An episode of the BBC series Horizon from 1975 examines the psychology of music, exploring how music of any type can evoke certain feelings, and how a specific combination of chords, known as the I-IV-V (1-4-5) progression, is often referred to as “the three chord trick” behind hit songs.

Using examples from the Beatles to Bach, Horizon looks at the factors – physical, psychological and social – that make up the magic of music. Just how far can we succumb to the influence of music?

They also addressed Muzak, which gained popularity during this period. It had its detractors, who claimed it was manipulative, and its defenders, who disagreed.

Now in terms of music being manipulative. It is no more manipulative than if you have air conditioning in an office so someone is able to work better… I don’t think that it’s any more manipulative than if you have a nice clean environment.