The effect of absolute size on the separability of the dimensions of size and brightness

Stimulus dimensions of size and brightness were used in an experimental paradigm which determines whether redundant dimensions are discriminated more easily than single dimensions and whether selective attention to dimensions is possible. Four different absolute sizes were used. The results show that selective attention is possible and that there is no facilitation of discrimination with redundant dimensions, and that these results are uninfluenced by absolute size. Thus, size and brightness are separable dimensions for all absolute sizes tested.