Illusory shrinkage and growth: body-based rescaling affects the perception of size.

The notion that apparent sizes are perceived relative to the size of one's body is supported through the discovery of a new visual illusion. When graspable objects are magnified by magnifying goggles, they appear to shrink back to near-normal size when one's hand (also magnified) is placed next to them. When objects are "minified" by minifying goggles, the opposite occurs. The rescaling effect also occurred when participants who were trained in tool use viewed the tool next to the objects. However, this change in apparent size does not occur when familiar objects or someone else's hand is placed next to the magnified or minified object. Presumably, objects' apparent sizes shift closer to their actual sizes when one's hand is viewed because objects' sizes relative to the hand are the same with or without the goggles. These findings highlight the role of body scaling in size perception.