Several measures of uncertainty, in its various forms of nonspecificit
y, conflict, and fuzziness, valid both in finite and infinite domains
are investigated. It is argued that dimensionless measures, relating u
ncertainty situations to the information content of their respective u
niversal sets, can capture uncertainty efficiently both in finite and
infinite domains. These measures are also considered more intuitive. T
o establish them, a more general approach to uncertainty measures is d
eveloped. After this, the utilization of these measures is exemplified
in the measurement of the uncertainty content of evidence sets. These
interval-based set structures, defined through evidence theory, are s
hown to possess ideal characteristics for the modeling of human cognit
ive categorization processes, within a constructivist framework.