Phonological and perceptual components of short-term memory for odors

Just as a written word can be encoded and retained in memory either verbally or in a visual form, so it might seem that an odor might be retained as either a verbal description/name or as a perceptual (olfactory) code. However, one view has it that olfactory memory in the short term does not exist as a separate perceptual code. This was examined in an experimental paradigm in which errors in memory could be recognized as deriving from the substitution of similar verbal codes or of similar olfactory codes. The set of odorants presented for recall was divided into three groups: (i) base odorants (odorants that might be replaced in memory either by similar verbal or similar olfactory representations); (ii) verbal foils (stimuli dissimilar to the base stimuli in odor but which is similar in name); and (iii) odor foils (the reverse). The substitution errors made when attempting to recall test odorants were classified as verbal errors or olfactory errors. A substantial proportion of the errors were olfactory, but verbal errors also occurred. These results support the presence of short-term perceptual olfactory memory, rather than simply verbal encoding of olfactory perceptions.