Sham motion

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Strobiscopic movement in the phenakistiscope

The term apparent motion (Engl. Apparent motion or apparent movement ) is more broadly for the perception of motion for objects that are in phisikalischen not really make sense. So it is a motion illusion . In a narrower sense, this means stroboscopic movement - also known as beta movement. This is the perception of movement when viewing a sequence of slightly varied individual images.

In addition to these everyday apparent movements, there is also a disturbance of visual perception known as oscillopsia , in which the environment appears blurred to the observer, especially when fixing objects or while he is moving.

Perception of apparent movement based on discrete stimuli

Forms of pseudo movements are of particular importance, in which actually discrete movement stimuli are perceived as continuous movement, because this is, among other things, the basis of realistic movement perception in film .

Siegfried Exner described in 1875 that the successive lighting up of two closely spaced sparks can give the impression of movement . At the beginning of the 20th century, Max Wertheimer analyzed in detail the perception of movement based on two stimuli presented one after the other and he documented the conditions under which an “optimal movement” can be perceived. He also described a shadow-like, objectless movement that was perceived by his test subjects under certain conditions. The latter is now usually referred to as the Phi phenomenon . Wertheimer actually referred the term “phi movement” to all of the pseudo movements he investigated, including the “optimal movement” which, under certain conditions, cannot be distinguished from a real movement, as he demonstrated.

Friedrich Kenkel later introduced the term beta movement for “optimal movement” . He differentiated this from a variant in which an optical illusion such as the Müller-Lyer illusion is also involved, which he called the alpha movement. For other very special test arrangements, the Greek letters gamma (γ), delta (δ) and epsilon (ε) were introduced later. Only the term “beta movement” has gained greater importance and has survived to this day. which is often used synonymously with the term " stroboscopic movement ".

At the end of the 20th century, Wertheimer's thesis was confirmed for stroboscopic movement that under certain conditions it is perception that is analogous to real movement. This is true when the viewing angle distance between two successive discrete stimuli is relatively small. This has been called a short-range apparent movement to distinguish it from a long-range apparent movement , which apparently involves higher cognitive processes.

Other forms of apparent movement

Deceptions that are based on an exchange of moving and stationary objects are also referred to as pseudo movements. This includes, for example, the landscape that appears to fly by when looking out of the window of a moving train. The opposite effect, known as vection , can also occur: For example, if the train on the neighboring track starts moving in a train station, the impression can arise that your own train is traveling in the opposite direction.

The so-called jump of the thumb can also be described as a sham movement. If you hold your thumb close to your face and alternately close your left and right eyes, your thumb seems to jump back and forth. This effect is created by changing the angle of view, whereby the targeted object seems to move in front of the more distant background, analogous to parallax .

The perception of apparent movements is also possible due to so-called secondary movement effects. Similar to the afterimages on the retina, a countermovement can be perceived if one has been exposed to an intense, uniform movement stimulus for about 30 seconds and then looks at a stationary object. The effect can be perceived after looking at a waterfall for a long time, which is why one speaks of the waterfall illusion.

Individual evidence

  1. ↑ a b apparent movement. In: Dorsch, Lexikon der Psychologie, Hogrefe Verlag, Bern. MA Wirtz, accessed on May 8, 2019 .
  2. ↑ Frank Thömke: Eye Movement Disorders: A Clinical Guide for Neurologists. Georg Thieme Verlag, Stuttgart 2008, ISBN 978-3-13-128742-7 , p. 179 ( Google books ).
  3. ^ Walter S. Neff: A Critical Investigation of the Visual Apprehension of Movement. In: The American Journal of Psychology. University of Illinois Press, Volume 48, Number 1, 1936, pp 1-42 ( JSTOR 1415551 ).
  4. ↑ Siegmund Exner: About seeing movements and the theory of the compound eye. In: Session reports of the mathematical and natural science class of the Imperial Academy of Sciences, III. Department: Physiology, Anatomy and Theoretical Medicine. Volume 72, pp. 156-190., 1875 ( hdl: 2027 / coo.31924063807345 ).
  5. ↑ Max Wertheimer: Experimental studies on seeing movement. Zeitschrift für Psychologie, Volume 61, 1912, pp. 161-265 ( online , PDF 8.61 MB).
  6. ^ Howard C. Warren: Dictionary of Psychology. Routledge Revivals. New York 2018, ISBN 1-138-61628-1 , p. 54 ( Google books ). First published in 1935 by George Allen & Unwin Ltd.
  7. ^ Robert M. Steinman, Zygmunt Pizlob, Filip J. Pizlob: Phi is not beta, and why Wertheimer's discovery launched the Gestalt revolution. In: Vision Research. Volume 40, 2000, pp. 2257-2264 ( PMID 10927113 ).
  8. ↑ Andrew M. Colman: A Dictionary of Psychology. 4th Edition, Oxford University Press, Oxford 2015, ISBN 978-0-19-965768-1 , p. 87 ( Google books ).
  9. ↑ Joseph and Barbara Anderson: The Myth of Persistence of Vision Revisited. In: Journal of Film and Video. Volume 45, Number 1, 1993, pp. 3-12 ( JSTOR 20687993 ).
  10. ↑ Axel Larsen, Joyce E. Farrell, Claus Bundesen: Short- and long-range processes in visual apparent movement. In: Psychological Research. Volume 45, Number 1, 1983, pp. 11-18 ( online ).
  11. ^ Kerstin Witte: Basics of sports motor skills in the bachelor's degree. Springer Spektrum, Berlin 2018, ISBN 978-3-662-57867-4 , p. 66 ( Google books ).
  12. ↑ a b F. Schmidt; Gerhard Thews (ed.): Physiology of humans. 25th edition. Springer Verlag, Berlin 1993, ISBN 978-3-540-57104-9 , p. 281 ( Google books ).
  13. ↑ Herbert Hagendorf, Joseph Krummenacher, Hermann-Joseph Müller, Torsten Schubert: Perception and attention: general psychology for Bachelor. Springer Verlag, Berlin 2011, ISBN 978-3-642-12709-0 , p. 87 ( Google books ).