Learning Influences the Perception of Odor Mixtures

Abstract

In this study, we investigated the influence of semantic and perceptual learning on the perception of odor blending mixtures, i.e., mixtures eliciting a different odor quality as compared with their components. Following a between-groups design, we set out to examine whether being pre-exposed to target mixture odor labels (semantic learning) and to the mixture's odor components (perceptual olfactory learning) would modify the perception of odor mixtures quality. In a first experimental condition, a group (control) of 28 subjects evaluated the odor quality of mixtures and then their components. In this condition, subjects were not exposed to the individual odor components (no perceptual learning) and were only weakly exposed to the target mixture odor labels (weak semantic learning) when asked to evaluate the quality of the mixtures. In a second experimental condition, a group (learning) of 29 other subjects performed the same tasks but evaluated first the components and then the mixtures. In this condition, subjects have experienced both perceptual and strong semantic learning when asked to evaluate the quality of the mixtures. Within each condition, odor quality was evaluated following two verbal tasks: a free description task and a choice between several odor attributes. The comparison of the data obtained in both experimental conditions revealed that semantic and perceptual learning could influence odor mixture quality and suggested a differential influence of both learning types according to mixture complexity.

Experience influences elemental and configural perception of certain binary odour mixtures in newborn rabbits

“…The results from the present study show that experience of a mixture or its components may rapidly affect the mode of perception in newborn rabbits, as previously shown in human adults (Stevenson, 2001;Le Berre et al, 2008;Le Berre et al, 2010). At least for certain mixtures, processing might operate on a continuum from strictly elemental to strictly configural perception: the initial perception of a mixture (free of any experience) would be located somewhere in between, depending on the mixture, whereas experience with either the mixture or the components would shift the perception to one or another mode.…”

“…The AB mixture included 0.3ϫ10 -5 and 0.7ϫ10 -5 gml -1 of components A and B, respectively; this 30/70 v/v ratio elicits the perception of a pineapple odour in human adults because of blending properties (ThomasDanguin et al, 2007;Le Berre et al, 2008;Le Berre et al, 2010;Barkat et al, 2011), and weak configural perception in newborn rabbits Coureaud et al, 2009;Coureaud et al, 2011). The AC mixture contained a 50/50 ratio of each component (0.5ϫ10 , a ratio chosen on the basis of a preliminary assay in humans).…”

“…In human adults, an AB mixture composed of ethyl isobutyrate (A) and ethyl maltol (B), smelling like strawberry and caramel, respectively, induces the configural perception of 'pineapple' (Le Barkat et al, 2011). Such a mixture has been called a blending mixture (Dreumont-Boudreau et al, 2006;Le Berre et al, 2008;Le Berre et al, 2010;Barkat et al, 2011). Recently, configural perception of the same AB mixture has also been reported in newborn rabbits: after a single conditioning to AB, pups respond to odorants A and B, showing abilities to extract the odour of each element during conditioning.…”

“…In adult humans or animals, experience with components improves the elemental perception of mixtures including them. For instance, pre-exposure to each odorant of the weak configural AB mixture (cited above) during two 30min sessions favoured the elemental perception of this mixture Le Berre et al, 2010). Configural processing of an odour mixture is also improved after repeated exposure to it (Livermore et al, 1997;Stevenson, 2001).…”

“…Gottlieb, 1983). Following a more or less intensive protocol, we exposed rabbit pups to the AB mixture cited above, initially perceived in a weak configural mode Coureaud et al, 2009;Coureaud et al, 2011;Le Berre et al, 2008;Le Berre et al, 2010;Barkat et al, 2011), or to one of its components, before testing their responsiveness to the mixture and to the single odorants. We hypothesized that variations in experience may modulate the perception of AB by neonates (Expt 1).…”