[From Bill Powers (940607.1215 MDT)]
My mistake. The scalar perceptions (leftness and aboveness) DO need
to be compensated for tilt or DO need to be derotated. This may
actually involve using signals for head/body orientation to apply a
rotation matrix to the x-y position signals, redefining "up". This
mental rotation has been inferred from experiments. In Steven
Pinker's book "The Language Instinct," Pinker reports a neat tidbit
from his reading of the literature: the mean speed of de-rotation is
about 56 RPM!
Pinker's book, by the way, is a masterpiece of writing. Recommended.
Bill P