Effects of training on odor judges scoring intensity

Objective: This pilot study was intended to test whether a training protocol improved validity of odor judges (OJs), with or without experience, and whether odorant types differed in error proneness. Methods: The OJs (four experienced, two inexperienced) completed a 4-phase training protocol based on the American Society of Testing and Materials standards (ASTM): (i) introduction to sensory scales, n-butanol reference, sniffing techniques; (ii) pretraining measurements; 20 samples of varying intensities of four unpleasant and three pleasant odorants; (iii) exercises assessing quality, intensity, ranking, and matching; and (iv) post-training measurements. Main outcome measures: Subjects' intensity scores were analyzed as the absolute difference from the 'true' intensity (ASTM n-butanol standard) using repeated measures ANOVA. Results: Training significantly (P = 0.02) reduced OJ errors. Experienced and novice judges did not differ in average errors (P = 0.99), or in improvement in error from pre- to post-training (P = 0.94). Improvement was consistent from pre- to post-training for all odorants except dimethylsulfide for which errors worsened (P = 0.01). Unpleasant and pleasant odorants differed (P = 0.006) in error. After removing water the effects of water control scores from the pleasant odorants, the difference was not significant (P = 0.26). Conclusions: The OJs improved in their ability to assess odor intensity irrespective of previous experience. Training is recommended for all OJs prior to research trials.