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. Because dirty glass can aggravate the effect, potentially causing a

pilot An aircraft pilot or aviator is a person who controls the flight of an aircraft by operating its Aircraft flight control system, directional flight controls. Some other aircrew, aircrew members, such as navigators or flight engineers, are al ...

or driver to miss seeing an obstacle or hazard, it is a strong safety argument for keeping windows clean.

Discussion

When visibility is poor, as at night during rainstorms or fog, the

eye An eye is a sensory organ that allows an organism to perceive visual information. It detects light and converts it into electro-chemical impulses in neurons (neurones). It is part of an organism's visual system. In higher organisms, the ey ...

tends to relax and focus on its best distance, technically known as "empty field" or "dark focus". 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 and

Transport Canada Transport Canada () is the Ministry (government department), department within the Government of Canada responsible for developing regulations, Policy, policies and Public services, services of road, rail, marine and air Transport in Canada, tra ...

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. As in the aviation condition known as

spatial disorientation Spatial disorientation is the inability to determine position or relative motion, commonly occurring during periods of challenging visibility, since visual system, vision is the dominant sense for orientation. The auditory system, vestibular system ...

, it is posited that some people are severely affected by the effect, some mildly, and some not at all. In

aviation Aviation includes the activities surrounding mechanical flight and the aircraft industry. ''Aircraft'' include fixed-wing and rotary-wing types, morphable wings, wing-less lifting bodies, as well as lighter-than-air aircraft such as h ...

and

automobile safety Automotive safety is the study and practice of automotive design, construction, equipment and regulation to minimize the occurrence and consequences of traffic collisions involving motor vehicles. Road traffic safety more broadly includes roadw ...

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.

References

{{Reflist Vision

Discussion

See also

References