Abstract: 100 normal adult subjects, the two sexes being equally represented, were employed in a lifting-weight experiment. The requirement was to select a weight from a series of comparison cylinders to match a particular standard cylinder in perceived heaviness. The comparison weights are all of the same dimensions (4 cm in height and 2.5cm in diameter), but of different weight. There were two standard weights, all of 50 grams but of different dimensions. The larger standard is 4cm in height and 6.5cm in diameter, and the smaller one is 4cm and 1.5 cm respectively.The subjects used their right and left hands separately in making the above mentioned equal-heaviness matchings. A small group of left-handed persons was included in the experimental subjects.It was found: 1) that the size-weight illusion manifests without exception in every subject's comparisons of weight cylinders of different dimensions; 2) that on the whole the size-weight illusion shows no great difference with respect to the two sexes, but in judging the heaviness of the weights the female subjects have a slight hut consistent tendency to more strongly overestimate the smaller and underestimate the larger cylinders; 3) that the left-handed subjects' preferred hand tends to underestimate heaviness, but the size-weight illusion does not suffer any significant change because of this tendency of underestimation.

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