What are the 7 causes of laughter in drama

i need to study to a test in drama and i need to know the 7 causes of laughter

Humorous, social, ignorance, anxiety, derision, apologetic, and tickling.

Source: http://au.answers.yahoo.com/question/index?qid=20091026131000AA9E0wO

actuallyexaggeration incongruity anticpation ambiguity recognition protection and relief

EXAGGERATION- inflated actions or movement, bigger than life
INCONGRUITY- contrasting visually/vocally (for example a skinny man next to a fat lady)
ANTICIPATION- building up for a laugh (banana peel is left of the floor, we wait for someone to fall, then at the end of the play someone slips on it)
AMBIGUITY- a play on words, a pun, a double meaning, or a disguise
RECOGNITION- spoofing about a common topic that we recognize
PROTECTION- brutal behaviour or slapstick, the audience laughs knowing that they are protected from the abuse or at the fact that no one is really getting hurt (pie in the face)
RELIEF- adding comedy to a dark or sad scence to lift the mood

The textbook The Stage and the School.