Reading first or smelling first? Effects of presentation order on odor identification.

Verbal labels are potent manipulators for olfactory perception, and verbal descriptors used in a cued olfactory identification test will influence the testing results. The main aim of the present study was to test whether the order of presentation of the odorants and the corresponding set of labels (verbal descriptors with or without pictures) would influence the results of a psychophysical odor identification test in 100 normosmic subjects (49 women and 51 men) and 100 patients with olfactory dysfunction (61 women and 39 men). Additionally, we investigated whether the scores would be different between subjects identifying odors from a list of verbal descriptors and subjects using both pictures and verbal descriptors. The subjects were examined with the extended, 32-item "Sniffin' Sticks" identification test. We found that the scores of normosmic subjects were significantly higher when the subjects were presented with label options prior to smelling, whereas for patients the scores in the two conditions did not differ. Moreover, in both groups the scores were not significantly different when the subjects were presented either with verbal descriptors only or with verbal descriptors and pictures. Our findings seem to be of importance not only to research involving psychophysical olfactory identification tests or in a clinical context, but also to further experiments investigating human olfaction and cognition.