Familiarity enhances the effectiveness of odors as cues in paired-associate memory

Previous olfactory paired-associate (PA) studies showed that odors are less effective associative cues than other sensory modalities. It has been suggested that odor familiarity might improve memory stability, thereby facilitating PA memory performance. In the current study, we designed three experiments to investigate whether enhanced odor familiarity would also enhance the effectiveness of odors in a PA memory paradigm. In Experiments 1 and 2, subjects associated target shapes with eight familiar and eight unfamiliar odors (based on normative odor ratings in Experiment 1 and individual ratings in Experiment 2). The results of both experiments indicated that familiar odor cues were more effective in the retrieval of targets than unfamiliar odor cues. In Experiment 3, we investigated whether becoming (more) familiar with odors would also enhance the effectiveness of odors as cues in an olfactory PA test. An experimental group was familiarized with half of the pre-rated odors (16 odors, eight high and eight low familiar) over 4 weeks prior to the laboratory procedure while a control group was not. Both groups engaged in a PA memory paradigm in which they associated 32 odors (16 high and 16 low familiar odors) with black and white complex shapes. The results indicated that odor training led to enhanced PA learning for low-familiar odors in relation to untrained low-familiar odors. These results provide further evidence for odor familiarity as one of the critical features in olfactory processing and memory.