Visual and memory search in complex environments: determinants of eye movements and search performance

Previous research on visual and memory search revealed various top down and bottom up factors influencing performance. However, utilising abstract stimuli (e.g. geometrical shapes or letters) and focussing on individual factors has often limited the applicability of research findings. Two experiments were designed to analyse which attributes of a product facilitate search in an applied environment. Participants scanned displays containing juice packages while their eye movements were recorded. The familiarity, saliency, and position of search targets were systematically varied. Experiment 1 involved a visual search task, whereas Experiment 2 focussed on memory search. The results showed that bottom up (target saliency) and top down (target familiarity) factors strongly interacted. Overt visual attention was influenced by cultural habits, purposes, and current task demands. The results provide a solid database for assessing the impact and interplay of fundamental top down and bottom up determinants of search processes in applied fields of psychology. Practitioner Summary: Our study demonstrates how a product (or a visual item in general) needs to be designed and placed to ensure that it can be found effectively and efficiently within complex environments. Corresponding product design should result in faster and more accurate visual and memory based search processes.     

Effects of discomfort glare on performance in attending peripheral visual information in displays

Large screens have become more popular in recent years. Because of the increasing size of displays, the amount of information presented in the peripheral visual field has gained importance in many tasks on visual display units. Users of displays are often exposed to some change or difference in luminance in or between different areas of a display, which in turn may produce a phenomenon known as discomfort glare. Discomfort glare is likely to affect cognitive performance. The performance in the visual periphery is more susceptible to disturbances as is the case for the performance in the central visual field.     

Effects of display format and colour coding schemes on visual monitoring performance using spatially and temporally distributed visual displays

The present study examined factors that decreased task complexity so that a technology which temporally, rather than spatially, distributed information (i.e. RAP COM, for rapid communication) would result in performace advantages. This was accomplished by physically integrating the stimulus information into either the display format (i.e. an analog format) or into the response coding scheme (i.e. a colour coding scheme). Performance using the RAP COM display indicated a lower proportion of errors for the analog than for the digital format; however, a longer mean response time for a correct response was found for the analog than for the digital format. Two colour coding response schemes were used: (a)_a continuous scheme that comparised gradual changes between red and blue; (b) a distinctive scheme consisting of the colours cyan, green, yellow, orange, red, mauve, purple and blue. When the continuous colour coding responses scheme was used, performance using the RAP COM display, as compared with the spatial display, was no different after extended practice. The results of these experiments taken together indicate that the RAP COM display type may be a viable technology for some limited ‘real world’ environments.     

The effects of wearing respirators on human fine motor,visual, and cognitive performance

When selecting a respirator, it is important to understand how employees' motor, visual and cognitive abilities are impacted by the personal protective equipment. This study compares dust, powered-air-purifying and full-face, negative-pressure respirators. Thirty participants performed three varied tasks. Each participant performed each task without a respirator and while wearing the three respirator types. The tasks included a hand tool dexterity test, the Motor-Free Visual Perception Test and the Serial Sevens Test to evaluate fine motor, visual and cognitive performance, respectively. The time required for task completion and the errors made were measured. Analysis showed no significant effect due to respirator use on the task completion time. A significant increase was found in the error rate when participants performed the cognitive test wearing the full-face, negative-pressure respirator. Participants had varying respirator preferences. They indicated a potential for full-face, negative-pressure respirators to negatively affect jobs demanding high cognitive skills such as problem solving and decision-making.

Practitioner summary: while respirators are life-saving personal protective equipment (PPE), they can unintentionally reduce human performance, especially if job characteristics are not considered during PPE selection. An experiment was conducted to compare three respirators (dust respirator, powered-air-purifying respirators and full-face respirator) for varying task types. The full-face respirator was found to affect human cognitive performance negatively.     

Evaluating the Impact of the Communication System on Distributed Virtual Environments

This paper analyzes the impact of the communication system on distributed virtual environments. We present a platform model that express the communication requirements of this kind of applications and evaluate it via simulation. Performance measurements varied the number of participants, the partition of the virtual environment, a participant's speed, and the size of the virtual world. Results show that the division of the environment improves the delay both to enter and to exchange groups, and reduces the number of messages exchanged. This partition allows both a participant's speed and the number of participants to increase, thereby ensuring a good interactivity.     

Effects of computer icons and figure/background area ratios and color combinations on visual search performance on an LCD monitor

This study investigated the effects of figure/background color combinations, the type of computer icon and the figure/background area ratio on visual search performance on a liquid crystal display (LCD) screen. Participants had to search for the target item in a circle stimulus array, which had a diameter of 20 cm and included one target and 19 distracters. Results showed that these three independent variables significantly affected the visual search performance. The search times for EMAIL and SAVE computer icons were significantly shorter than that for a PRINT computer icon. Visual search performance was better for computer icons with a 90% figure/background area ratio than for a 70% ratio. However, no difference in search time between 90% and 50% ratios or between 70% and 50% ratios was observed. Color combinations also significantly affected the visual search performance and white/yellow and white/blue color combinations for the figure/background resulted in better performance than black/blue and black/yellow combinations. However, no difference in search time was observed for participants with and without esthetic training. The implications of the results are applicable to design icons for the interfacing of computers and communication information.     

The effect of text and background colour on visual search of Web pages

Usability and visual impact in Web pages are not necessarily compatible ideals. This paper investigates the effect of colour on the presentation of information in a navigation bar, and aims to contribute towards design guidelines for the use of colour on the Web. We studied the effect of the combination of text and background colour on visual search performance and subjective preference. Twenty-nine participants carried out a visual search task using mock Web pages. Analysis showed that higher contrasts between text and background colour led to faster searching and were rated more favourably. The results are discussed in terms of visual search processes and design recommendations are given.     

Effects of display modality on critical battlefield e-map search performance

Visual search performance in visual display terminals can be affected by several changeable display parameters, such as the dimensions of screen, target size and background clutter. We found that when there was time pressure for operators to execute the critical battlefield map searching in a control room, efficient visual search became more important. We investigated the visual search performance in a simulated radar interface, which included the warrior symbology. Thirty-six participants were recruited and a three-factor mixed design was used in which the independent variables were three screen dimensions (7, 15 and 21 in.), five icon sizes (visual angle 40, 50, 60, 70 and 80 min of arc) and two map background clutter types (topography displayed [TD] and topography not displayed [TND]). The five dependent variables were completion time, accuracy, fixation duration, fixation count and saccade amplitude. The results showed that the best icon sizes were 80 and 70 min. The 21 in. screen dimension was chosen as the superior screen for search tasks. The TND map background with less clutters produced higher accuracy compared to that of TD background with clutter. The results of this research can be used in control room design to promote operators’ visual search performance.     

The degree of human visual attention in the visual search

Human beings can obtain visual information in parallel through the retina, but they cannot pay attention to all the information at the same time. In psychological studies, the human characteristics of visual attention have often been investigated by analyzing the characteristics of the visual search task. Previous studies suggested that the information features of the visual search task are processed in parallel at early stages of processing. However, the authors consider that these features are not processed completely in parallel, and have a reciprocal action to each other. In order to clarify the reciprocal action of the features in a visual search and the continuity of visual attention, the characteristics of reaction times were measured with changing forms of visual stimuli. The experimental results suggested that the reaction time changed when the features of the visual stimuli in the visual search task changed. This means that the features are affected by each other. Furthermore, continuity of reciprocal action is also suggested, and the degree of visual attention is decided by this continuity. The results provided significant basic data to support our proposed mathematical model of visual attention. This work was presented, in part, at the Fourth International Symposium on Artificial Life and Robotics, Oita, Japan, January 19–22, 1999     

基于Internet的可视化协同设计系统的研究与应用

协同虚拟环境是计算机支持的协同工作与虚拟现实相结合的产物,它使协同工作的人们能以最自然的方式进行合作成为了可能。利用现有普通的Internet软硬件条件,提出了一个运行于Internet上的基于协同虚拟环境的技术方案,结合了VRML与JAVA各自的技术特点,构建了以虚拟现实为交互手段的协同工作系统,来支持人们跨Internet的、基于图解思考的可视化协同分析与设计工作。     

一种基于指纹和可视可擦除水印的安全广播视频分发方案

提出了一种基于可视可擦除水印和数字指纹的多媒体安全分发方案.利用可视水印提供预览视频,支持用户获得授权后的可视水印擦除,伴随擦除过程同时完成用户指纹的嵌入.     

Analysis of visual acuity and motion resolvability as measures for optimal visual perception of the workspace

For working tasks with high visual demand, ergonomic design of the working stations requires defining criteria for comparative evaluation and analysis of the visual perceptibility in different regions of the workspace. This paper provides kinematic models of visual acuity and motion resolvability as adopted measures of visual perceptibility of the workspace. The proposed models have been examined through two sets of experiments. The first experiment is designed to compare the models outputs with those from experiments. Time measurements of the participants’ response to visual events are employed for calculation of the perceptibility measures. The overall comparison results show similar patterns and moderate statistical errors of the measured and kinematically modeled values of the parameters. In the second experiment, the proposed set of visual perceptibility measures are examined for a simulated industrial task of inserting electronic chips into slots of a working table, resembling a fine assembly line of transponders manufacturing. The results from ANOVA tests for the visual acuity and the motion resolvability justify the postures adopted by the participants using visual perceptibility measures for completing the insertion tasks.     

Impact of parallax and interpupillary distance on size judgment performances of virtual objects in stereoscopic displays

Effective interactions in both real and stereoscopic environments require accurate perceptions of size and position. This study investigated the effects of parallax and interpupillary distance (IPD) on size perception of virtual objects in widescreen stereoscopic environments. Twelve participants viewed virtual spherical targets displayed at seven different depth positions, based on seven parallax levels. A perceptual matching task using five circular plates of different sizes was used to report the size judgment. The results indicated that the virtual objects were perceived as larger and smaller than the corresponding theoretical sizes, respectively, in negative and positive parallaxes. Similarly, the estimates from participants with small IPDs were greater than the predicted estimates. The findings of this study are used to explain human factor issues such as the phenomenon of inaccurate depth judgments in virtual environments, where compression is widely reported, especially at farther egocentric distances. Furthermore, a multiple regression model was developed to describe how the size was affected by parallax and IPD.

Practitioner Summary: The study investigates the effects of parallax and interpupillary distance on size perception of virtual targets in a stereoscopic environment. Virtual objects were perceived as larger in negative and smaller in positive parallax. Also, size estimates were greater than the theoretical sizes for participants with smaller IPD. A multiple-regression model explains the impact of parallax and measured IPD. Abbreviations IPD interpupillary distance

VR virtual eality

HMD head mounted-displays

2AFC two-alternative forced choice

IOD interocular distance

PD pupillary distance

ANOVA analysis of variance

     

Task and user effects on reading patterns in information search

We report on an investigation into people’s behaviors on information search tasks, specifically the relation between eye movement patterns and task characteristics. We conducted two independent user studies (n = 32 and n = 40), one with journalism tasks and the other with genomics tasks. The tasks were constructed to represent information needs of these two different users groups and to vary in several dimensions according to a task classification scheme. For each participant we classified eye gaze data to construct models of their reading patterns. The reading models were analyzed with respect to the effect of task types and Web page types on reading eye movement patterns. We report on relationships between tasks and individual reading behaviors at the task and page level. Specifically we show that transitions between scanning and reading behavior in eye movement patterns and the amount of text processed may be an implicit indicator of the current task type facets. This may be useful in building user and task models that can be useful in personalization of information systems and so address design demands driven by increasingly complex user actions with information systems. One of the contributions of this research is a new methodology to model information search behavior and investigate information acquisition and cognitive processing in interactive information tasks.     

The effect of VDU colour on visual fatigue in the fovea and periphery of the visual field

The effect of the display of a visual display unit (VDU) on visual fatigue was investigated using the critical flicker frequency (CFF) paradigm. The results indicate that fatigue, as measured by CFF, varied as the VDU colour and eccentricity changed in the visual field. It was found that blue and red, that is, both extremes of the visible spectrum, strongly caused visual fatigue in the visual field when compared to green and yellow, that is, the middle range of the visible spectrum. Furthermore, for yellow and blue, VDU signal fatigue tended to decrease as the distance from the fovea increased. whereas for red and green, it increased by up to 10° in the periphery and then tended to decrease. The results indicate that yellow and green cause less fatigue in the periphery and fovea, respectively.     

Effect of button location on driver's visual behaviour and safety perception

Although buttons are a frequently used type of control in car interiors, little research has been undertaken on how the usage of buttons affects the visual behaviour of the driver. In this study, the aim was to analyse the effect of push button location and auditory feedback on drivers' visual time off road and safety perception when driving in a real traffic situation. The effect of six button locations (five on the centre stack, one near the gear stick) was tested. Drivers' visual behaviour was studied in real traffic on a motorway. An eye tracking system recorded the visual behaviour of eight drivers who, in 96 repeated trials each, were instructed to press a specific button. Data analysis focused on the drivers' visual time off road and safety perception in relation to the location of the button to be pressed. Auditory feedback did not show a significant effect on visual time off road. The time off road increased significantly as the angle increased between the normal line of sight and button location for the five buttons placed on the centre stack. Results for the button located close to the gear stick, with the highest eccentricity, produced a short time off road. This unexpected finding is discussed in terms of three potential explanations: 1) the role of perceptual discrimination; 2) risk perception; and 3) motor control.     

The impact of online video lecture recordings and automated feedback on student performance

To what extent a blended learning configuration of face-to-face lectures, online on-demand video recordings of the face-to-face lectures and the offering of online quizzes with appropriate feedback has an additional positive impact on the performance of these students compared to the traditional face-to-face course approach? In a between-subjects design in which students were randomly assigned to a group having access to the online lectures including multiple choice quizzes and appropriate feedback or to a group having access to the online lectures only, 474 students (161 men and 313 women) of a course on European Law agreed to participate in the experiment. By using regression analysis we found that the course grade of the students was predicted by their grade point average, their study discipline, their grade goal for the course, the expected difficulty-level of the course, the number of online lectures they viewed, the number of lectures the students attended in person and the interaction between the lectures they viewed online and attended in person. Students who attended few lectures had more benefit from viewing online lectures than students who attended many lectures. In contrast to our expectations, the regression analysis did not show a significant effect of automated feedback on student performance. Offering recordings of face-to-face lectures is an easy extension of a traditional course and is of practical importance, because it enables students who are often absent from the regular face-to-face lectures to be able to improve their course grade by viewing the lectures online.     

Effects of menu structure and touch screen scrolling style on the variability of glance durations during in-vehicle visual search tasks

The effects of alternative navigation device display features on drivers' visual sampling efficiency while searching forpoints of interest were studied in two driving simulation experiments with 40 participants. Given that the number of display items was sufficient, display features that facilitate resumption of visual search following interruptions were expected to lead to more consistent in-vehicle glance durations. As predicted, compared with a grid-style menu, searching information in a list-style menu while driving led to smaller variance in durations of in-vehicle glances, in particular with nine item displays. Kinetic touch screen scrolling induced a greater number of very short in-vehicle glances than scrolling with arrow buttons. The touch screen functionality did not significantly diminish the negative effects of the grid-menu compared with physical controls with list-style menus. The findings suggest that resumability of self-paced, in-vehicle visual search tasks could be assessed with the measures of variance of in-vehicle glance duration distributions.

Statement of Relevance: The reported research reveals display design factors affecting safety-relevant variability of in-vehicle glance durations and provides a theoretical framework for explaining the effects. The research can have a significant methodical value for driver distraction research and practical value for the design and testing of in-vehicle user interfaces.     

Combining experiences of race gaming and natural driving affects gaze location strategy in simulated context

Abstract

The aims of the study were to investigate the effects of race gaming experience in playing racing video games on gaze behaviour and performance of drivers and the effects of natural driving experience on gaze behaviour and performance of gamers. Thirty participants, divided into drivers-gamers, drivers-non-gamers and non-drivers-gamers, were asked to drive in a race circuit as fast as possible while their eye movements were recorded. Drivers-gamers spent more time looking at the lane than non-drivers-gamers. Furthermore, drivers-gamers performed greater number of fixations towards the speedometer and showed faster performance in the racing task than the drivers-non-gamers. Combining natural driving and race gaming experiences changed the gaze location strategy of drivers.

Practitioner summary: Racing video games practitioners have high propensity to exhibit attitudes and intentions of risky driving behaviour. Combining natural driving and race gaming experiences affects gaze behaviour strategy of drivers.

Abbreviations: DG: Drivers-gamers; DNG: Drivers-non-gamers; NDG: Non-drivers-gamers; AOIs: Areas of Interest; r-NUMFIX: Relative number of fixations; r-DURFIX: Relative fixations duration