Not Alarmed but why?

[The Walkers]

Great thought.  When I was doing research in robot vision, we developed 1st
derivative and 2nd derivative motion detector algorithms, creating a 2-D
visual display mapped with highlighted regions where changes in an objects
position and acceleration were detected.  Of course, this first required
that we perform reliable object recognition over the visual field, which is
a hard enough problem to solve.  Fun stuff.  The bottom line is that we know
little about what insects actually "see".  One thing I have noticed is that
resting butterflies will often position themselves so that I can't see their
hindwings, making it virtually impossible to make a positive id without
netting them.  When I attempt to move my head (slowly and with constant
velocity) around to catch a better glimpse, the alighted butterfly will
often rotate itself on the flower or branch, maintaining its
_perpindicularity_ with respect to the direction of my gaze, continuing to
make itself virtually invisible.

Mark.
 
-------Original Message-------
 
From: fnkwp at uaf.edu
Date: 07/22/05 01:55:07
To: leps-l at lists.yale.edu
Subject: Re: Not Alarmed but why?
 
> Many times, when I spy the lep, I stop moving my head,
> and the lep takes off!  Clearly it knows it has been spotted.
 
It is possible that all the butterfly is doing is reacting to the
second derivative of the motion of your head--that is, to the
rate of change of the speed with which your head moves. Try
stopping the movement of your head gradually rather
than suddenly, and see if that helps.
 
   Ken Philip
 
 
 
 
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