Xref: utzoo sci.bio:4987 bionet.neuroscience:57
Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!dali.cs.montana.edu!uakari.primate.wisc.edu!sdd.hp.com!spool.mu.edu!snorkelwacker.mit.edu!bloom-beacon!eru!hagbard!sunic!mcsun!hp4nl!fwi.uva.nl!smagt
From: smagt@fwi.uva.nl (Patrick van der Smagt)
Newsgroups: sci.bio,bionet.neuroscience
Subject: do we perceive accelerations?
Keywords: time-to-contact, constant velocity
Message-ID: <1991May18.104301.17674@fwi.uva.nl>
Date: 18 May 91 10:43:01 GMT
Sender: news@fwi.uva.nl
Organization: FWI, University of Amsterdam
Lines: 26
Nntp-Posting-Host: wendy.fwi.uva.nl

I am trying to model motion in a quite wide perspective, but one
can narrow it down to hand-eye coordination.  When I look at 
biological mechanisms (e.g., myself), I get the impression that
motions are based on the fact that one assumes all moving
objects (including onself) to have a constant velocity.  
Correction for the fact that things have accelerations are
realised by fast sensory data processing.

Another indication for this assumption I find in Lee's article [1980]
in which  he invesigates time-to-contact.  He reports (in another
article, I believe) that subjects correctly estimate the time
left before an approaching object hits them, under the assumption
that the velocity of the object is constant.

What I am looking for are other indications for my assumption.
Do biological systems only `calculate' the first positional 
derivative from their sensory input?


						Patrick van der Smagt


References:
===========
D. N. Lee, The optic flow field: The foundation of vision.
Phil. Trans. R. Soc. Lond. B 290, pp. 169--179, 1980.