One of the most salient features of dreams is the continual appearance of characters and the interactions between them. Personification appears as interactions between the dream self and other characters, and general patterns become more obvious than in waking life. Aspiring to simulate human reality, artificial intelligence research has found that practical intelligence does not work through logical deduction based on rules applied to separate units. Human reality is so complex that, even in the simplest events of daily life, it is not possible to list in advance all conceivable everyday events and combine them using logical rules. The abilities and skills of dream characters are not simply primitive deficient versions of the waking self. Dream characters’ abilities concerning thinking, perception, emotion, relational skills, mind-reading and levels of consciousness have been thoroughly studied. In a laboratory study, Swiss researchers Inge Strauch and Barbara Meier estimated that approximately 40 percent of dreams consist of thinking.