Coordination of gaze and action during high-speed steering and obstacle avoidance.

When humans navigate through complex environments, they coordinate gaze and steering to sample the visual information needed to guide movement. Gaze and steering behavior have been extensively studied in the context of automobile driving along a winding road, leading to accounts of movement along well-defined paths over flat, obstacle-free surfaces. However, humans are also capable of visually guiding self-motion in environments that are cluttered with obstacles and lack an explicit path. An extreme example of such behavior occurs during first-person view drone racing, in which pilots maneuver at high speeds through a dense forest. In this study, we explored the gaze and steering behavior of skilled drone pilots. Subjects guided a simulated quadcopter along a racecourse embedded within a custom-designed forest-like virtual environment. The environment was viewed through a head-mounted display equipped with an eye tracker to record gaze behavior. In two experiments, subjects performed the task in multiple conditions that varied in terms of the presence of obstacles (trees), waypoints (hoops to fly through), and a path to follow. Subjects often looked in the general direction of things that they wanted to steer toward, but gaze fell on nearby objects and surfaces more often than on the actual path or hoops. Nevertheless, subjects were able to perform the task successfully, steering at high speeds while remaining on the path, passing through hoops, and avoiding collisions. In conditions that contained hoops, subjects adapted how they approached the most immediate hoop in anticipation of the position of the subsequent hoop. Taken together, these findings challenge existing models of steering that assume that steering is tightly coupled to where actors look. We consider the study's broader implications as well as limitations, including the focus on a small sample of highly skilled subjects and inherent noise in measurement of gaze direction.

A neural active inference model of perceptual-motor learning.

The active inference framework (AIF) is a promising new computational framework grounded in contemporary neuroscience that can produce human-like behavior through reward-based learning. In this study, we test the ability for the AIF to capture the role of anticipation in the visual guidance of action in humans through the systematic investigation of a visual-motor task that has been well-explored-that of intercepting a target moving over a ground plane. Previous research demonstrated that humans performing this task resorted to anticipatory changes in speed intended to compensate for semi-predictable changes in target speed later in the approach. To capture this behavior, our proposed "neural" AIF agent uses artificial neural networks to select actions on the basis of a very short term prediction of the information about the task environment that these actions would reveal along with a long-term estimate of the resulting cumulative expected free energy. Systematic variation revealed that anticipatory behavior emerged only when required by limitations on the agent's movement capabilities, and only when the agent was able to estimate accumulated free energy over sufficiently long durations into the future. In addition, we present a novel formulation of the prior mapping function that maps a multi-dimensional world-state to a uni-dimensional distribution of free-energy/reward. Together, these results demonstrate the use of AIF as a plausible model of anticipatory visually guided behavior in humans.

Temporal RIT-Eyes: From Real Infrared Eye-Images to Synthetic Sequences of Gaze Behavior.

Current methods for segmenting eye imagery into skin, sclera, pupil, and iris cannot leverage information about eye motion. This is because the datasets on which models are trained are limited to temporally non-contiguous frames. We present Temporal RIT-Eyes, a Blender pipeline that draws data from real eye videos for the rendering of synthetic imagery depicting natural gaze dynamics. These sequences are accompanied by ground-truth segmentation maps that may be used for training image-segmentation networks. Temporal RIT-Eyes relies on a novel method for the extraction of 3D eyelid pose (top and bottom apex of eyelids/eyeball boundary) from raw eye images for the rendering of gaze-dependent eyelid pose and blink behavior. The pipeline is parameterized to vary in appearance, eye/head/camera/illuminant geometry, and environment settings (indoor/outdoor). We present two open-source datasets of synthetic eye imagery: sGiW is a set of synthetic-image sequences whose dynamics are modeled on those of the Gaze in Wild dataset, and sOpenEDS2 is a series of temporally non-contiguous eye images that approximate the OpenEDS-2019 dataset. We also analyze and demonstrate the quality of the rendered dataset qualitatively and show significant overlap between latent-space representations of the source and the rendered datasets.

EllSeg: An Ellipse Segmentation Framework for Robust Gaze Tracking.

Ellipse fitting, an essential component in pupil or iris tracking based video oculography, is performed on previously segmented eye parts generated using various computer vision techniques. Several factors, such as occlusions due to eyelid shape, camera position or eyelashes, frequently break ellipse fitting algorithms that rely on well-defined pupil or iris edge segments. In this work, we propose training a convolutional neural network to directly segment entire elliptical structures and demonstrate that such a framework is robust to occlusions and offers superior pupil and iris tracking performance (at least 10% and 24% increase in pupil and iris center detection rate respectively within a two-pixel error margin) compared to using standard eye parts segmentation for multiple publicly available synthetic segmentation datasets.

Gaze-in-wild: A dataset for studying eye and head coordination in everyday activities.

The study of gaze behavior has primarily been constrained to controlled environments in which the head is fixed. Consequently, little effort has been invested in the development of algorithms for the categorization of gaze events (e.g. fixations, pursuits, saccade, gaze shifts) while the head is free, and thus contributes to the velocity signals upon which classification algorithms typically operate. Our approach was to collect a novel, naturalistic, and multimodal dataset of eye + head movements when subjects performed everyday tasks while wearing a mobile eye tracker equipped with an inertial measurement unit and a 3D stereo camera. This Gaze-in-the-Wild dataset (GW) includes eye + head rotational velocities (deg/s), infrared eye images and scene imagery (RGB + D). A portion was labelled by coders into gaze motion events with a mutual agreement of 0.74 sample based Cohen's κ. This labelled data was used to train and evaluate two machine learning algorithms, Random Forest and a Recurrent Neural Network model, for gaze event classification. Assessment involved the application of established and novel event based performance metrics. Classifiers achieve ~87% human performance in detecting fixations and saccades but fall short (50%) on detecting pursuit movements. Moreover, pursuit classification is far worse in the absence of head movement information. A subsequent analysis of feature significance in our best performing model revealed that classification can be done using only the magnitudes of eye and head movements, potentially removing the need for calibration between the head and eye tracking systems. The GW dataset, trained classifiers and evaluation metrics will be made publicly available with the intention of facilitating growth in the emerging area of head-free gaze event classification.

Comparison of the time required for manual (visually read) and semi-automated POCT urinalysis and pregnancy testing with associated electronic medical record (EMR) transcription errors.

BACKGROUND: POCT urinalysis (UA) and urine pregnancy tests (UPT) are routinely performed in obstetrics and gynecology (Ob/Gyn) clinics by dipstick and pregnancy test kit methods respectively. In this study, we compared the time, efficiency and accuracy of these tests using manual, visually read methods and a semi-automated analyzer that was not interfaced to the EMR. METHODS: We prospectively enrolled 2525 patients at five Ob/Gyn clinics. Urine samples were tested using three different dipsticks for UA (2, 7 and 10 test pads) and the Sure-Vue™ urine pregnancy test kit. The samples were analyzed on the CLINITEK Status® Connect System and results compared for time taken and errors in results' transcription. RESULTS: Using the CLINITEK Status Connect System, average test time and average total test time for UA dipsticks 7 and 10 test pads was significantly less than the manual, visually read method (0.77 and 0.64 min, respectively; p < 0.001). The average test time for manual, visually read Chem 2 was significantly less than the CLINITEK Status Connect System (0.09 min; p = 0.005), but not the average total test time (0.08 min; p = 0.33). Average test time for a negative UPT using the CLINITEK Status Connect System was significantly greater (0.87 min; p < 0.001). We found a transcription error rate of 0.3-1.7% for UA results and none for UPT. About 8% of UA and 12% of UPT results were not documented in EMR. CONCLUSION: The CLINITEK Status Connect System was more efficient than the manual, visually read process and if interfaced with the EMR would eliminate errors and non-documentation of results.

From lab-based studies to eye-tracking in virtual and real worlds: conceptual and methodological problems and solutions. Symposium 4 at the 20th European Conference on Eye Movement Research (ECEM) in Alicante, 20.8.2019.

Wearable mobile eye trackers have great potential as they allow the measurement of eye movements during daily activities such as driving, navigating the world and doing groceries. Although mobile eye trackers have been around for some time, developing and operating these eye trackers was generally a highly technical affair. As such, mobile eye-tracking research was not feasible for most labs. Nowadays, many mobile eye trackers are available from eye-tracking manufacturers (e.g. Tobii, Pupil labs, SMI, Ergoneers) and various implementations in virtual/augmented reality have recently been released.The wide availability has caused the number of publications using a mobile eye tracker to increase quickly. Mobile eye tracking is now applied in vision science, educational science, developmental psychology, marketing research (using virtual and real supermarkets), clinical psychology, usability, architecture, medicine, and more. Yet, transitioning from lab-based studies where eye trackers are fixed to the world to studies where eye trackers are fixed to the head presents researchers with a number of problems. These problems range from the conceptual frameworks used in world-fixed and head-fixed eye tracking and how they relate to each other, to the lack of data quality comparisons and field tests of the different mobile eye trackers and how the gaze signal can be classified or mapped to the visual stimulus. Such problems need to be addressed in order to understand how world-fixed and head-fixed eye-tracking research can be compared and to understand the full potential and limits of what mobile eye-tracking can deliver. In this symposium, we bring together presenting researchers from five different institutions (Lund University, Utrecht University, Clemson University, Birkbeck University of London and Rochester Institute of Technology) addressing problems and innovative solutions across the entire breadth of mobile eye-tracking research. Hooge, presenting Hessels et al. paper, focus on the definitions of fixations and saccades held by researchers in the eyemovement field and argue how they need to be clarified in order to allow comparisons between world-fixed and head-fixed eye-tracking research. - Diaz et al. introduce machine-learning techniques for classifying the gaze signal in mobile eye-tracking contexts where head and body are unrestrained. Niehorster et al. compare data quality of mobile eye trackers during natural behavior and discuss the application range of these eye trackers. Duchowski et al. introduce a method for automatically mapping gaze to faces using computer vision techniques. Pelz et al. employ state-of-the-art techniques to map fixations to objects of interest in the scene video and align grasp and eye-movement data in the same reference frame to investigate the guidance of eye movements during manual interaction. Video stream: https://vimeo.com/357473408.

Assessment of an augmented reality apparatus for the study of visually guided walking and obstacle crossing.

To walk through the cluttered natural environment requires visually guided and anticipatory adjustments to gait in advance of upcoming obstacles. However, scientific investigation of visual contributions to obstacle crossing have historically been limited by the practical issues involved with the repeated presentation of multiple obstacles upon a ground plane. This study evaluates an approach in which the perception of a 3D obstacle is generated from 2D projection onto the ground plane with perspective correction based on the subject's motion-tracked head position. The perception of depth is further reinforced with the use of stereoscopic goggles. To evaluate the validity of this approach, behavior was compared between approaches to two types of obstacles in a blocked design: physical obstacles, and the augmented reality (AR) obstacles projected upon the ground plane. In addition, obstacle height, defined in units of leg length (LL), was varied on each trial (0.15, 0.25, 0.35 LL). Approaches to ended with collision on 0.8% of trials with physical obstacles per subject, and on 1.4% trials with AR obstacles. Collisions were signaled by auditory feedback. Linear changes in the height of both AR and physical obstacles produced linear changes in maximum step height, preserving a constant clearance magnitude across changes in obstacle height. However, for AR obstacles, approach speed was slower, the crossing step peaked higher above the obstacle, and there was greater clearance between the lead toe and the obstacle. These results suggest that subjects were more cautious when approaching and stepping over AR obstacles.

The pickup of visual information about size and location during approach to an obstacle.

The present study investigated differences in the pickup of information about the size and location of an obstacle in the path of locomotion. The main hypothesis was that information about obstacle location is most useful when it is sampled at a specific time during the approach phase, whereas information about obstacle size can be sampled at any point during the last few steps. Subjects approached and stepped over obstacles in a virtual environment viewed through a head-mounted display. In Experiment 1, a horizontal line on the ground indicating obstacle location was visible throughout the trial while information about obstacle height and depth was available only while the subject was passing through a viewing window located at one of four locations along the subject's path. Subjects exhibited more cautious behavior when the obstacle did not become visible until they were within one step length, but walking behavior was at most weakly affected in the other viewing window conditions. In Experiment 2, the horizontal line indicating obstacle location was removed, such that no information about the obstacle (size or location) was available outside of the viewing window. Subjects adopted a more cautious strategy compared to Experiment 1 and differences between the viewing window conditions and the full vision control condition were observed across several measures. The differences in walking behavior and performance across the two experiments support the hypothesis that walkers have greater flexibility in when they can sample information about obstacle size compared to location. Such flexibility may impact gaze and locomotor control strategies, especially in more complex environments with multiple objects and obstacles.

A 7-week-old Nepali girl with a perianal ulcer: brief report.

Cytomegalovirus (CMV) can rarely present with skin findings. Cutaneous CMV is most often found in patients who are immunocompromised because of acquired immunodeficiency syndrome, lymphoma, or other conditions. We present a rare case of an immunocompetent 7-week-old girl with a perianal ulcer attributed to CMV.

Anticipation from biological motion: the goalkeeper problem.

People can often anticipate the outcome of another person's actions based on visual information available in the movements of the other person's body. We investigated this problem by studying how goalkeepers anticipate the direction of a penalty kick in soccer. The specific aim was to determine whether the information used to anticipate kick direction is best characterized as local to a particular body segment or distributed across multiple segments. In Experiment 1, we recorded the movements of soccer players as they kicked balls into a net. Using a novel method for analyzing motion capture data, we identified sources of local and distributed information that were reliable indicators of kick direction. In Experiments 2 and 3, subjects were presented with animations of kickers' movements prior to foot-to-ball contact and instructed to judge kick direction. Judgments were consistent with the use of distributed information, with a possible small contribution of local information.

Atrial fibrillation from thyroid storm.

BACKGROUND: Thyroid storm is an often-discussed but rare presentation to emergency departments (EDs). The clinical presentation of a thyroid storm is the result of a hyperthyroid state that may result in significant morbidity or disability, or even death. Typically, patients are aware of their hyperthyroid condition, and may be able to recognize an episode of thyroid storm. However, the first presentation of hyperthyroidism could, in fact, be from thyrotoxic crisis. OBJECTIVES: To review the presentation of thyroid storm, including tachycardia, hyperpyrexia, agitation, and altered mental status, which can be easily misdiagnosed as drug intoxication. CASE REPORT: We present the case of an otherwise healthy young adult who was sent to the ED by an outpatient care provider for generalized and vague symptoms of "feeling unwell" that was eventually diagnosed in the ED as thyrotoxic crisis. CONCLUSION: We use this case to emphasize that thyrotoxic crisis should be at least considered in the differential diagnosis of a patient with this presentation, and to highlight how, even with apparently usual and effective treatments, a patient may still decompensate.

Altered mental status from acyclovir.

BACKGROUND: Acyclovir is widely used in the treatment of herpes virus infections, particularly herpes simplex virus and varicella-zoster virus. Acyclovir, when given promptly upon the start of a herpes zoster eruption, speeds healing and diminishes acute pain. OBJECTIVES: Because acyclovir is a commonly used medication, it is crucial for health providers to be aware of appropriate dosing as well as possible side effects. We present this case to increase awareness of the potential for inappropriate dosing of acyclovir and the presentations of patients with toxic effects. CASE REPORT: We report the case of a 65-year-old man with a past medical history significant for chronic kidney disease who presented to the Emergency Department with progressive confusion and ataxia over 2 days. Thorough questioning in the patient's native language revealed that he had recently started a medication for a "rash." Neither he nor his family knew the name of the new medication; further investigation revealed it to be acyclovir. Although other diagnoses were considered in the differential diagnosis for this patient with altered mental status, he was treated for presumed acyclovir toxicity and given prompt dialysis, upon which his symptoms resolved. CONCLUSION: It is important for physicians to remember that even common medications such as acyclovir can have serious side effects and complications. In this case, renal dosing was not used in a patient on hemodialysis. Acyclovir must be renally dosed and carefully monitored through drug level measurement in patients with limited kidney function to prevent serious side effects, such as the neurological sequelae demonstrated in this case report. Emergency physicians should be aware of the potential for inappropriate dosing of this medication and the presentations of patients with toxic effects.

A toddler with facial nodules: a case of idiopathic facial aseptic granuloma.

We describe the case of a 3-year-old boy who presented with several asymptomatic facial nodules present for six months. A skin biopsy obtained from the nodules showed a moderately well-defined granuloma in the superficial and deep dermis. A squamous epithelial lined cyst, extravasated keratin, or shadow cells were not identified. Bartonella henselae titers and the Coccidioidomycosis immitis immunodiffusion test were negative; a Tuberculin Skin Test was non-reactive. Fite, Periodic acid-Schiff (PAS) and Gomori-Grocott methenamine silver (GMS) stains failed to identify microorganisms. In addition, tissue cultures for bacteria, fungus, and acid fast bacilli were negative. In light of the clinical findings, histology, and negative cultures, a diagnosis of idiopathic facial aseptic granuloma (IFAG) was made. After the biopsy, the child was treated with erythromycin and clarithromycin, each for one month, and the lesions slowly improved.

Postoperative pain following foot and ankle surgery: a prospective study.

BACKGROUND: Orthopaedic procedures have been reported to have the highest incidence of pain compared to other types of operations. There are limited studies in the literature that investigate postoperative pain. MATERIALS AND METHODS: A prospective study of 98 patients undergoing orthopedic foot and ankle operations was undertaken to evaluate their pain experience. A Short-Form McGill Pain Questionnaire (SF-MPQ) was administered preoperatively and postoperatively. RESULTS: The results showed that patients who experienced pain before the operation anticipated feeling higher pain intensity immediately postoperatively. Patients, on average, experienced higher pain intensity 3 days after the operation than anticipated. The postoperative pain intensity at 3 days was the most severe, while postoperative pain intensity at 6 weeks was the least severe. Age, gender and preoperative diagnosis (acute versus chronic) did not have a significant effect on the severity of pain that patients experienced. Six weeks following the operation, the majority of patients felt no pain. In addition, the severity of preoperative pain was highly predictive of their anticipated postoperative pain and 6-week postoperative pain, and both preoperative pain and anticipated pain predict higher immediate postoperative pain. CONCLUSION: The intensity of patients' preoperative pain was predictive of the anticipated postoperative pain. Patients' preoperative pain and anticipated postoperative pain were independently predictive of the 3-day postoperative pain. The higher pain intensity a patient experienced preoperatively suggested that their postoperative pain severity would be greater. Therefore, surgeons should be aware of these findings when treating postoperative pain after orthopaedic foot and ankle operations.

Pott's Puffy tumor after minor head trauma.

Posttraumatic osteomyelitis may occur as a direct result of bony injury after trauma or arise as a nosocomial infection after the treatment of trauma. Most cases arise after an open fracture, but bony infection can also arise from spread of infection from contiguous soft tissues or by puncture wounds. Motor vehicle accidents, sport injuries, and the use of orthopedic hardware to manage trauma have contributed to the apparent increase in prevalence of posttraumatic osteomyelitis. We report on a case of Pott's Puffy tumor in a previously healthy woman who had an episode of minor forehead trauma 1 month before presentation to the emergency department (ED), complaining of persistent headache and swelling of her forehead. Results of computed tomography (CT) revealed features characteristic of this condition. After postobliteration of the left frontal sinus via a bicoronal approach with an iliac crest bone graft and some dental extractions and 2 weeks of antibiotic therapy, the patient achieved a complete recovery.