Metaphors and analogies can be helpful for people when they have to learn or learn to use something. Some empirical studies into the effect of metaphors in software manuals showed a positive influence on computer task performance, although this influence proved to be a conditional one. A necessary condition must be that readers understand the metaphor used; readers must have knowledge about its source domain. The most understandable concept for all humans seems to be a human being; the metaphor with human beings as a source domain is called personification or anthropomorphism. Up to now, no coherent theory has been available about linguistic expressions that can be labeled as anthropomorphism, and no empirical data have been gathered about expressions in software manuals that are perceived as such by readers. Therefore, an explorative experiment with real manual material was carried out. Expressions suggesting that computers or programs have feelings or an affective relationship to the user, that they are able to perform non-routine (mental) activities and communicate their intentions through human language use, appear to be perceived as anthropomorphistic. Such expressions might help readers to use a computer (program) more easily.