Relationship Between Center of Mass and the Body Tilt Illusion

The body tilt illusion relates to one’s exaggerated perception of body tilt angle in comparison to reality. People tend to overestimate this illusion and feel that they are tilted at 45º when they are tilted less than 45º in reality. This illusion increases with lack of sensory cues and decreases when sensory cues are added. In the present study, distortion in the perception of body tilt was examined as a function of center of mass. There are gender differences in regards to where one’s center of mass lies on their body, with females having a lower center of mass on average compared to males (Elert, 2005). We used a human-sized 3D gyroscope to test participants’ experience of the body tilt illusion. The findings support that perception of body tilt is multisensory and that visual information as well as the tilting plane affects the magnitude of the illusion. This is consistent with the illusion being functional for helping people keep their balance. Yet, we did not find significant differences in the size of the illusion due to differences in center of mass. The pattern of findings supports that the body tilt illusion is relatively universal, and likely functional, but does not vary much due to individual body shape differences like center of mass.