shift invariance

[Lev Goldfarb]

On Wed, 6 Mar 1996, Edelman Shimon wrote:

> > Nazir, T.A. & O'Regan, J.K. (1990).
> > Some results on translation invariance in the human visual system.
> > Spatial Vision, 5, 81-100.
> 
>                                                               Nazir
> & O'Regan actually found evidence AGAINST translation invariance in
> human vision. They may have phrased the title conservatively to
> appease conservative reviewers... So, do not take the existence of
> translation invariance in biological vision for granted; heed well the
> cautionary note in Norberto's posting:
> 
> > Date: Mon, 4 Mar 1996 11:03:09 -0800 (PST)
> > From: Norberto Grzywacz <nmg at skivs.ski.org>
> 
> > A form of shift invariance appears to exist in cortical neurons of the 
> > anterior part of the superior temporal sulcus and of the inferior temporal 
> > cortex.  Neurons in these areas have large receptive fields, which can show 
> > considerable selectivity for what the stimulus is irrespective of exactly 
> > where it is in the visual field.  I would call this property "selectivity 
> > shift invariance," to contrast with "absolute shift invariance," which 
> > the cortex does not appear to have. 

Why would one want to invent such a strange name "selectivity shift 
invariance"?

If we 1) DO NOT FORGET that the biological systems have at their disposal
quite adequate means to extract symbolic (structural) representation right
from the very beginning and 2) FORGET about our inadequate numeric models,
then the question would not have arisen in the first place. Symbolic 
representations EMBODY shift invariance. We are completing a paper 
"Inductive Theory of Vision" that addresses these issues.


         Lev Goldfarb

http://wwwos2.cs.unb.ca/profs/goldfarb/goldfarb.htm