Adaptation to Weight Transformation in Water

Abstract

Objects weigh less in water than in air clue to the upthrust of the water. Swimmers might be expected to adapt to this transformation, perceiving objects as heavier at the end of a swimming period than at the start. Fourteen subjects wore required to estimate the weights of a set of tins in air, and of another set in water, before and after a 10 rain swimming period. Both sets of tins were judged significantly heavier on the second test, showing the expected adaptation and aftereffect. A second experiment comparing the estimated weights of tins in air and water showed that viscous drag did not increase apparent weight in water; but that some subjects made an intellectual correction for the loss of weight in water. Intellectual corrections may account for the appearance of ’ weight constancy ’ on entering the water, but cannot account for adaptation or aftereffect.