Julian O'Dea:

> The problem with the new Esch et al. theory is that if it
> is true that optic flow is the basis for distance estimation,
> this demands great accuracy as regards direction.


Jim Fischer:

I'd like an explanation of how an estimate of a distance
makes "demands" upon an estimate of direction.


Julian O'Dea: If you refer to the recent Esch et al. paper
in "Nature", you will see that the authors themselves,
despite being dance language believers, see the problem.
As their data show, the "information" on distance contained
in the dance varies hugely depending on the direction to the
resources. So, the authors write, "... there must be a high
selection pressure to ensure that a dance signals the
direction of the food source as precisely as possible."
However there is evidence that direction information is
also not accurate (Vadas, 1994):

Vadas, R.L. 1994.  The anatomy of an ecological controversy:
honey-bee searching behaviour.  Oikos 69: 158-166 and at: http://www.beesource.com/pov/wenner/oikos94.htm