Phenomenological differences between familiar and unfamiliar odours

Unfamiliar odours are harder to discriminate than familiar odours. We explored the phenomenal basis of this difference. In experiments 1a and 1b, participants profiled odour quality for two sets of familiar and unfamiliar odours. In both cases unfamiliar odours were redolent of more odour qualities than familiar stimuli. In experiment 2, participants received (i) a set of familiar and unfamiliar odours and learnt their names, and (ii) a further set of familiar and unfamiliar odours to which they were exposed. Participants then profiled these stimuli as well as a further unexposed set of familiar and unfamiliar odours. Exposure, but not naming, led to a significantly smaller difference between the familiar and unfamiliar stimuli, in terms of their redolence to other odours, when compared to unexposed control stimuli. Unfamiliar exposed odours were also judged as less redolent than unexposed unfamiliar odours. These observations are consistent with a mnemonic basis for odour-quality perception.