We're instructed to put the papers in our mouths. As my saliva wets it, a nasty bitterness blooms. My neighbor, too, is making a face that says yuck. Then Bartoshuk asks for a show of hands. This routine never fails to impress an audience.
Jaws go slack as hands shoot up in answer to both questions.
A lab colleague, who must have swallowed some of the airborne crystals, noted how bitter they were. But, as it turned out, nontasters respond to all types of bitterness less intensely than tasters, and the degree to which people taste PROP can serve as a general indicator of their overall taste capacity. Judging from family studies, the inability to taste PROP is genetic and most likely due to a recessive gene. That would fit rather nicely with Bartoshuk's finding that there exists a subset of PROP-tasters supersensitive to bitterness. She calls them super-tasters.