Excerpt from
L.Kleine-Horst: Empiristic theory of visual gestalt perception. Hierarchy and interactions of visual functions. (ETVG), Part 5, III

Experiencing the same stimulus at different levels.

The quantity, orientation, and form factors have been described as entities producing specific visual qualities. As these gestalt factors are actualized "from the bottom up", such as with increasing direction of attention, their specific qualities are introduced into the percept in succession, according to the height of the level they are located at. Thus one and the same stimulus appears different depending on the level up to which the actualization has proceeded. Although "real" processes of such an "actual genesis" is the main topic of the next Part, here a "virtual" actual genesis of a rectangle will be shown to elucidate the particular contribution of each of the fifth-to-tenth level factors to the visual experience of a stimulus.

With only the gestalt factors Pml to Fl, a rectangle will be experienced as a "figure" (in its outfield), i.e. as a percept which does not show any other qualities than those constituted by the factors Pml to Fl; the rectangle thus appears as a spot with a "circlelike" contour. Even the term "circlelike" can lead to misunderstandings if one describes the contour with any of the geometric terms learned in school, as the "totality of locations that have equal distances from one point". However, "equal" is a quality that does not belong to the fifth (Fl) level, and thus is not perceivable with actualization of only the factors up to and including Fl.

Strictly speaking, a "figure" can be seen with factors up to and including Fl only when the gaze is already focused on the stimulus, here: the rectangle. When presented extrafoveally, the rectangle cannot be seen at the fifth level, but only with the additional actualization of the sixth factor Q, with at least the value Q1. By "normal" oculomotor (and other) movements, the rectangle will then project itself onto the fovea, and will be experienced at the F-level as a disklike spot. At the next levels, the rectangle appears as an "ellipse" with the help of the factor E, whereas with the factors V, H, and T a certain orientation of the ellipse will be experienced as well. This requires, however, an increase in  the actualization of the factor Q up to value Q2. At this level and value, neither the fourness nor the straightness of the sides of the rectangle can be seen, nor the linkages between the sides, nor other qualities. We learned in school to designate a figure of a particular, and well definable, "form" an "ellipse". But note, that this definition, and designation, has the actualization of the entire visual factor hierarchy as a prerequisite. When the hierarchy is only partially actualized, we encounter other percepts. When the hierarchy is actualized only up to and including the eighth level, and we see that which we have learned to designate as an "ellipse", we are not at all perceiving a figure that is con- structed of the qualities and relationships we use in geometry (as already shown in the case of "circle"). Thus, our percept "ellipse" of the rectangle stimulus is as little "round" as a circle at the Fl-level, since "round" and "curved" are qualities produced by the higher-level factor "straightness" (S). A rectangle appears at the eighth level only as an "elongated, extended figure" in a certain orientation.

Only at the ninth level, with actualization of both factor Q at value Q3 and factor S, can the straightness of the sides be seen (at least of three sides, as perceiving four sides requires value Q4). We thus would perceive also a figure with three, instead of four, corners. We do not even perceive "pointed corners", as each of them is constituted of two oriented extensions (lines or bars, for example) that are linked to each other with an end. But we can perceive a "figure with three smooth corners", where per corner two extensions that are partially straight merge.

The rectangle "in its full geometric array" can be seen only with the additional actualization of the factor "rectangularity/parallelism". Now an elongated (E) figure (Pml - Fl) is seen possessing four (Q4) straight (S) sides (Ll), of which each two ends are rectangularly (R+) connected, and each two sides are parallelly (R-) oriented (V, H, T), and the parallel sides are of equal length (M), whereas the rectuangularly connected sides are of different length (M). In this description of the percept "rectangle" only such qualities are used, and of each their full set, that are defined in the ETVG as constituting a static, two-dimensional figure.

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