Pleasantness of olfactory and trigeminal stimulants in different Italian regions

Although individuals categorize odors according to their pleasantness, experience may also influence odor perception-a phenomenon that partially explains why different populations perceive odors differently. Italy, which comprises 20 regions, is characterized by very different cultures. In the present study, we investigated for the first time how Italian regional differences can affect odor perception. 254 healthy volunteers coming from northern, central, southern Italy, and Sicily, one of the two major Italian islands, were recruited in Padua, Rome, Naples, and Syracuse, respectively. Olfactory function was tested with Sniffin' Sticks identification subtest. Subjects who had a score in the range within the mean identification value ± 1 SD, in accordance with the age classes identified in the literature, were asked to judge the odor pleasantness of 20 substances. The hedonic tone of the odorants was categorized as pleasant, neutral, unpleasant, and very unpleasant. Some odorants were appreciated more in northern Italy than in the other parts of the country, whereas others were appreciated more in the south and in Sicily than in the north. Unpleasant odorants were judged less unpleasant in central Italy. Some odorants such as strawberry and vanilla were perceived similarly in all the regional areas. Our study indicates that in Italy, hedonic perception of odorants differs probably in relation with genetic, cultural, and environmental factors. Further investigation is needed to delve deeper into the factors that influence the quality odor perception amongst humans.