A shadow of a doubt always fell on an idea of a threshold. Herbart came up with
a concept of ―a threshold of consciousness‖. Fechner‘s psychophysics uses a more
specific concept of ―sensory threshold‖. A theory of signal detection and subjective
psychophysics declare a threshold as a non-working idea. In the author‘s theory,
a threshold is a logically unavoidable consequence of the classification process.
This approach allows combining ideas of other approaches. There is an uncertainty principle
in the classification process: assigning a stimulus to a class is an automatic process which
makes no mistakes, however, when consciousness checks for mistakes, the representation of
a class itself becomes wider, its borders become uncertain. For sensory tasks, an uncertainty
principle states that when there is an absolute match between a stimulus and a standard,
we can not get a conscious evaluation of accuracy of the match. In other words, we pay for an
accurate match with uncertainty on evaluation of the accuracy