Max Wertheimer
"The basic thesis of gestalt theory might be formulated thus:
there are contexts in which what is happening in the whole cannot be deduced from the characteristics of the separate pieces, but conversely; what happens to a part of the whole is, in clearcut cases, determined by the laws of the inner structure of its whole."
Max Wertheimer,
Gestalt theory.
Social Research, 11 (translation of lecture at the Kant Society, Berlin, 1924).
http://www.geocities.com/hotsprings/8646/
"Two lines were exposed in two different places on the face of the tachistoscope. Each exposure lasted a very short time and was separated from the next exposure by varying lengths of time. If there was too long a time between the exposures, the subject would see the lines successively. If the time was too short, he would see the lines simultaneously. However, if the time interval between the exposures was at an optimal length, the subject saw, not two lines successively or simultaneously, but one line move from one place to another. The experience is that of a single line which visibly moved, despite the fact that actually there are two successively exposed stationary lines separated by an interval of time. Variations, such as exposing a vertical line followed by a horizontal line, for which the observer saw a line swinging around through ninety degrees, gave the same result-an impression of motion of lines.
This apparent movement Wertheimer called phi phenomenon.
Sometimes an observer reported movement alone, with no line being seen to move. Movement without the lines being experienced at all, he called "pure phi." Although the name was new, the phenomenon itself had been known for many years. This seemingly trivial verification of what was known was to launch another new movement in psychology."
http://educ.southern.edu/tour/who/pioneers/wertheimer.html
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