Influence of training and experience on the perception of multicomponent odor mixtures.

Abstract

This study examined whether a previously established (D. G. Laing & G. W. Francis, 1989) limited capacity to discriminate and identify the components of olfactory mixtures resulted from the participants' lack of familiarity with the task, training designed to optimize cognitive and perceptual performance, or professional experience in odor discrimination. The participants were a trained panel of 10 women (23-43 years old), and an expert panel of 8 male professional perfumers and flavorists (25-55 years old). The individual chemical stimuli were 7 common dissimilar odorants of equal moderate intensity. An air dilution olfactometer delivered a single odorant or a mixture containing up to 5 odorants. The results indicated that for both panels only 3 or 4 components of a complex mixture could be discriminated and identified and that this capacity could not be increased by training. Therefore, the limit may be imposed physiologically or by processing constraints.

In search of the chemical basis for MHC odourtypes

“…Moreover, the olfactory system processes mixtures in complex ways. Human psychophysical studies indicate that mixtures of more than four or five odourants cannot be deconstructed into their components and that these mixtures are highly sensitive to relative potencies of the odourants in the mixture (Livermore & Laing 1996; see also Brennan & Kendrick 2006). Therefore, for complex mixtures, analysis of individual volatiles, based on what the instrumentation and methods find to be the most prominent, is likely to fail to identify the odours as detected by a mammalian olfactory system.…”

Synaptic Integration of Olfactory Information in Mouse Anterior Olfactory Nucleus

“…This finding suggests that initial stages of olfactory processing involve decomposition of a complex mixture into a combination of individual odor features (Wilson, 2000b;Haberly, 2001). However, humans have limited ability to discriminate individual components in odor mixtures (Livermore and Laing, 1996) and instead perceive complex mixtures as unitary olfactory objects. This quality of olfactory perception suggests that individual odorant features are integrated at higher levels of the olfactory system (Perez-Orive et al, 2002;Zou and Buck, 2006) (for review, see Wilson and Stevenson, 2003;Brunjes et al, 2005), although the nature of such integration remains enigmatic.…”

The fundamental role of memory in olfactory perception

“…Having first learned the labels for each of the odorants to be mixed, participants are presented with mixtures consisting of two or more constituents. Using a variety of different methods, participants can rarely identify an individual odor as being present when the mixture consists of three or more components [13]. Moreover, this identification ceiling is impervious to variations in the task [e.g.…”

“…cheese) or pure chemicals (e.g. skatole); or using different identification tasks) and is, crucially, the same in odor experts (perfumists and flavorists) as it is non-experts [13] (Fig. 1a).…”

“…2). If synthetic coding were due entirely to ligand -ligand interactions at the receptor and temporal synchrony of co-active mitral cells, it is unclear whether the simple discrimination of odorants from background odors or the analysis of simple, binary mixtures could occur -yet they do [13] (Fig. 1a).…”