Time-intensity ratings of nasal irritation from carbon dioxide.

In three experiments, subjects tracked intensity of nasal irritation during sustained presentation of carbon dioxide in the nose. Experiment 1 showed that: (i). functions of peak intensity vs. concentration and latency to first non-zero ratings agreed with published literature, thereby supporting the validity of the technique; (ii). on average, rated intensity peaked approximately 3-4 s after stimulus-onset and began to fall rapidly thereafter; (iii). large and stable individual differences in temporal dynamics occurred. Experiment 2 replicated experiment 1 with some methodological refinements. In experiment 3, application of the technique revealed that the nose regains sensitivity with very brief (300-500 ms) interruptions in presentation of carbon dioxide. In short: (i). the method developed here provides a temporally fine-grained tool to study the time-course of nasal irritation, and (ii). nasal irritation from carbon dioxide shows relatively rapid temporal dynamics.