In an 1899 lecture, University of Wyoming chemistry professor Emory Edmund Slosson announced that he wanted to see how rapidly a certain odor diffused through the air and asked students to raise their hands as soon as they could smell it. Then he poured distilled water over cotton, explaining that it was a chemical with a distinctly unusual odor. Within 15 seconds most of the students in the front row had raised their hands, and within a minute three quarters of the class had.

Similarly, University of California food scientist Michael O’Mahoney told a British TV and radio audience in 1978 that a certain sound frequency would induce the perception of an outdoorsy smell. This suggestion and some audiovisual prompts led hundreds of people to write in claiming they’d smelled something when the frequency was broadcast.

In The Scent of Desire (2009), Brown University psychologist Rachel Herz writes, “This media stunt shows how simply being told that an odor is ‘there’ can convince you that you are smelling something with all of its full-blown consequences.”

12/13/2023 UPDATE: It seems likely that Slosson is Edwin Emery Slosson — possibly Herz mistook his name. (Thanks, Charlotte.)