The Center of Gravity Affects Weight Perception: Findings from the Koseleff Illusion

Weight perception is primarily determined by an object’s actual mass but is modulated by several other factors. A representative example of this is the Koseleff illusion, a type of size-weight illusion in which larger objects are perceived as lighter than smaller ones, even when both have the same mass. However, in prior studies of this illusion, the objects to be lifted were enlarged by stacking another item on top, thereby altering not only their visual size but also their center of gravity. Some of these studies have suggested that the center of gravity may independently affect weight perception. This study tested this possibility by examining the Koseleff illusion without visual cues. As a result, a Koseleff-like illusion was observed even without visual input. These findings suggest that weight perception is shaped by the interaction between visual and non-visual factors, with the center of gravity playing a key role.