  Increasing experimental evidence shows that humans combine concepts in a way
that violates the rules of classical logic and probability theory. On the other
hand, mathematical models inspired by the formalism of quantum theory are in
accordance with data on concepts and their combinations. In this paper, we
investigate a novel type of concept combination were a number is combined with
a noun, e.g., `Eleven Animals. Our aim is to study 'conceptual identity' and
the effects of 'indistinguishability' - in the combination 'Eleven Animals',
the 'animals' are identical and indistinguishable - on the mechanisms of
conceptual combination. We perform experiments on human subjects and find
significant evidence of deviation from the predictions of classical statistical
theories, more specifically deviations with respect to Maxwell-Boltzmann
statistics. This deviation is of the 'same type' of the deviation of quantum
mechanical from classical mechanical statistics, due to indistinguishability of
microscopic quantum particles, i.e we find convincing evidence of the presence
of Bose-Einstein statistics. We also present preliminary promising evidence of
this phenomenon in a web-based study.
