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OPTICAL ILLUSIONS have once been the key to the
psychology of vision - many configurations are known to
effect our normal perceptual mechanism of straightness,
parallellity, length, size, circularity, etc. (See
Davson (1962, p. 228) who collected a dozen examples,
Vernon (1962, title-page and p. 55, 56), and Tolansky
(1964), a book full of Illusions). The disturbing effect
of the simple figures and patterns are merely of
physiological nature, as if the sloping of curved lines
guide the eyes-to make unwanted scanning movements, or
that the retinal image processing mechanism is activated
in an unusual manner.
Most illusions are rather common as to the qualitative effect, the
quantitative aspect is probably cultural bound and varies considerably
(Hempenius et al, 1967).
Illusions attract attention, or is it the other way around?
Some illusions are rather attractive as patterns, fit for fashion,
whereas other patterns work provocating and even repulsive (Op-Art).
I is not clear in how far the optical illusions are of relevance
to photo-interpretation. Do the cleverly man-made patterns have
equivalent or vague analogues in our natural environment? It would
be interesting to hear of interpretors who discovered illusions of
this simple physiological type in aerial photographs. If they occur,
it is good to know the remedy against false interpretation: measure
the wanted property! Tolansky concludes his book with: "Not "Seeing",
but "Measuring" is believing"! (1964, p.155). See also Pseudo and
False Vision at the end of this paragraph, where it is combined with
these pure optical illusions.|
The remaining cards on the yellow square are selected SHAPE +
and arranged thus that the five facets reflect an PATTERN
Perception
increasing physiological influence from top to bottom:
Perception of Space & Movement, of Shape & Patterns, of DEPTH +
Depth & Heights, of Colour, and Pseudo & False Vision.
Obviously, any other arrangement has its advantages and
will also have chances to imprint the reader completely
wrong relations.
HEIGHT
Perception
COLOUR
Perception
ILLUSIONS
Optical
+ Pseudo
