our results show an overall underestimation of distance perception in the large screen immersive displays, while verbal estimates of distances are nearly veridical in the real world. We find that even when providing motion parallax and stereoscopic depth cues to the observer in the flat large screen immersive display, participants estimate the distances to be smaller than intended. Although stereo cues in the flat large screen immersive display do increase distance estimates for the nearest distance, the impact of the stereoscopic depth cues is not enough to result in veridical distance perception. Further, we demonstrate that the distance to the target significantly influences the percent error of verbal estimates in both the real and virtual world. The impact of the distance to the target on the distance judgments is the same in the real world and in two of the used large screen displays, namely, the MPI CyberMotion Simulator cabin and the flat displays. However, in the semi-spherical display we observe a significantly different influence of distance to the target on verbal estimates of egocentric distances. Finally, we discuss potential reasons for our results. Based on the findings from our research we give general suggestions that could serve as methods for improving the LSIDs in terms of the accuracy of depth perception and suggest methods to compensate for the underestimation of verbal distance estimates in large screen immersive displays.     

Display size and distractor complexity effects on visual search

The proliferation of higher quality connected sensors is consistently increasing the amount of information available to operators, increasing the complexity of displayed information. Coupling this increase in information with larger, higher addressability displays may lead to increasingly complex visual search paradigms. The current research explored the effect of both display size and distractor symbol complexity on visual search efficiency across three different symbol set sizes. Overall, the results indicate a reduction in search efficiency as a function of both increased display size and distractor complexity, even for the high target densities employed within this study. Further, these variables can interact in target present conditions to influence search times.     

场景感知的分布式多智能体目标搜索方法

在视觉语义导航任务中,智能体通过视觉信息,寻找并导航到给定对象类别的目标处。然而,大部分现有的研究都是使用基于学习的框架来完成任务,这些研究在现实世界中应用的训练成本非常高,可移植性很低,并且它们只适用于单智能体,效率低下、容错能力差。为解决上述问题,本文提出一种基于场景感知的分布式多目标优化蒙特卡洛树搜索模型,该模型中多智能体实时在线规划并且不需要预先训练,利用场景感知先验知识结合观测信息实时对环境进行估计,并且利用改进的蒙特卡洛树搜索进行路径规划以此搜索目标。在Mtterport3D数据集中进行的实验表明,该模型在效率方面比单智能体有着显著的提高。     

Visual search of food nutrition labels

Using an eye-tracking methodology, we evaluated food nutrition labels' ability to support rapid and accurate visual search for nutrition information. Participants (5 practiced label readers and 5 nonreaders) viewed 180 trials of nutrition labels on a computer, finding answers to questions (e.g., serving size). Label manipulations included several alternative line arrangements, location of the question target item, and label size. Dependent measures included search time and number of fixations prior to visually capturing the target, as well as the accuracy and duration of the capturing fixation. Practiced label readers acquired the target more quickly and accurately than did less-practiced readers. Targets near the denser center of the label required 33% more time and were harder to find than targets at the top or bottom of the label. Thinner alignment lines were more influential than thicker anchoring lines on visual search time. Overall, the current nutrition label supported accurate and rapid search for desired information. Potential applications of the present methodology include the evaluation of warning labels and other static visual displays.     

Wide field of view compressive light field display using a multilayer architecture and tracked viewers

In this paper, we discuss an intuitive extension to compressive multilayer light field displays that greatly extends their field of view and depth of field. Rather than optimizing these displays to create a moderately narrow field of view at the center of the display, we constrain optimization to create narrow view cones that are directed to a few viewers' eyes, allowing the available display bandwidth to be utilized more efficiently. These narrow view cones follow the viewers, creating a wide apparent field of view. Imagery is also recalculated for the viewers' exact eye positions, creating a greater depth of field. The view cones can be scaled to match the positional error and latency of the tracking system. Using more efficient optimization and commodity tracking hardware and software, we demonstrate a real‐time, glasses‐free 3D display that offers a 100° × 40° field of view.     

Frames of reference for the display of battlefield information: judgment-display dependencies

In 2 experiments, U.S. Army soldiers viewed computer-generated displays that presented battlefield information from 3 different frames of reference: a 2D plan view display (with contour lines), a 3D exocentric perspective display, and an interactive 3D immersed display. In Experiment 1, soldiers made geographical judgments. The results suggested that both 3D displays suffered from ambiguity of distance estimates but that the 3D immersed display was most accurate for judging whether a location is directly visible from another. In Experiment 2, the 3D exocentric display was compared with a 3D immersed view, coupled with a small 2D inset map, in a more continuous battlefield scenario in which judgments of enemy activity were made. The findings of 3D ambiguity were replicated from Experiment 1. The accuracy of judgments of enemy activity suffered with the immersed display when information necessary to answer correctly did not appear in the initial forward view and required panning to acquire, reflecting the cognitive demands of integration across different views. This display also hindered soldiers' ability to report changes in enemy activity from one scene to the next. The results of this research will help to provide guidelines for the appropriate choice of computer display technology to assist in designing battlefield visualization aids. Caution should be exercised in choosing immersive viewpoints.     

Video 2‐D—to—3‐D conversion based on hybrid depth cueing

Abstract— With the maturation of three‐dimensional (3‐D) technologies, display systems can provide higher visual quality to enrich the viewer experience. However, the depth information required for 3‐D displays is not available in conventional 2‐D recorded contents. Therefore, the conversion of existing 2‐D video to 3‐D video becomes an important issue for emerging 3‐D applications. This paper presents a system which automatically converts 2‐D videos to 3‐D format. The proposed system combines three major depth cues: the depth from motion, the scene depth from geometrical perspective, and the fine‐granularity depth from the relative position. The proposed system uses a block‐based method incorporating a joint bilateral filter to efficiently generate visually comfortable depth maps and to diminish the blocky artifacts. By means of the generated depth map, 2‐D videos can be readily converted into 3‐D format. Moreover, for conventional 2‐D displays, a 2‐D image/video depth perception enhancement application is also presented. With the depth‐aware adjustment of color saturation, contrast, and edge, the stereo effect of the 2‐D content can be enhanced. A user study on subjective quality shows that the proposed method has promising results on depth quality and visual comfort.     

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.     

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     

Aurally aided visual search in three-dimensional space

We conducted an experiment to evaluate the effectiveness of spatial audio displays on target acquisition performance. Participants performed a visual search task with and without the aid of a spatial audio display. Potential target locations ranged between plus and minus 180 degrees in azimuth and from -70 degrees to +90 degrees in elevation. Independent variables included the number of visual distractors present (1, 5, 10, 25, 50) and the spatial audio condition (no spatial audio, free-field spatial audio, virtual spatial audio). Results indicated that both free-field and virtual audio cues engendered a significant decrease in search times. Potential applications of this research include the design of spatial audio displays for aircraft cockpits and ground combat vehicles.