Olfactory Acuity and Automatic Associations to Odor Words Modulate Adverse Effects of Ammonia

Abstract

Introduction: Adverse effects of malodorous chemicals in humans are usually described as negative emotional reactions and impaired cognitive performance. Sensory acuity and automatic associations to odor words could influence cognitive processing of chemosensory stimulation and such adverse effects. We hypothesized that adverse effects are amplified in individuals with lower olfactory acuity due to a more automatic and emotional odor evaluation process. In contrast, adverse effects should be attenuated if odor words such as smell automatically activate positive mental associations. Methods: After the assessment of olfactory acuity and automatically activated associations in standardized tests, 37 women were exposed to ascending concentration steps of ammonia (0–10 ppm) in an exposure laboratory for 75 min. Participants rated hedonic valence, intensity, and pungency of ammonia and performed working memory and response inhibition tasks. Results: Olfactory acuity modulated ratings of hedonic valence and working memory performance: Participants with lower olfactory acuity reported stronger odor unpleasantness and showed impaired performance compared to participants with higher olfactory acuity during the exposure to 10 ppm ammonia. In the lower olfactory acuity group, participants with strong automatic associations between odor words and positive valence rated ammonia at high concentrations to be less pungent than participants with weaker automatic associations. Conclusions: We conclude that sensory acuity and automatically activated associations modulate chemosensory-mediated adverse effects of ammonia. Beyond established self-report measures, these individual characteristics could help explain differences in environmental odor annoyance.