** FILE ** Actress Janet Leigh appears as Marion Crane in the famous shower scene in Alfred Hitchcock's 1960 classic thriller "Psycho." Leigh died Sunday Oct. 3, 2004 at her home in Beverly Hills California according to a spokeswoman. She was 77. (AP Photo/File, HO)

London - The screech of violins helped make the Psycho shower scene one of the scariest of all time. Now scientists think they know why.

They say that distorted and jarring music reminds us of the calls made by animals in distress and “brings out the animal in us” by putting us on high alert for threats such as predators.

The study played a series of music clips by two composers to volunteers. Some of the tunes were likened to “elevator music” and were designed to have little effect on the emotions.

Others had distorted sounds similar to when instruments strain at the top of their range. These were described as being more exciting, the journal Biology Letters reports.

Greg Bryant, of the University of California, Los Angeles, said: “Composers have intuitive knowledge of what sounds scary. What they don’t realise is they’re exploiting our predispositions to... bring out the animal in us.” - Daily Mail