  Support agents that help users in their daily lives need to take into account
not only the user's characteristics, but also the social situation of the user.
Existing work on including social context uses some type of situation cue as an
input to information processing techniques in order to assess the expected
behavior of the user. However, research shows that it is important to also
determine the meaning of a situation, a step which we refer to as social
situation comprehension. We propose using psychological characteristics of
situations, which have been proposed in social science for ascribing meaning to
situations, as the basis for social situation comprehension. Using data from
user studies, we evaluate this proposal from two perspectives. First, from a
technical perspective, we show that psychological characteristics of situations
can be used as input to predict the priority of social situations, and that
psychological characteristics of situations can be predicted from the features
of a social situation. Second, we investigate the role of the comprehension
step in human-machine meaning making. We show that psychological
characteristics can be successfully used as a basis for explanations given to
users about the decisions of an agenda management personal assistant agent.
