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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.

Objective The present study tests the hypothesis that humans are capable of predicting the state of a system during visual occlusion, an assumption often made in models of sampling behaviour, but seldom tested. Background In 1967, John Senders introduced the visual occlusion paradigm to evaluate attentional demand of tasks such as automobile driving. Despite multiple studies employing this paradigm, the concept of operators actually being able to resolve uncertainty during occlusion by predicting system output has remained unvalidated. Method A self-paced visual occlusion monitoring task was contrived, involving a randomly rotating basin with a ball at the bottom. Participants were required to detect critical events (ball falling off the edge) while looking only as often as subjectively deemed necessary. Assuming the need to resolve uncertainty imposed by the random rotations, we examined relations between occlusion durations and system states preceding occlusion, for different glance durations, to infer whether predicting may have taken place. Results Results suggested that glance requests were consistent with the use of simple first order predictions. This pertained not only for longer (300 and 500 ms) glances, but even for 100 ms glances whenever critical events were imminent. Conclusion The presumption that human operators are capable, under certain circumstances, of predicting system state in the absence of visual information appears feasible; however, glance duration plays an important role. Applications By providing support for some of its basic premises, the use of Senders’ visual occlusion paradigm as a potential tool for evaluating human monitoring performance has been strengthened.

This article addresses some of the challenges involved with creating a stereoscopic video augmented reality “X-ray vision” display for near-field applications, which enables presentation of computer-generated objects as if they lie behind a real object surface, while maintaining the ability to effectively perceive information that might be present on that surface. To achieve this, we propose a method in which patterns consisting of randomly distributed dots are overlaid onto the real surface prior to the rendering of a virtual object behind the real surface using stereoscopic disparity. It was hypothesized that, even though the virtual object is occluding the real object’s surface, the addition of the random dot patterns should increase the strength of the binocular disparity cue, resulting in improved performance in localizing the virtual object behind the surface. In Phase I of the experiment reported here, the feasibility of the display principle was confirmed, and concurrently the effects of relative dot size and dot density on the presence and sensitivity of any perceptual bias in localizing the virtual object within the vicinity of a flat, real surface with a periodic texture were assessed. In Phase II, the effect of relative dot size and dot density on perceiving the impression of transparency of the same real surface while preserving detection of surface information was investigated. Results revealed an advantage of the proposed method in comparison with the “No Pattern” condition for the transparency ratings. Surface information preservation was also shown to decrease with increasing dot density and relative dot size.

BackgroundMany interventions have been implemented to improve hand hygiene compliance, each with varying effects and monetary costs. Although some previous studies have addressed the issue of conspicuousness, we found only 1 study that considered improving hand hygiene by using flashing lights.MethodOur attention theory–based hypothesis tested whether a simple red light flashing at 2-3 Hz affixed to the alcohol gel dispensers, within the main hospital entrance, would increase hand hygiene compliance over the baseline rate. Baseline and intervention observations were completed over five 60-minute periods (Monday-Friday) from 7:30 to 8:30 AM using a covert observation method.ResultsBaseline hand hygiene compliance was 12.4%. Our intervention increased compliance to 23.5% during cold weather and 27.1% during warm weather. Overall, our pooled compliance rate increased to 25.3% (P < .0001).ConclusionsA simple, inexpensive flashing red light affixed to alcohol gel dispensers was sufficiently salient to approximately double overall hand hygiene compliance within the main hospital entrance. We hypothesize that our intervention drew attention to the dispensers, which then reminded employees and visitors alike to wash their hands. Compliance was worse during cold days, presumably related to more individuals wearing gloves.

A two phase project is described for redesigning and evaluating paramedic response bags, one of the key pieces of equipment used by emergency medical services. Adopting a user-centred approach, Phase I involved first educating active service paramedics about ergonomic principles, and then collaborating with them to conceptualise a new type of response bag, based on separate colour coded kits, each containing related equipment items. Phase II describes a formal evaluation study, involving simulated procedures with a patient mannequin and active service paramedics in a real ambulance. Results indicated subjective preferences for the new bags, where 62% of the paramedics believed it was easier to find equipment in the new bag and 65% preferred the new bags overall. No detrimental effects were attributed to the transition to the new bag. Also discussed are the advantages of the participatory design approach, as well as design guidelines and implications for paramedic operations.

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.

Accurate measurement of growth in infants and children is important, as it reflects a child's nutritional status and overall health. Conventional methods of measuring length and height are challeng...

Field studies have frequently been advocated as a means for understanding cognitive activities in naturalistic settings. However, there are several fundamental obstacles that one has to overcome to conduct a field study. This paper discusses two of these obstacles in the context of studying problem solving in complex environments: defining goals of a field study and justifying methods used in data analysis. Based on our experience from a recently finished field study, we outline a framework for understanding the nature of field studies and suggest a specific approach to data analysis. We argue that the goal of field studies should not be limited to hypothesis testing, and that the process of data analysis in field studies can be viewed as an inductive abstraction process. Our field study is used to illustrate the abstraction approach to data analysis and how the obstacles in field studies were dealt with. Through these discussions, we encourage researchers to engage in more field studies.

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.