Abstract
This is the first report of a mutual
interference between luminance and numerical value in magnitude judgments.
Instead of manipulating the physical size of compared numbers, which is the
traditional approach in size congruity studies, luminance levels were
manipulated. The results yielded the classical congruity effect. Participants
took more time to process numerically larger numbers when they were brighter
than when they were darker, and more time to process a darker number when its
numerical value was smaller than when it was larger. On the basis of
neurophysiological studies of magnitude comparison and interference between
semantic and physical information, it is proposed that the processing of
semantic and physical magnitude information is carried out by a shared brain
structure. It is suggested that this brain area, the left intraparietal sulcus,
subserves various comparison processes by representing various quantities on an
amodal magnitude scale.