Hogwarts song, each student in turn is seated upon the stool in front of the rest of the student body. The Hat is placed on the student's head, whereupon it examines his or her mind and assigns them to one of the four Houses based on abilities, personality, and preferences. After the Sorting Ceremony, the students and teachers enjoy a feast, prepared by the Hogwarts house-elves. If Dumbledore is feeling cheerful, he will lead the students in singing the school song. Hogwarts is divided into four houses, each bearing the last name of its founder: Godric Gryffindor, Salazar Slytherin, Rowena Ravenclaw
Poltergeist and cognitive dynamics of percipients' interpretation of ambiguous stimuli". Psychologist Donovan Rawcliffe has written that almost all poltergeist cases that have been investigated turned out to be based on trickery, whilst the rest are attributable to psychological factors such as hallucinations. Attempts have also been made to scientifically explain poltergeist disturbances that have not been traced to fraud or psychological factors. Skeptic and magician Milbourne Christopher found that some cases of poltergeist activity can be attributed to unusual air currents, such as a 1957 case on Cape Cod where downdrafts from an uncovered chimney became strong enough to blow a