Re: weighting depth clues

[T3D john bercovitz <bercov@xxxxxxxxxxx>]

Scott Langill writes:
 
> The visual cliff experiments (where infant creatures avoid the part
> of a surface painted with gradients making it look further away or
> deeper) have shown that some depth perception mechanisms are innate (at
> least in precocious species) and may be the result of a specific type
> of neuron rather than a higher order mental judgement (like your car).
 
The visual cliff experiments I saw used a piece of acrylic plastic
(Plexiglas, Lucite, Perspex, whatever) joined to the edge of a table.  
The infant stopped where the acrylic met the table because he could 
see that the floor was a few feet below the acrylic.  Interesting that 
some pretty advanced stuff is hardwired.
 
Comparing cars and faces, I had both in the lecture.  I shot with 
lenses that were correct for the audience's seating distance, 1/3 
of correct, and 3 times correct length.  The faces shot with too 
long or too short looked fairly normal in spite of the geometric 
reconstruction being _way_ out of whack.  The cars looked much less 
normal.  I think this goes along with the difficulty of seeing a 
pseudo face.  Perhaps the face is a hardwired model?
 
John B

PS: I'll be off the air until Friday.


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