When the gorilla met the fingernails on a chalkboard

This study tells what happened when two Ig Nobel Prize-winning experiments were combined:

Inattentional blindness for a noxious multimodal stimulus,” Joseph F. Wayand, Daniel T. Levin and D. Alexander Varakin, American Journal of Psychology, vol. 118, no. 3, Fall 2005, pp. 339-52. The authors, at DePauw University and at Vanderbilt University, explain:

“Previous research has shown that people can miss salient stimuli outside the focus of their attention. This phenomenon, called inattentional blindness, typically is observed when people are given a task requiring them to focus their attention on one aspect of a complex visual scene. While participants are doing this task, an unexpected stimulus appears, and participants’ awareness of it is tested shortly thereafter. In the present experiments, noxious bimodal stimuli were used as a test case to measure the strength of inattentional blindness. We tested whether participants would notice a person enter a scene and scratch her fingernails down a chalkboard (thus making a sound called a “gride”). A large proportion of participants failed to detect this event even when the noxious audio associated with it was strengthened and isolated in time from surrounding noises.”

These are the Ig-winning achievements upon which it builds. Both are explicitly cited in the Wayand/Levin/Varakin study:

GORILLA: The 2004 Ig Nobel Prize in psychology was awarded to  Daniel Simons and Christopher Chabris, for demonstrating that when people pay close attention to something, it’s all too easy to overlook anything else — even a woman in a gorilla suit. [REFERENCE: “Gorillas in Our Midst,” Daniel J. Simons and Christopher F. Chabris, vol. 28, Perception, 1999, pages 1059-74.]

FINGERNAILS ON A BLACKBOARD: The 2006 Ig Nobel Prize in acoustics was awarded to D. Lynn HalpernRandolph Blake and James Hillenbrand for conducting experiments to learn why people dislike the sound of fingernails scraping on a blackboard. [“Psychoacoustics of a Chilling Sound,” D. Lynn Halpern, Randolph Blake and James Hillenbrand, Perception and Psychophysics, vol. 39,1986, pp. 77-80.]

BONUS: Mo Costandi puts it all in context

BONUS: Dan Simons and the gorilla experiment: