Pulfrich Phenomenon and perceived number of reversals of rotation directions with stereoscopic rotary grid cube A Unkelbach |
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Vision Sciences and Business, Hochschule Aalen, Germany
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| Observing ambiguous stereoscopic shadow-images of an rotating Necker cube the perception changed between two different directions of rotation (reversals), while the cube itself didn't change it's direction of rotation. The stereoscopic half images originated from shadow projections, while the wire framed cube was illuminated simultaneously by a "red" and a "green" LED. Looking with one eye through a red and with the other eye through a green filter and after fusion of the two stereoscopic half images most observers perceived a rotating three dimensional cube. Sudden brightness reduction of one specific stereoscopic half image or simultaneous presentation of a brighter and a darker stereoscopic half image during the whole time of presentation caused an increase of reversals. Explanation: the fusion of the different bright retinal pictures of the rotating cube originates a Pulfrich Phenomenon causing a change form perception of the rotary cube. As a function of the direction of rotation and depending on which eye the brighter retinal picture is present, either a more flattened cube is perceived or a distorted cube with a tremendous increase in the depth. In the first case the number of reversals increased because of the reduced depth information of the flattened cube. |
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