Helsinki Institute for Information Technology HIIT, University of Helsinki, Helsinki, Finland. antti.honkela@hiit.fi|Helsinki Institute for Information Technology HIIT, University of Helsinki, Helsinki, Finland. antti.honkela@hiit.fi|Helsinki Institute for Information Technology HIIT, University of Helsinki, Helsinki, Finland. antti.honkela@hiit.fi|Helsinki Institute for Information Technology HIIT, University of Helsinki, Helsinki, Finland. antti.honkela@hiit.fi|Helsinki Institute for Information Technology HIIT, University of Helsinki, Helsinki, Finland. antti.honkela@hiit.fi