The barberpole illusion is a visual illusion that reveals biases in the processing of visual motion in the human brain. This visual illusion occurs when a diagonally striped pole is rotated around its vertical axis (horizontally), it appears as though the stripes are moving in the direction of its vertical axis (downwards in the case of the animation to the right)[1] rather than around it.[2]
An example of the barberpole illusion. The grating is actually drifting downwards and to the right at 45 degrees, but its motion is captured by the elongated axis of the aperture.
In 1929, psychologistJ.P. Guilford informally noted a paradox in the perceived motion of stripes on a rotating barber pole. The barber pole turns in place on its vertical axis, but the stripes appear to move upwards rather than turning with the pole.[3] Guilford tentatively attributed the phenomenon to eye movements, but acknowledged the absence of data on the question.
In 1935, Hans Wallach published a comprehensive series of experiments related to this topic,[4] but since the article was in German it was not immediately known to English-speaking researchers. An English summary of the research was published in 1976[5] and a complete English translation of the 1935 paper was published in 1996.[6] Wallach's analysis focused on the interaction between the terminal points of the diagonal lines and the implicit aperture created by the edges of the pole.
Explanationedit
In this example the motion of the grating is identical to that in example 1, but the aperture is isotropic.
This illusion occurs because a bar or contour within a frame of reference provides ambiguous information about its "real" direction of movement. The actual motion of the line has many possibilities. The shape of the aperture thus tends to determine the perceived direction of motion for an otherwise identically moving contour. A vertically elongated aperture makes vertical motion dominant whereas a horizontally elongated aperture makes horizontal motion dominant. In the case of a circular or square aperture, the perceived direction of movement is usually orthogonal to the orientation of the stripes (diagonal, in this case). The perceived direction of movement relates to the termination of the line's end points within the inside border of the occluder. The vertical aperture, for instance, has longer edges at the vertical orientation, creating a larger number of terminators unambiguously moving vertically. This stronger motion signal forces us to perceive vertical motion. Functionally, this mechanism has evolved to ensure that we perceive a moving pattern as a rigid surface moving in one direction.[7]
Individual motion-sensitive neurons in the visual system have only limited information, as they see only a small portion of the visual field (a situation referred to as the "aperture problem"). In the absence of additional information the visual system prefers the slowest possible motion: i.e., motion orthogonal to the moving line.[8] The neurons which may correspond to perceiving barber-pole-like patterns have been identified in the visual cortex of ferrets.[9]
^Wallach, H. (1976). On perception. Quadrangle/New York Times Book Company. chap. IX.1
^Wuerger, S., Shapley, R., & Rubin, N. (1996). "'On the visually perceived direction of motion' by Hans Wallach: 60 years later." Perception-London, 25: 1317–1368.
^Todorović, Dejan (2002). (PDF). Psihologija. 35 (3–4). Serbia, Yugoslavia: Laboratory for Experimental Psychology, University of Belgrade: 209–223 UDC 159.937.075. doi:10.2298/psi0203209t. Archived from the original (PDF) on July 23, 2011. Retrieved November 26, 2010.
^Hoffman, Donald D. 2000. Visual Intelligence: How We Create What We See. W. W. Norton. ISBN0-393-31967-9
^Lees, Kevin (July 15, 2003). . Duke News. Durham, North Carolina: Duke University. Archived from the original on July 26, 2010. Retrieved December 14, 2010.
External linksedit
Wikimedia Commons has media related to Barberpole illusion.
Barpole effect animation and explanation.
January 01, 1970
barberpole, illusion, barberpole, illusion, visual, illusion, that, reveals, biases, processing, visual, motion, human, brain, this, visual, illusion, occurs, when, diagonally, striped, pole, rotated, around, vertical, axis, horizontally, appears, though, stri. The barberpole illusion is a visual illusion that reveals biases in the processing of visual motion in the human brain This visual illusion occurs when a diagonally striped pole is rotated around its vertical axis horizontally it appears as though the stripes are moving in the direction of its vertical axis downwards in the case of the animation to the right 1 rather than around it 2 An example of the barberpole illusion The grating is actually drifting downwards and to the right at 45 degrees but its motion is captured by the elongated axis of the aperture Contents 1 History 2 Explanation 3 Auditory analogue 4 See also 5 References 5 1 Notes 6 External linksHistory edit nbsp The barber s pole is commonly found outside barber shops In 1929 psychologist J P Guilford informally noted a paradox in the perceived motion of stripes on a rotating barber pole The barber pole turns in place on its vertical axis but the stripes appear to move upwards rather than turning with the pole 3 Guilford tentatively attributed the phenomenon to eye movements but acknowledged the absence of data on the question In 1935 Hans Wallach published a comprehensive series of experiments related to this topic 4 but since the article was in German it was not immediately known to English speaking researchers An English summary of the research was published in 1976 5 and a complete English translation of the 1935 paper was published in 1996 6 Wallach s analysis focused on the interaction between the terminal points of the diagonal lines and the implicit aperture created by the edges of the pole Explanation edit nbsp In this example the motion of the grating is identical to that in example 1 but the aperture is isotropic This illusion occurs because a bar or contour within a frame of reference provides ambiguous information about its real direction of movement The actual motion of the line has many possibilities The shape of the aperture thus tends to determine the perceived direction of motion for an otherwise identically moving contour A vertically elongated aperture makes vertical motion dominant whereas a horizontally elongated aperture makes horizontal motion dominant In the case of a circular or square aperture the perceived direction of movement is usually orthogonal to the orientation of the stripes diagonal in this case The perceived direction of movement relates to the termination of the line s end points within the inside border of the occluder The vertical aperture for instance has longer edges at the vertical orientation creating a larger number of terminators unambiguously moving vertically This stronger motion signal forces us to perceive vertical motion Functionally this mechanism has evolved to ensure that we perceive a moving pattern as a rigid surface moving in one direction 7 Individual motion sensitive neurons in the visual system have only limited information as they see only a small portion of the visual field a situation referred to as the aperture problem In the absence of additional information the visual system prefers the slowest possible motion i e motion orthogonal to the moving line 8 The neurons which may correspond to perceiving barber pole like patterns have been identified in the visual cortex of ferrets 9 Auditory analogue editSee also Strange loop A similar effect occurs in the Shepard s tone which is an auditory illusion 1 2 See also editScrew simple machine screws convert rotational motion to linear motion and exhibit the same mechanic Motion perception Auditory illusionReferences editNotes edit a b Barber Pole Illusion sandlotscience com Archived from the original on 28 November 2010 Retrieved November 14 2010 a b Massaro Dominic W ed Spring 2007 Book Reviews What Are Musical Paradox and Illusion PDF American Journal of Psychology 120 1 University of California Santa Cruz 123 170 124 132 Guilford J P 1929 Illusory Movement from a Rotating Barber Pole American Journal of Psychology 41 686 687 Wallach H 1935 Ueber visuell wahrgenommene Bewegungsrichtung Psychologische Forschung 20 325 380 doi 10 1007 bf02409790 S2CID 145400184 Wallach H 1976 On perception Quadrangle New York Times Book Company chap IX 1 Wuerger S Shapley R amp Rubin N 1996 On the visually perceived direction of motion by Hans Wallach 60 years later Perception London 25 1317 1368 Todorovic Dejan 2002 A new variant of the barberpole effect Psycholphysical data and computer simulations PDF Psihologija 35 3 4 Serbia Yugoslavia Laboratory for Experimental Psychology University of Belgrade 209 223 UDC 159 937 075 doi 10 2298 psi0203209t Archived from the original PDF on July 23 2011 Retrieved November 26 2010 Hoffman Donald D 2000 Visual Intelligence How We Create What We See W W Norton ISBN 0 393 31967 9 Lees Kevin July 15 2003 Rethinking How the Brain Sees Visual Features Duke neurobiologists study brain s visual processing region Duke News Durham North Carolina Duke University Archived from the original on July 26 2010 Retrieved December 14 2010 External links edit nbsp Wikimedia Commons has media related to Barberpole illusion Barpole effect animation and explanation Retrieved from https en wikipedia org w index php title Barberpole illusion amp oldid 1103097746, wikipedia, wiki, book, books, library,
