Olfactory working memory: effects of verbalization on the 2-back task.

Working memory for odors, which has received almost no attention in the literature, was investigated in two experiments. We show that performance in a 2-back task with odor stimuli is well above chance. This is true not only for highly familiar odors, as has been shown by Dade, Zatorre, Evans, and Jones-Gotman, NeuroImage, 14, 650-660, (2001), but also for unfamiliar ones that are notoriously difficult to name. We can conclude that information about an olfactory stimulus can be retained in the short term and can continuously be updated for comparison with new olfactory probes along the lines of a functional odor working memory. However, the performance in the working memory task is highly dependent on participants' verbalization of the odor. In addition, results indicated that odor working memory performance is dependent on the ability to discriminate among the odor stimuli (Experiment 2). The results are discussed in relation to recent ideas of a separate olfactory working memory slave system.