The size-distance paradox is a cognitive phenomenon

The perceived size of a fixated object is known to be a function of the per ceived fixation distance. The size-distance paradox has been posited as evi dence that the perceived distance of a fixated object is, in turn, influenc ed by the object's perceived size. If this is correct then it challenges a widely accepted account (modified weak fusion) of how the nervous system co mbines multiple sources of information. We hypothesised that the influence of perceived size on the perception of distance is likely to be restricted to conscious perceptual judgements. If our hypothesis is correct then the s ize-distance paradox should not be observed when observers make action-base d distance judgements. In line with this expectation we observed the size-d istance paradox when participants made verbal reports on target distance bu t found no paradoxical judgements in a group who were asked to point at the target. We therefore suggest that the size-distance paradox should not be taken as evidence that perceived size feeds back into distance perception.