Induced Movement

[quicktime width=”600″ height=”400″]http://anstislab.ucsd.edu/files/2012/11/NoFliesControl-4.mov[/quicktime]
No flies on Rama: The flying bugs illusion
These two bugs fly clockwise along circular orbits of the same size, in all 3 movies. They are in counter phase; one is at 6 o’clock when the other is at 12 o’clock.
[quicktime width=”600″ height=”400″]http://anstislab.ucsd.edu/files/2012/11/NoFlies.mov[/quicktime]
Now the right orbit looks twice as big as the left orbit, because the CW moving background is in phase with the LH orbit but in counter-phase with the RH orbit, which it enhances.
[quicktime width=”600″ height=”400″]http://anstislab.ucsd.edu/files/2012/11/NoFliesAspect.mov[/quicktime]
The orbits look elliptical, wide on the left and tall on the right.  The background moves CCW and is in counter-phase with the horizontal components of the left fly but the vertical components of the right fly.