Perception of Weight Leads to Riddle's Answer

Everyone who thinks a pound of lead FEELS like it weighs the same as a pound of feathers, step forward.

Not so fast there…

The correct answer to the familiar, grade school riddle is that a pound of lead weighs the same as a pound of feathers, 16 ounces each.  But does a pound of lead actually FEEL heavier than a pound of feathers?  Yes, according to almost three quarters of blindfolded participants in a test of perception conducted by two Illinois State University Department of Psychology faculty members and a graduate student.

In the latest issue of the journal, Perception, assistant professors Jeffrey Wagman and Corinne Zimmerman, along with graduate student Christopher Sorric, are the authors of “Which feels heavier—a pound of lead or a pound of feathers?'' A potential perceptual basis of a cognitive riddle.

The researchers investigated whether the naive answer to the riddle might have a basis in perception. When blindfolded participants hefted a pound of lead and a pound of feathers - each contained in boxes of identical size, shape, and mass - they reported that the box containing the pound of lead felt heavier at a level above chance.  In fact, 73.9 percent of the participants chose the box of lead as heavier more often than the box of feathers.  Like the size–weight illusion, the naive answer to the riddle may reflect differences in how easily the objects can be controlled by muscular forces and not a perceptual or cognitive error.

“Our results seem consistent with findings that perception of heaviness is a function of an object’s dynamical symmetry – how its mass is distributed relative to where it is held,” the authors said.  When an object’s mass is not distributed symmetrically, more muscular force is required to control it, therefore it seems heavier than a symmetrically distributed object of the same weight.