The moving dots are typically interpreted as lying on the surface of a rotating sphere.

The direction of rotation of the sphere is ambiguous.

The perceived direction of rotation tends to appear to flip every few seconds as the two competing interpretations vie for perceptual dominance.

Presenting the same stimulus intermittently rather than continuously tends to stabilize perception such that the rate of flipping is dramatically reduced.

Leopold, D.A., Wilke, M., Maier, A. & Logothetis, N.K. (2002)

 

Introducing the perception of "wobble" into the stimulus by subtly altering the dot trajectories again reduces the rate of perceptual alternations.

Blake, R., Sobel, K.V. & Gilroy, L.A.(2003)