Odor Identification: Perceptual and Semantic Dimensions

Abstract

Five studies explored identification of odors as an aspect of semantic memory. All dealt in one way or another with the accessibility of acquired olfactory information. The first study examined stability and showed that, consistent with personal reports, people can fail to identify an odor one day yet succeed another. Failure turned more commonly to success than vice versa, and once success occurred it tended to recur. Confidence ratings implied that subjects generally knew the quality of their answers. Even incorrect names, though, often carried considerable information which sometimes reflected a semantic and sometimes a perceptual source of errors. The second study showed that profiling odors via the American Society of Testing and Materials list of attributes, an exercise in depth of processing, effected no increment in the identifiability/accessibility beyond an unelaborated second attempt at retrieval. The third study showed that subjects had only a weak ability to predict the relative recognizability of odors they had failed to identify. Whereas the strength of the feeling that they would 'know' an answer if offered choices did not associate significantly with performance for odors, it did for trivia questions. The fourth study demonstrated an association between ability to discriminate among one set of odors and to identify another, but this emerged only after subjects had received feedback about identity, which essentially changed the task to one of recognition and effectively stabilized access. The fifth study illustrated that feedback improves performance dramatically only for odors involved with it, but that mere retrieval leads to some improvement. The studies suggest a research agenda that could include supplemental use of confidence judgments both retrospectively and prospectively in the same subjects to indicate the amount of accessible semantic information; use of second and third guesses to examine subjects' simultaneously held hypotheses about identity; use of category cuing or similar techniques to discover the minimum semantic information needed to precipitate identification; some use of subjects trained in quantitative descriptive analysis to explore whether such training enhances semantic memory; and judicious use of mixtures to explore perceptual versus semantic errors of identification.

Symmetry, Stereotypy, and Topography of Odorant Representations in Mouse Olfactory Bulbs

“…These findings are consistent with human psychophysical studies demonstrating that on average the individual components in mixtures of up to four odorants can be discriminated (Livermore and Laing, 1996;Cain et al, 1998;Livermore and Laing, 1998). However, human studies also reveal that individual components are perceived as less intense when presented in mixtures, which correlates with behavioral paradigms such as overshadowing (Rescorla, 1980;Linster and Smith, 1997).…”

Implicit and explicit memory for odors: Hemispheric differences

“…This response mode seemed to require less lexical processing than if the name was required. However, it was pointed out that a "feeling of knowing" did not qualify, because it is a state of mind that does not reliably predict performance on a cued odor identif ication test (Cain et al, 1998). By the instructions, the participants had to feel confident of having identified the odor.…”

“…Studies of odor memory have dealt principally with explicit forms of memory even though implicit forms may provide a common means to learn about odors (Cain, de Wijk, Luleijan, Schiet, & See, 1998;de Wijk, Schab, & Cain, 1995;Herz & Engen, 1996). In everyday life, odors often lie in a contextualrelationship to other events, such as a rain shower, spring thaw, dinner under way, or soiling of a diaper.…”

Difficulty in evoking odor images: The role of odor naming

“…However, this possibility appears to be problematic, in that it is not consistent with the finding that teaching participants to name an odor improves performance. The position we take here is best summed up by Cain, de Wijk, Lulejian, Schiet, & See (1998): "Unstable access to semantic information presumably largely governs performance at identification" (p. 320).…”