Re: What is this visual cliff phenomenon?

Devi (
Fri, 3 Jul 98 11:26:32 +0100


>Basically, it was concluded from this that depth perception was
>present in infants at a very early age.
>If you consider the above, and then consider the posting by Jim
>Mancuso, a few days ago, you will see that he too was interested by
>this notion. But when he tried to replicate Gibson and Walk's study,
>he was unable to get the same results.

I seem to recall that the _behaviour_ appeared concomitantly with the
animal's developing ability to locomote intentionally (Walk & Gibson
1961); on the other hand, it proved problematic to test the assertion
that "depth perception develops concomitantly with purposeful locomotion"
because one couldn't run the experimental procedure properly until a
degree of locomotion had developed. Distinguishing between intended and
accidental movement onto the cliff can be difficult: e.g. human babies
who can't locomote but are sitting up find it easier to fall backwards
than forwards; so I wonder if anyone controlled for which way the baby
was facing (seeing the cliff versus not seeing it) at the age when they
were falling over rather than purposefully crawling? Presence of nappy (a
more stable base) or its absence?

As always, so much depends on the minutiae of Gibson's, or Jim Mancuso's,
experimental procedure. At the heart of that positivist standby,
"operational definition of variables", lies the constructivist matter of
how meaning is constructed...

And while we're on the subject of "classic experiments" that everyone of
a certain age remembers...
What about the Kitten Carousel? Who says that experimental psychologists
aren't sloppy sentimentalists at heart?

Have a nice summer!



Walk, R.D. & Gibson, E.J. "A comparative and analytical study of visual
depth perception" _Psychological Monographs_ 1961, 75, 519.