The Pulfrich effect is a psycho-optical phenomenon wherein lateral motion by an object in the field of view is interpreted by the brain as having a depth component, due to differences in processing speed between images from the two eyes. By putting a dark filter, as to cover one eye, the effect is achieved. The phenomenon is named for German physicist Carl Pulfrich who first described it in 1922.[Number One]



The subject in the classic Pulfrich effect experiment watches a pendulum as it swings in a plane perpendicular to the subjects line of vision . With a neutral density filter used (a darkened lens – typically grey) When the pendulum is put in front of the right eye it appears as an elliptical orbit swinging to the right and left, which changes the appearance from closer to farther.

The widely accepted explanation of the apparent depth is that a reduction in retinal illumination (relative to the fellow eye) renders a matching delay in signal transmission, sending forth immediate spatial disparity in moving articles. The probable reason this seems to occur is due to the visual latencies which are normally shorter for The visual system reacts faster to well lighted items compared to poorly lighted items This movement with idepth (first described by the German physicist Carl Pulfrich) The moving object is observed in the retinal illuminance and hence there is a difference in the signal latencies because of the distance between two eyes.

The Pulfrich effect, yielding about 15 meters, is scaled under real-life conditions with dark targets on a background of bright colors. When was The Delay for a factor of ten differences in average retinal luminance, and the percentage of it.[2]Three[4](Five) A delay can boost the monotonality with a decrease in lighting over a large (> six log-units) There is a vast spectrum of light.[2][3] The effect is also seen with bright targets on a black background and exhibits the same luminance-to-latency relationship.

This effect could happen at any time in several diseases of the eye such as cataracts.Six the optic neurtis[Seven][8] or the condition multiple sclerosis.NINE. In such cases, symptoms such as difficulties judging the paths of oncoming cars have been reported.

In visual media such as film and television, the Pulfrich effect is often used to produce 3-Dimensional imagery. As in other kinds of stereoscopy, glasses are used to create the illusion of a three-dimensional image. Implementing a neutral filter (example: the shaded black lens of a pair of sunglasses) above one eye, a picture, as it moves from the right to the left (or left to right, but NOT up and down) it seems like it's moving in depth, either closer to or further away from the one viewing it.

Because the Pulfrich effect depends on motion in a particular direction to instigate the illusion of depth, it is not useful as a general stereoscopic technique; for example it cannot be used to show a stationary object apparently extending into or out of the screen; similarly, objects moving vertically will not be seen as moving in depth. It can, however, be effective as a novelty effect in contrived visual scenarios. One benefit of material created to utilize the Pulfrich effect is it is totally harmonious with "regular" viewing eliminating the need of "special" glasses.

The effect became somewhat popular in TV during the 90s. For example, it was used in a "3D" motion television commercial in the 1990s, where objects moving in one direction appeared to be nearer to the viewer viewing the front of a tv screen and they seemed to be further away from the viewer when moved in the opposite direction. (located in the back of the television screen). To allow viewers to see the effect, the advertiser provided a large number of viewers with a pair of filters in a paper frame. One eye's filter was a rather dark neutral gray while the other was transparent. In this instance, the commericial was resticted to objects only (such as refrigerators and skateboarders) A directional dependency was determined by which eye was covered by the darker filter. This was done by moving down a steep hill from one side of the screen to the other.

In the Doctor Who of 1993, the Pulfrich effect was well utilized for the charity special Dimensions in Time. In Europe, there was a series of short 3D films shown on televison that were produced in the Netherlands. Glasses were sold at a chain of gas stations. Basically, these films were short travelogues of different Dutch locations. an adventure from the Power RangersThe First sold through McDonalds used "Circlescan 4D" technologyNumber two enclosed on brackets It is the Pulfrich effect on which it is based. The Bots Master and Space Strikers are two examples of programs that employ the Pulfrich effect; they achieve the effect using constantly moving layers. The videogame Orb-3D for the Nintendo Entertainment System used the effect through keeping the player's ship continually moving and included a pair of glasses. So did Jim Power: The Lost Dimension in 3-D for the popular Super Nintendo gameing system, utilizing interesting and unique scrolling backgrounds to an expecially great effect.

In United States and Canada, was discovered that six million 3D Pulfrich glasses were distributed to viewers for one of the hottest episode of Discovery Channel's Shark Week start on 2000.