The American Cocker Spaniel is a breed of sporting dog. It is a spaniel type dog that is closely related to the English Cocker Spaniel; the two breeds diverged during the 20th century due to differing breed standards in the US and the UK. Known as the 'Merry Cocker', the American Cocker Spaniel breed standard defines the ideal dog of the breed as being 'equable in temperament with no suggestion of timidity.' The breed ranks 20th in Stanley Coren's The Intelligence of Dogs, a rating that indicates good 'Working or Obedience Intelligence', or trainability. IQ tests run on a variety of breeds in the 1950s and 1960s showed that the American Cocker performed the best when tested on its ability to show restraint and delayed response to a trigger, a trait which was put down to the breed's bred-in ability when hunting to freeze upon finding a bird before flushing it out on command.