References to these essays must cite them explicitly as unpublished manuscripts. Psychology is plagued by what I call confusion-creating experiments. These are procedures that yield curious and repeatable data but that are worthless or worse since they promote and perpetrate confusion. The use of windows , apertures , frames , or holes in setting up experiments on visual perception is very tricky, and when relative motion is added to the situation it is even more tricky.
E is interested in O's perception of what is behind the aperture .
This is demonstrated by Michotte's method of producing optical motions in an array, a method which entails no form perception whatever. When the aperture becomes a mere slit in the screen the only information in the optic array is for spots moving along the slit. Moreover the history of research on the apparent direction of the motion of moving stripes in a window, as this depends on the shape of the occluding edges of the window, the frame, should also make these investigators realize that you cannot expect to move an aperture over a picture, or move a picture behind an aperture, without providing anomalies in the perception of the picture. These anomalies have nothing whatever to do with the perception of form as such. There are a whole set of muddles that this mischief-making experiment encourages.