The inner tube effect

Ian M Thornton; Sunčica Zdravković; Dejan Todorović

doi:10.1177/20416695241249129

The inner tube effect

Iperception. 2024 May 8;15(3):20416695241249129. doi: 10.1177/20416695241249129. eCollection 2024 May-Jun.

Authors

Ian M Thornton¹, Sunčica Zdravković^{2

3}, Dejan Todorović³

Affiliations

¹ Department of Cognitive Science, Faculty of Media and Knowledge Sciences, University of Malta, Msida, Malta.
² Laboratory of Experimental Psychology, Department of Psychology, Faculty of Philosophy, University of Novi Sad, Novi Sad, Serbia.
³ Laboratory of Experimental Psychology, University of Belgrade, Belgrade, Serbia.

Abstract

We describe a novel size illusion in which targets appear to either shrink or grow when enclosed within a narrow tube. The direction of size change is determined by the contrast step between display elements. We first noticed this effect in the context of the dynamic "rocking line" illusion (RLI), but it can also be easily seen in completely static displays. As with the RLI, the overall scale of the display seems to play an important role. We provide an online, interactive demo, enabling the reader to explore the relevant parameter space.

Keywords: RLI; contrast illusions; rocking line illusion; size illusions; visual illusions.