The Mandelbaum effect is the tendency for the eye to focus nearby in conditions of poor visibility. It was first codified by J. Mandelbaum in 1960. [1] Because dirty glass can aggravate the effect, potentially causing a pilot or driver to miss seeing an obstacle or hazard, it is a strong safety argument for keeping windows clean. [2]
When visibility is poor, as at night during rainstorms or fog, the eye tends to relax and focus on its best distance, technically known as "empty field" or "dark focus". [3] This distance is usually just under one meter (one yard), but varies considerably among people. The tendency is aggravated by objects close to the eye, drawing focus closer. A common synonym for the Effect in FAA [4] and Transport Canada [5] usage is "empty-field myopia."
It has been shown that the Mandelbaum effect is not a refractive error in the usual sense: it is not a structural characteristic of the eyes, but the effect arises from normal variations of perception in the brain. [3] As in the aviation condition known as spatial disorientation, it is posited that some people are severely affected by the effect, some mildly, and some not at all. [6]
In aviation and automobile safety research, the Mandelbaum effect is a useful tool in determining bias in stressful conditions. There seem to be consistent patterns in pilots' and drivers' perceptions during poor visibility. Methods of compensating for the Mandelbaum effect are still subject to research. [7]
Motion sickness occurs due to a difference between actual and expected motion. Symptoms commonly include nausea, vomiting, cold sweat, headache, dizziness, tiredness, loss of appetite, and increased salivation. Complications may rarely include dehydration, electrolyte problems, or a lower esophageal tear.
A flight simulator is a device that artificially re-creates aircraft flight and the environment in which it flies, for pilot training, design, or other purposes. It includes replicating the equations that govern how aircraft fly, how they react to applications of flight controls, the effects of other aircraft systems, and how the aircraft reacts to external factors such as air density, turbulence, wind shear, cloud, precipitation, etc. Flight simulation is used for a variety of reasons, including flight training, the design and development of the aircraft itself, and research into aircraft characteristics and control handling qualities.
Myopia, also known as near-sightedness and short-sightedness, is an eye disease where light from distant objects focuses in front of, instead of on, the retina. As a result, distant objects appear blurry while close objects appear normal. Other symptoms may include headaches and eye strain. Severe myopia is associated with an increased risk of macular degeneration, retinal detachment, cataracts, and glaucoma.
The visual system is the physiological basis of visual perception. The system detects, transduces and interprets information concerning light within the visible range to construct an image and build a mental model of the surrounding environment. The visual system is associated with the eye and functionally divided into the optical system and the neural system.
A head-up display, or heads-up display, also known as a HUD or head-up guidance system (HGS), is any transparent display that presents data without requiring users to look away from their usual viewpoints. The origin of the name stems from a pilot being able to view information with the head positioned "up" and looking forward, instead of angled down looking at lower instruments. A HUD also has the advantage that the pilot's eyes do not need to refocus to view the outside after looking at the optically nearer instruments.
Refractive error is a problem with focusing light accurately on the retina due to the shape of the eye and/or cornea. The most common types of refractive error are near-sightedness, far-sightedness, astigmatism, and presbyopia. Near-sightedness results in far away objects being blurry, far-sightedness and presbyopia result in close objects being blurry, and astigmatism causes objects to appear stretched out or blurry. Other symptoms may include double vision, headaches, and eye strain.
A head-mounted display (HMD) is a display device, worn on the head or as part of a helmet, that has a small display optic in front of one or each eye. HMDs have many uses including gaming, aviation, engineering, and medicine.
Eye tracking is the process of measuring either the point of gaze or the motion of an eye relative to the head. An eye tracker is a device for measuring eye positions and eye movement. Eye trackers are used in research on the visual system, in psychology, in psycholinguistics, marketing, as an input device for human-computer interaction, and in product design. In addition, eye trackers are increasingly being used for assistive and rehabilitative applications such as controlling wheelchairs, robotic arms, and prostheses. Recently, eye tracking has been examined as a tool for the early detection of autism spectrum disorder. There are several methods for measuring eye movement, with the most popular variant using video images to extract eye position. Other methods use search coils or are based on the electrooculogram.
Mandelbaum is a Jewish (Ashkenazic) surname from the German Mandelbaum ‘almond tree’. Notable people with the surname include:
Chino Airport is a county-owned airport about three miles southeast of Chino, in San Bernardino County, California, United States. The Federal Aviation Administration's National Plan of Integrated Airport Systems for 2007–2011 classified it as a reliever airport, due to its proximity to the Ontario International Airport and the John Wayne Airport.
Underwater vision is the ability to see objects underwater, and this is significantly affected by several factors. Underwater, objects are less visible because of lower levels of natural illumination caused by rapid attenuation of light with distance passed through the water. They are also blurred by scattering of light between the object and the viewer, also resulting in lower contrast. These effects vary with wavelength of the light, and color and turbidity of the water. The vertebrate eye is usually either optimised for underwater vision or air vision, as is the case in the human eye. The visual acuity of the air-optimised eye is severely adversely affected by the difference in refractive index between air and water when immersed in direct contact. Provision of an airspace between the cornea and the water can compensate, but has the side effect of scale and distance distortion. The diver learns to compensate for these distortions. Artificial illumination is effective to improve illumination at short range.
Under certain conditions, laser light or other bright lights directed at aircraft can be a hazard. The most likely scenario is when a bright visible laser light causes distraction or temporary flash blindness to a pilot, during a critical phase of flight such as landing or takeoff. It is far less likely, though still possible, that a visible or invisible beam could cause permanent harm to a pilot's eyes. Although laser weapons are under development by armed forces, these are so specialized, expensive and controlled that it is improbable for non-military lasers to cause structural damage to an aircraft.
Fatigue is a major safety concern in many fields, but especially in transportation, because fatigue can result in disastrous accidents. Fatigue is considered an internal precondition for unsafe acts because it negatively affects the human operator's internal state. Research has generally focused on pilots, truck drivers, and shift workers.
Scholar, educator, and philanthropist Herschel Leibowitz is widely recognized for his research in visual perception and for his symbiotic approach to conducting research that both advanced theory and helped in the understanding and relief of societal problems. His research on transportation safety included studies of nearsightedness during night driving, vision during civil twilight, an illusion that underlies the behavior of motorists involved in auto-train collisions, susceptibility of pilots to illusions caused by visual-vestibular interactions, and the design of aircraft instrument panels.
The chameleon is among the most highly visually-oriented lizards, using this sense in prey capture, mating behavior, and predator avoidance. Unique features of chameleon vision include a negative lens, a positive cornea, and monocular focusing. The development of the chameleon visual system could have evolved to aid in prey capture and/or in predator avoidance.
The health effects of 3D are the aspects in which the human body is altered after the exposure of three-dimensional (3D) graphics. These health effects typically only occur when viewing stereoscopic, autostereoscopic, and multiscopic displays. Newer types of 3D displays like light field or holographic displays do not cause the same health effects. The viewing of 3D stereoscopic stimuli can cause symptoms related to vision disorders that the individual already had, as a person with a healthy binocular vision shouldn't experience any side effects under three-dimensional exposure.
Instrument myopia is the tendency of a person with normal eyes to focus them too close when looking into an optical instrument at its image. Optical instruments include viewfinders, telescopes, binoculars, and microscopes. For example, through a microscope, a person might focus the eyes to one meter distance although it can present an image at six meters distance.
Virtual reality sickness occurs when exposure to a virtual environment causes symptoms that are similar to motion sickness symptoms. The most common symptoms are general discomfort, eye strain, headache, stomach awareness, nausea, vomiting, pallor, sweating, fatigue, drowsiness, disorientation, and apathy. Other symptoms include postural instability and retching. Common causes are low frame rate, input lag, and the vergence-accommodation-conflict.
An enhanced flight vision system is an airborne system which provides an image of the scene and displays it to the pilot, in order to provide an image in which the scene and objects in it can be better detected. In other words, an EFVS is a system which provides the pilot with an image which is better than unaided human vision. An EFVS includes imaging sensors such as a color camera, infrared camera or radar, and typically a display for the pilot, which can be a head-mounted display or head-up display. An EFVS may be combined with a synthetic vision system to create a combined vision system.
Vergence-accommodation conflict (VAC), also known as accommodation-vergence conflict, is a visual phenomenon that occurs when the brain receives mismatching cues between vergence and accommodation of the eye. This commonly occurs in virtual reality devices, augmented reality devices, 3D movies, and other types of stereoscopic displays and autostereoscopic displays. The effect can be unpleasant and cause eye strain.