Center of mass perception and inertial frames of reference

Abstract

Center of mass perception was investigated by varying the shape, size, and orientation of planar objects. Shape was manipulated to investigate symmetries as information. The number of reflective symmetry axes, the amount of rotational symmetry, and the presence of radial symmetry were varied. Orientation affected systematic errors. Judgments tended to undershoot the center of mass. Random errors increased with size and decreased with symmetry. Size had no effect on random errors for maximally symmetric objects, although orientation did. The spatial distributions of judgments were elliptical. Distribution axes were found to align with the principle moments of inertia. Major axes tended to align with gravity in maximally symmetric objects. A functional and physical account was given in terms of the repercussions of error. Overall, judgments were very accurate.

The locus of “memory displacement” is at least partially perceptual: Effects of velocity, expectation, friction, memory averaging, and weight

“…Rather, distortions in the perception of the center of a stimulus occur. The downward bias is consistent with previous reports of judgments of the center of gravity (Bingham & Muchisky, 1993a,1993b. However, the important thing to note here is that they are observed at a perceptual level, and not at a higher level cognitive stage.…”

Perceiving the Center of Three-Body Displays: The Role of Size-Ratio, Symmetry, Elongation, and Gravity

“…Previous work finds that errors increase with an increase in elongation [3]. We also obtained results that can be interpreted according to elongation, although in our case elongation is an inferred property.…”

“…When the equilateral was rotated, this effect disappeared, suggesting that it was alignment with perceived gravitational vertical that induced the effect. An increase in errors when the major axis of reflectional symmetry was vertical is another result [3]. The response distribution in this case aligned with both the symmetry and perceived gravitational axes.…”

“…When these distributions were very elongated, they closely approximated the major orientation axis of the shape. In addition, there has been an increase in center estimation error with an increase in axis length [3].…”

“…It can be used for grasping and manipulation of objects. Participants will grasp wooden planar shapes using tongs at their center of mass [3]. A perceptual center can be calculated as a compact way of representing the location of an object.…”