TY - JOUR AU - Welf Alfred Kreiner PY - 2025 DA - 2025/10/24 TI - Intensity of Visual Illusions Calculated from Geometric Parameters of the Stimulus JO - Japan Journal of Research VL - 6 IS - 12 AB - The angle subtended by the consciously perceived image – the active angle – corresponds to a certain area on the retina. Hypothetically, this section on the retina is displayed on an “internal visual memory screen” that is always the same size. Several of the geometrical-optical illusions are attributed to a changing active angle adapted to the extent of the stimulus. An example is given, and an algebraic expression is derived from a model. In this way, the intensity of the illusion can be traced back to the dimensions of the geometric elements of the stimulus. The visual sense is compared to a data communication channel. Its limited capacity may occasionally lead to a reduction in the active angle, enabling better resolution. This can make a celestial body appear larger. It occurs automatically close to the horizon. Other reasons are given that can reduce the active angle. Depictions of celestial bodies in paintings indicate that the active angle can vary greatly from case to case. SN - 2690-8077 UR - https://dx.doi.org/10.33425/2690-8077.1218 DO - 10.33425/2690-8077.1218