Social interaction is conducted via what Berne called transactions. A transactional stimulus from one person results in a transactional response from another. In complementary transactions, needs are expressed and met, such as in problem solving (Adult-Adult), in mutual play (Child-Child or Parent-Child), or when two people gossip (Parent-Parent). Problems arise when a crossed transaction occurs. Take, for example, the stimulus “Do you know where my glasses are?” The response “Why don’t you look after your own things instead of always relying on me?” represents a controlling Parent response to an Adult stimulus.