As a complement to the concentration on negative states in welfare science, scientists are
increasingly considering the desirability of measuring positive outcomes. Since evaluation of
an animal's mental state is a critical goal for welfare assessment, considerations of both
positive feelings (what an animal “likes”) and resources that an animal is motivated to obtain
(what an animal “wants”) appear to be important. However, since animals may make choices
that are not in their long-term interests, an assessment of positive feelings and resources�…