Illusion - Is Seeing Really Believing?/Illusion - Is Seeing Really Believing (1998)(Marshall Media)[Mac-PC].iso/pc/illusion/rock_fie.cxt/00321_Field_321.txt

Text File | 1996-12-31 | 1KB | 46 lines

The Delboeuf illusion: the outer
circle in the left figure
assimilates to the smaller
circle it surrounds and the
inner circle in the right figure
assimilates to the larger circle
around it so that the two circles
to be compared appear unequal
in size.

    Assimilation implies the
opposite process--that is, a
tendency to perceive an object
as including or incorporating
the properties of certain
background elements. A good
example is the Delboeuf
illusion, shown in the
illustration here. In that
illustration, the inner circle to
the right looks larger than the
outer circle to the left although
both are the same size. One
might say that this occurs
because the inner circle on the
right assimilates to its larger
surrounding circle, while the
outer circle on the left
assimilates to the smaller
circle it surrounds. In the case
of the Ponzo illusion, the upper
line can be said to assimilate to
the inducing lines so that it
tends to "stretch," to appear as
wide as the distance between
the converging lines at the
same height in the field. Thus,
the effect of contrast is to
diminish the perceived size of
the lower line, and the effect
of assimilation is to increase
the perceived size of the upper
line. Note that this explanation
does not entail either depth
perception or constancy.