The apparent heaviness of colours

EARLY this century, E. Bullough 1 showed that some combinations of colours, one above the other, are chosen as more ‘natural’ than other combinations, which tend to look top heavy. Various methods of measuring the apparent weight of colours were subsequently devised: Bullough's preference method, tests in which the weight of coloured blocks was judged either visually or directly by hand 2,3,4 , and the ‘weighing’ of half-inch circles of coloured paper at either end of a simulated balance arm with an adjustable fulcrum 5 . There was general agreement that red and blue were the heaviest colours, yellow the lightest. But no statistical evaluation was used in the earlier work; and as the colours were surface-illuminated, the effect of colour was easily confounded with that of brightness. In fact, most investigators considered that brightness was probably a crucial factor. In the present study, an adaptation of Monroe's procedures, the effects of colour and brightness were investigated separately using larger transilluminated stimuli, with brightness carefully controlled. Our results show that the effect is independent of brightness. Coloured circles, equal in subjective brightness, differ considerably in apparent weight, while achromatic stimuli which differ in brightness are not consistently different in weight.