The Influence of Directionality on the Giovanelli Illusion
Authors: Michele Sinico
In the Giovanelli illusion, some collinear dots appear misaligned, when each dot lies within a circle and the circles are not collinear. In this illusion, the role of the frame of reference, determined by the circles, is considered a crucial factor. Three experiments were carried out to study the influence of directionality of the circles on the misalignment. The adjustment method was used. Participants changed the orthogonal position of each dot, from the left to the right of the sequence, until a collinear sequence of dots was achieved. The first experiment verified the illusory effect of the misalignment. In the second experiment, the influence of two different directionalities of the circles (-0.58° and +0.58°) on the misalignment was tested. The results show an over-normalization on the sequences of the dots. The third experiment tested the misalignment of the dots without any inclination of the sequence of circles (0°). Only a local illusory effect was found. These results demonstrate that the directionality of the circles, as a global factor, can increase the misalignment. The findings also indicate that directionality and the frame of reference are independent factors in explaining the Giovanelli illusion.
Digital Object Identifier (DOI): doi.org/10.5281/zenodo.2363139Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 573
 M. Wertheimer. Untersuchungen zur Lehre von der Gestalt. II. Psychologische Forschung, 4, 301-350, 1923. Eng. Trans. Laws of Organization in Perceptual Forms. In Ellis, W. (1938). A source book of Gestalt psychology (pp. 71-88). London: Routledge & Kegan Paul.
 W. Metzger. Gesetze des Sehens. Krankfurt-am-Main: Kramer, 1936. Eng. Trans. Laws of Seeing. Cambridge (Massachusetts): The MIT Press, 2006
 G. Kanizsa. Organization in Vision. Essays on Gestalt Perception. New York: Praeger Publishers, 1979.
 M. Sinico. Explanation in experimental phenomenology: The nomic, deterministic and modal domain. Gestalt Theory, 32, 3, 293–306, 2010.
 G. Giovanelli. Stati di tensione e di equilibrio nel campo percettivo. Rivista di Psicologia, 60, 327–335, 1966.
 G. Kanizsa. “Errore del gestaltista” e altri errori da aspettativa. Rivista di Psicologia, 66, 3-18, 1972
 B. Pinna & L. Sirigu. The accentuation principle of figure–ground segregation and the downbeat illusion. Acta Psychologica, 170, 32–57, 2016.
 W. Metzger. Psychologie. Steinkopff Verlag: Darmstadt, 1963.
 P. Bozzi. Direzionalità e organizzazione interna di una figura. Memorie della Accademia Patavina di SS.LL.AA., Classe di Scienze Morali, Lettere ed Arti, LXXXI, 1968-69. (See also: P. Bozzi. Experimenta in Visu. Ricerche sulla Percezione. Milano: Guerrini, 1993.
 T. Kenet, D. Bibitchkov, M. Tsodyks, A. Grinvald & A. Arieli, A. Spontaneously emerging cortical representations of visual attributes. Nature, 425, 954-956, 2003.
 G. Giovanelli & M. Sinico. The role of directionality on the Giovanelli’s Illusion. Perception, volume 34, supplement, London, p. 26, 2005.
 J.T. Enns & S. Coren. The box alignment illusion: An orientation illusion induced by pictorial depth. Perception & Psychophysics. 58, 8, 1163-1174, 1995.
 J. Yang & A. Schwaninger. Yang’s iris illusion: External contour causes length-assimilation illusions. Japanese Psychological Research, 53, 1, 15–29, 2011.