In mental spaces theory, mental spaces are set up by space builders which are linguistic units that either prompt for the construction of a new mental space or shift attention back and forth between previously constructed mental spaces. Space builders can be expressions like prepositional phrases (in 1966, at the shop, in Fred's mind's eye, from their point of view), adverbs (really, probably, possibly, theoretically), connectives (if... then...; either... or ...) and subject-verb combinations that are followed by an embedded sentence (Fred believes (Mary likes bananas), Mary hopes ..., Susan states ...). What is special about space builders is that they require the hearer to 'set up' a scenario beyond the 'here and now', whether this scenario reflects past or future reality, reality in some other location, hypothetical situations, situations that reflect ideas and beliefs, and so on.