When judging the weights of objects with a constant mass, there is a strong tendency for the larger objects to be perceived as lighter. This phenomenon is known as the size-weight illusion. The standard procedure in demonstrating this illusion is to have participants simultaneously hold and view the stimuli. In a recent article, however, Ellis and Lederman (1993) showed that the size-weight illusion does not necessarily rely on vision. Their results showed that, when participants held the stimuli, the strength of the illusion was the same whether or not they viewed the stimuli. Eliminating haptic information by having participants hold the object by a string resulted in a weakened illusion when participants viewed the stimuli and no illusion when they did not. From these results, they concluded that vision is sufficient but not necessary, while haptic information was concluded to be absolutely necessary (Ellis & Lederman, 1993).