Why do some people just can’t stand it when you scratch a chalkboard with your nails?

Answer

Hi Christophe,

I don’t think there is a good explanation for it, but some research has already been done: Aures 1984; Halpern, Blake and Hillenbrand 1986; Vschillo 2003; Neumann & Waters 2006; cox 2008; Oehler and Reuter, 2011.

Several avenues are explored in those studies, but none of them have been exclusively proven:

• the sound would resemble a primate alarm cry, evoking an instinctive survival response
• the sound would have frequencies close to the natural resonance of the human inner ear, and be amplified there (making our ear a shrill whistle)
• it can be a culturally learned response, which some people have and others don’t, and is stronger if people know how the sound was created.

Halpern, Blake and Hillenbrand’s research won the Ignobel Prize (20 years after publication), a teasing tribute to research that at first glance seems ridiculous, but is actually interesting.

Interestingly, Australian researchers also looked at whether the sound used in human learning experiments was an ethically justifiable pain stimulus (where weak electric shocks or very loud sounds were used in the past, which can be harmful).

Lynn Halpern, Randolph Blake, & James Hillenbrand (1986). “Psychoacoustics of a chilling sound” in Perception and Psychophysics. Psychonomic Society. pp. 77–80.