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This session looks to serve the purpose of recalling and recounting the life and contributions of Professor John Senders. The contributors to this session include his direct colleagues, his students, his co-authors, those whom he inspired, and even members of his family. These designations are not exclusive! Senders made so many contributions across virtually a century of his lifetime that we are constrained to provide only selective highlights in this memorial session, such as John being named the winner of an “Ig-Nobel” Award. We shall each survey particular works which influenced us, but interweave those observations with personal experiences that can serve to reveal John the character, who was so much more than the simple written record that he has left behind.

A method is proposed for evaluating participants’ performance in a global spatial awareness task involving identification of complex winding routes. Rather than using coarse measures of spatial error, the method of paired comparisons employs impartial judges to compare sets of aggregated experimental data generated by the participants with respect closeness in shape to the target route. The method was applied to a set of data in an experimental investigation of the effect of height on a participant’s ability to identify the route he had just flown over (in a 20 second video). Seven participants performed a total of 48 trials in a 4 (heights) X 2 (trial blocks) within-subjects experiment. Results from the paired comparison analysis suggested that height had a statistically significant effect on correct route identification. Of equal importance in the context of the present paper, the method of paired comparison analysis proved to be effective in quantifying performance data that did not otherwise lend themselves to conventional methods of quantification.

Research using self-paced visual occlusion has traditionally analysed mean occlusion times, thereby neglecting potential insights to be gained from variability across individual visual sampling decisions. This paper proposes a framework for analysing visual occlusion data based on a hierarchy of sampling strategies. The framework describes each sampling decision as being dependent on both system characteristics (mean performance) and information available during sampling (variability). To illustrate the framework, data from an on-road study were analysed. Self-paced occlusion times were shown to fit a descriptive function both for lane deviations observed at the end of previous visual samples and for predicted lane deviations at the end of occlusion intervals. The fact that the latter fit was better suggests that participants, especially the more experienced ones, were indeed able to use predictions in their sampling decisions.

Little empirical evidence can be found in the visual occlusion literature to justify decisions about how glance durations should be fixed for self-paced visual occlusion investigations. This paper presents a hypothesis about how glance duration may affect performance, based on a theory of how uncertainty develops as an operator's vision is occluded and how it is resolved during visual glances. Data are analysed from two on-road driving experiments involving a range of fixed glance durations. The analysis is repeated with data collected from an analogous study in a low fidelity driving simulator. Both analyses support the hypothesis that increasing glance duration may prolong achievable mean occlusion times, but only up to a certain point, after which essentially no changes are expected. The paper concludes with a practical recommendation for selecting fixed glance durations for (self-paced) visual occlusion studies. Language: en

Ultrasound-guided nerve block (UGNB) allows anesthesiologists to perform regional anesthesia around peripheral nerves using ultrasound images for visual guidance. Compared to conventional peripheral nerve stimulation techniques, UGNB provides a safer and more effective method to perform regional anesthesia. However, identification of peripheral nerves with ultrasound can often be problematic, especially for inexperienced users. This paper provides an in depth analysis of the difficulties associated with targeting and locating peripheral nerves during UGNB and proposes a real-time image processing solution, in the form of a low-pass persistence filter, which should increase target saliency in ultrasound images.

This study investigates the potential benefits of a novel image processing filter, based on introducing persistence to an image to increase visual sensitivity for ultrasound-guided nerve block procedures. The effectiveness of the filter was examined for multiple levels of target velocity and filter persistence, using simulated ultrasound-like images. Subjects were asked to detect a covert target in twelve experimental conditions. The experimental results show that the persistence filter augments the target's saliency and consequently contributes to an effective increase in visual sensitivity. In addition, the results show that the filter is most effective for mid-range target velocities combined with high levels of visual persistence. The study concludes that the filter has the potential to improve present ultrasound-guided nerve block procedures and provides recommendations for implementing the filter in real-world settings.

In this paper, we introduce an innovative conflict detection and resolution display for air traffic control. Our display explicitly incorporates uncertainties in velocity, heading, and position of each airplane in a given air space. Probabilistic, temporal, and spatial information of potential conflicts is provided through integrated graphical patterns.

The difficulties in performing manual control tasks under visual-motor mismatch are well documented. For example, laparoscopic surgeons must operate in an environment where a motor movement and the visual feedback of that same movement are ordinarily misaligned with respect to each other, increasing the risk of control errors. To complement conventional global measures of motor performance, which provide insight into spatial and/or temporal performance averaged over several trials, a bivariate dynamic measure encompassing joint time and space components is proposed. These two components are the instantaneous velocity and movement efficiency, derived from recorded movement trajectories. The dynamic measure consists of a graphical representation of the bivariate data, in conjunction with a non-parametric statistical analysis. An example is given of the dynamic measure applied to movement trajectories from an investigation involving simulated laparoscopic pointing under visual-motor mismatch. Results from both global and dynamic measures are discussed, along with limitations of the multivariate dynamic measure.

This paper reports on an investigation of how manipulation of optical looming cues can influence braking behaviour, for automobile driving in a low-fidelity simulator. Twenty participants were instructed to follow a leading vehicle (LV) and appropriately respond to braking events of the LV, which occurred randomly and at different deceleration rates. During some braking events, the size of the LV was manipulated in different ways, without subjects being aware, in a manner concordant with the optical expansion that would have been observed during braking if the LV had been displaced to be closer or further away. Results showed that subjects braked sooner when confronting an expanding LV and later for a contracting LV, relative to a constant-size LV, to an extent corresponding to the magnitude of the manipulation. The experiment supports the theory that drivers use TTC information derived from optic looming to control braking.

A potential application of optical looming manipulation is investigated: a dynamic brake light concept for potentially reducing the frequency of rear-end collisions in automobile driving. In a low-fidelity driving simulator, forty participants were instructed to follow a leading vehicle (LV) and appropriately respond to braking of the LV, under three visibility conditions: day, night-time with headlights, and night-time without headlights. During some LV braking events, separation and size of the brake lights of the LV were imperceptibly expanded or contracted, at one of two levels, to simulate an effective virtual time shift in the headway of the LV. Results show that this concept was effective only for very poor visibility conditions: at night with no headlights, for which LV brake lights were most salient. Subjects generally braked sooner when confronting a LV with expanding brake lights, and later for contracting lights, in comparison with the no manipulation case.

Optical looming has been proposed as a potentially important cue for the perception of time-to-collision (TTC) in the control of locomotion. In this paper, an investigation is reported on how manipulation of the optical looming cue can influence the perception of TTC, and thereby braking behaviour, for automobile driving in a low fidelity simulator. Eleven participants were instructed to follow a leading vehicle (LV) and appropriately respond to the braking events of the LV, which occurred randomly at different deceleration rates. For some braking events, during braking of the LV, size of the LV was expanded without subjects being aware of it. Results showed that subjects braked sooner when confronting an expanding LV compared to a constant-size LV. The experiment supports the theory that drivers use TTC information derived from optic looming to control braking. Potential application of the results to possibly reduce occurrences of rear-end collisions in real automobile driving is also discussed.

Direct manipulation of optical looming provides convincing evidence of the contribution of optical looming in estimating time-to-collision (TTC). Precise manipulation of optical looming cues can be easily accomplished through computational scaling of (real or virtual) objects without impinging upon the naturalness of the task. This paper first discusses three ways to manipulate optical looming by scaling object size in order to influence perception of TTC. Then two principles affecting the implementation of optical looming manipulation are addressed. Next by revisiting the data of previous research, influences of knowledge about the optical looming manipulation and practice on the effect of optical looming manipulation are discussed. This supports our proposed principles and confirms the possibility of introducing the concept of optical looming manipulation into actual automobile design. Finally a potential application of optical looming manipulation, a dynamic brake light system, is proposed for automobile driving, to reduce the frequency of rear-end collisions. Issues in implementation of such a system and future research to validate it are also identified.

Physicians need to integrate large amounts of information from patient records to determine their patients' current status. Retrieving and querying patient related information involves cognitive processes. To design an easy to use and effective querying interface for modern electronic medical records, a good understanding of the cognitive processes involved in patient related information querying is essential. In this paper cognitive work analysis (CWA) is discussed as a tool for understanding the work domain and for guiding the development of new electronic patient record interfaces, in our case for use by rheumatologists. In particular, CWA is discussed from the point of view of the abstraction hierarchy (AH) framework, and an initial AH of the patient information system work domain is presented.

Much research has been carried out on providing navigational aids and improving users' wayfinding ability across a variety of navigation related tasks. In this study, we focus on investigating users' navigational performance with respect to the display frame of reference in a large scale virtual environment. Dynamic viewpoint tethering is proposed as a means to improve user control and reduce the need for mental rotations, thus facilitating the acquisition of configurational knowledge about the virtual space. The modelling of dynamic viewpoint tethering is explained and recent research findings are presented. Twelve volunteers participated in an experiment in which they were instructed to control an aircraft-shaped cursor flying through a set of virtual tunnels (local guidance) and to answer questions about the environment (global awareness). Experimental results showed that neither the very loose dynamic tether nor the completely rigid tether supported the best control performance. Rather, an optimal tether configuration lies at the centre of the rigidity continuum. Research results are discussed from the point of view of design of navigational system interfaces.

Viewpoint tethering, as a way of integrating information from both egocentric and exocentric frames of reference, has been proposed as a means of supporting efficient navigation in virtual environments. In this paper, we report our latest findings on the effects of tether length on navigational performance. Twelve volunteers participated in an experiment in which they were instructed to control an aircraft-shaped cursor flying through a set of virtual tunnels and to answer questions about the environment. Experimental results showed that: (1) subjects' global awareness performance improved with an increase of tether length; and (2) neither the short tether nor the long tether supported the best local guidance performance. Rather, the best performance was observed for an intermediate length tethered display. The existence of an optimal value for this parameter provides useful guidelines for the design of navigational system interfaces.

Numerous automated systems are currently in use to assist controllers during air and naval traffic management. However, inferring the future intentions and courses of numerous aircraft or ships at various points in time remains problematic due to a variety of control disturbances. In this paper, a new graphical display concept was evaluated. This display concept provides predictive information about the time, location, and probability of potential traffic conflicts in the form of topological contour displays that were superimposed onto conventional traffic information. Performances on two formats of the new graphical display were compared to a conventional display that does not present predictive traffic information. Participants in the study engaged in a ship control collision avoidance task by performing a series of ship manoeuvres to minimize the danger levels of potential collisions. Although the results of the study are pending, it is hypothesized that the new graphical displays will assist participants in making improved manoeuvring decisions to avoid potential conflicts compared to the conventional display.

A sensitivity study involving a real-virtual object alignment task was performed in a stereoscopic augmented reality environment, in which the known conflict between binocular fusion and object interposition cues was expected to play a major role. The object was to evaluate subjects' sensitivity to visual texture of a real hemisphere surface and to target position at designated probe points on that surface. Consistent with earlier experiments, the results indicate that: a) both surface texture and target position had significant effects both on real-virtual object alignment and on the estimate of surface normal direction; b) fusion breakdown caused by the conflict between occlusion and binocular disparity could have been used as an extra depth cue to detect virtual and real object interactions. In addition, a practical solution to improving remote 3D measurement accuracy is proposed.

In a rotated visual-motor mapping environment, human spatial performance is seriously affected by misaligned visual and motor reference axes, resulting in elevated spatial errors. In this paper, we propose a history trail display in an augmented reality setting. We investigate the effectiveness of the display in consecutive aiming tasks, under normal visual-motor mapping, as well as mappings with 90°, 135°, and 180° rotations. Spatial movement error and the smoothness of the trajectories were measured and compared between the history trail display and the regular video display. Our results show that, under normal mapping condition, the history trail appears to help reduce the spatial movement error and improve the smoothness of the movement trajectories. With rotated mappings, the benefit of the history trail becomes significant only after a certain degree of adaptation to the rotated mappings has been attained. The history trail appears to enhance the perception of errors, movement direction, and speed information for error-correcting processes during the aiming movements.

Dynamic viewpoint tethering is an innovative display technique which has been proposed to support effective navigation in large-scale virtual environments, by integrating information from different frames of reference. In this paper, we explain the modelling of a dynamic tether and report our latest research findings in investigating the optimal parametric values of tether configuration and their relations to human users' navigational performance. Tethered displays with different parametric configurations were compared. Participants were instructed to control an aircraft-shaped cursor flying in a virtual tunnel and to answer questions about the environment. The results revealed that critically damped tethers supported the best local guidance performance. No significant global awareness performance differences were observed under all display conditions.

This paper summarises the results of two laboratory studies conducted to explore the potential benefits of hyperstereoscopic video for aerial search and rescue (SAR). The studies were conducted using a single camera hyperstereoscopic video system (designed for aerial SAR) as the test platform. The first study was designed to evaluate potential benefits of hyperstereopsis provided by large viewpoint separation. It was found that individual differences play an important role in defining a possible “optimal” viewpoint separation for the system. The second study was conducted to test the effect of increased viewpoint separation on tolerance of vertical disparity. The results corroborated expectations that increased viewpoint separation would reduce vertical disparity tolerance. Guidelines are given for future modifications and system implementation.

Misalignments between display and control reference frames complicate execution of many remote control tasks by loading the operator's attentional resources with mental transformations. It is thus important to maintain alignment between an operator's controls and her view of the controlled object or task space. Maximising the operator's situational awareness within this task space by providing an optimal frame of reference also simplifies task execution. Traditional rigid tethering integrates desirable egocentric and exocentric aspects of a display by connecting an exocentric view of the task space to the system being controlled. This paper introduces the concept of dynamic tethering (a superset of rigid tethering) which also preserves the principle of the moving part while maintaining control-display motion compatibility. Two experiments are presented, which show that compliance with these principles decreases the frequency of control reversals, improves reaction times, and decreases the RMS error associated with tracking performance.

Navigating through minimal access surgical environments such as the human colon can be difficult, even for expert gastroenterologists. “Getting lost” is a common experience for endoscopists, especially within the tortuous sigmoid colon where salient landmarks are not generally available. This paper presents the concept of “getting lost” in endoscoppy as a loss of both global and local spatial orientation. For the endoscopist performing a colonoscopy, the consequence of local disorientation is an inability to continue the procedure, or possibly even injury to the patient, while consequences of global disorientation can be mistaking the location of a lesion, and/or incomplete examination, resulting in misdiagnosis. This study provides important insights into the physical and cognitive constraints of the task of navigating in colonoscopy, contributing to disorientation in the colon. The implications of our findings for the design of navigational aids and training tools are also discussed.

The primary objective of this simulator study was to examine how attentional demand during automobile driving changes as a function of vehicle speed, road curvature and lane width. Attentional demand was estimated quantitatively using self-paced visual occlusion during driving and was calculated as the percent of the time that the visual occlusion spectacles were open. The results revealed that, in accordance with earlier related studies in the literature, attentional demand increases as speed increases and as lane width decreases, and is also greater for curved as compared to straight road segments. Implications of the findings both for further research and practical road design are discussed.

The Head Mounted Display (HMD) is discussed as a subset of Mixed Reality (MR) displays. A definition of MR is given, in terms of image mixtures along a Reality-Virtuality (RV) Continuum, including the subclasses of augmented reality (AR) and augmented virtuality (AV). In relation to actual task execution, the relative need for local guidance information versus more global planning and navigational information is discussed. A taxonomic framework for classifying MR systems is presented, in terms of not only the RV continuum, but also the degree of centricity of the observer relative to a nominal viewpoint and the extent of control-display congruence. Several practical examples of MR systems are presented, all from the domain of surgery, and for each a volume within the MR design space is proposed.

This paper presents a method for structuring the work domain of the anesthesiologist in the operating room, using Rasmussen's (1986) approach for work domain analysis. The goal of this research is to provide an integrated approach for patient monitoring by bridging the gap between physiological principles associated with the patient and clinical practice. Data were collected from literature reviews, discussions with anesthesiologists, operating room observations, and simulator sessions to develop the work domain representation. From this information, the work domain was structured using various levels of abstraction and decomposition, independent of any particular situation. Next, an analysis of the links between the operating room and the work domain was performed. The results indicated that this approach has useful insights for training and interface design. The approach provided a framework for representing the work domain as an invariant purpose-based structure for a constantly changing work environment.

The concept of Augmented Reality (AR) displays is defined, in relation to the amount of real (unmodelled) and virtual (modelled) data presented in an image, as those displays in which real images, such as video, are enhanced with computer generated graphics. For the important class of stereoscopic AR displays, several factors may cause potential perceptual ambiguities, however, which manifest themselves in terms of decreased accuracy and precision whenever virtual objects must be aligned with real ones. A review is given of research conducted to assess both the magnitude of these perceptual effects and the effectiveness of a computer assisted Virtual Tape Measure (VTM), which has been developed for performing quantitative 3D measurements on real-world stereo images.

A unique measuring tool, the Virtual Tape Measure (VTM), was developed in prototype form to minimize the inaccuracy surgeons encounter when trying to estimate the measurement of structures seen under the operating microscope. Superimposed on a stereo-video image of the surgical field taken through an operating microscope, the VTM is a three-dimensional measuring tool comprising a stereo-computer graphic pointer and a tethering line. The human operator simply places the VTM pointer adjacent two points he wishes to measure on the stereo-video image by controlling a three degrees of freedom (x, y, z-axes) input device. Active liquid shutter glasses must be worn to visualize the pointer and video images in stereo. To test the accuracy of the system, seven subjects used the VTM to measure distances between two dot models placed under the operating microscope. The absolute distance between the two dots ranged from 4 mm to 27 mm in a field of view measuring 20 mm × 30 mm. The distance in depth between the two dots ranged from 0 mm to 19 mm. Overall bias was an overestimation of 0.3 mm with a 95% confidence interval of 0.1 mm to 0.5 mm. The overall precision, as defined by variance of the error was 0.4 mm with a 95% confidence interval of 0.3 to 0.6 mm. Testing shows the VTM prototype system to be an accurate and reliable tool for measuring small objects with size scales typically encountered under the operating microscope during surgical procedures.

Case rounds are a prominent and important means of training in medical domains. As part of a field study of anesthesiologists’ problem solving activities, we audiotaped the discussion of 10 cases spreading over 4 case rounds. This paper describes the method used in data collection and analysis, followed by the major findings of the study. The study identified three types of skills transferred in case rounds: procedural knowledge, sensitivity to precursors of potential problems, and the ability to prepare for contingencies. The study also showed the potential of case rounds in studying cognitive activities in naturalistic settings.

This paper reports on asymmetrical spatial accuracy of human subjects in tracking of an object which moves randomly with 6 degrees-of-freedom (DOF) in a 3D environment. It was found that, for translational errors, RMS deviations in the depth (Z) direction were 40% higher than those in the horizontal (X) direction, for an experimental display which provided binocular disparity (stereopsis), perspective and partial occlusion cues. In general, translational tracking errors in the vertical (Y) direction were greater than those in the X direction and smaller than those in the Z direction. In early stages of practice, vertical errors were similar to those in the Z direction, but as learning progressed, errors in the X and Y dimensions converged. These finding were consistent across two types of controllers and different tracking paths in the 3D environment. It would appear that horizontal movement requires higher attentional resource priority over vertical movement in such a tracking task.

Previous studies in complex domains such as power plants and air traffic control have described a wide range of behaviours not addressed by traditional psychological studies. This led to a field study of problem solving in anaesthesiology, using various methods of collecting behavioural data directly from the field while anaesthesiologists were doing their job. The methods used include direct observation, interviewing, and on-line verbal protocol recording with thinking aloud verbalisation. This paper describes findings from the field study and presents an analysis of how problem solving situations arise during the management of anaesthesia, a task similar to process control. Two classes of problem solving situations are identified: (1) managing the patient during non-critical but stressful and long lasting incidents—problem solving is characterised by competing goals and multiple hypotheses, and the memory load while keeping track of what is in the ‘pipeline’; (2) deploying preventive and preparatory strategies—the problem solving is characterised by feedforward control of system (patient) status in the face of anticipated inputs to the patient, preparation of preconditions of necessary and contingency procedures, and anticipation of troublesome situations to be avoided. A categorisation scheme is proposed to classify problem solving situations according to how they arise: incident-induced and strategy-induced.