Asymmetry in Perceiving Object Orientation 

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Modifying Display

First click on the cube display

Background. Wire frame cubes are usually described as bistable — they spontaneously reverse in orientation as one views them.  It is common for collections of ambiguous objects to group into a single, shared interpretation.  In this case the cubes could (in principle) group by rotation e.g. all appear to rotate the same way, or to group by orientation.  Based on the results of a number of other displays one might expect one or the other of these to occur, and for all the cubes to stochastically switch interpretations more or less synchronously.

Display. Each cube is randomly assigned a coupling of rotation to orientation. Therefore a particular cube can be seen as tilted down while rotating left or as tilted up while rotating right. In general half the cubes have one pairing and half the other. Consequently, if your brain imposes grouping by rotation half the cubes will appear tilted up and half tilted down.  Alternatively, if you group by orientation, half the cubes will appear to rotate left and half right.

Axial Asymmetry. When the cubes rotate about a horizontal axis (tumbling up/down) there is no consistent global grouping by rotation or orientation.  Individual cubes are seen to perceptually alternate independently of one another.  However when the cubes rotate about a vertical axis, each cube appears to rather stably rotate in one direction.  That direction is determined by the visual system’s preference for interpreting each cube as tilted down or viewed-from-above.  In this case the cubes are not bistable, but rather strongly stable.

Interpretation.  The terrestrial environment is up/down asymmetric.  Objects sit on the ground and the lower half of the visual field contains more objects than the upper half field.  Objects in the lower half visual field are viewed from above.  Absent other information about orientation, the visual system assumes that an object with up/down orientational ambiguity is tilted down or viewed from above (like the majority of objects in our experience).

More information can be found in the paper:

PLoS ONE | 1 March 2010 | Volume 5 | Issue 3 | e9553

Dobbins & Grossmann (2010) Asymmetries in Perception of 3D Orientation. PLoS One, x: yy