Available in MAP and MARS

Olfactory sensitivity is the lowest concentration at which the presence of an odor can be reliably detected. The variable is measured with the odor threshold test from the OLFACT Test Battery (Osmic Enterprises Inc., Cincinnati, OH) and a portable olfactory test instrument. See the subcategory description for the OLFACT device measures for detailed information. The measurement employs a single staircase with reversal paradigm.

The participant is presented two puffs of air, one after the next, and asked to identify which contains the odor. After a response is recorded, the next set of stimuli is presented. Stimuli are presented in ascending concentration until the participant correctly identifies the odorant containing the stimulus. A starting point is determined once the participant identifies the correct stimulus twice in a row. After the starting point is identified, a 1-step lower concentration is presented. A miss (incorrect identification) triggers a reversal of the staircase (i.e., a 1-dilution step higher concentration is presented next). If this concentration is missed again, the next higher concentration is administered until a dilution step is correctly identified twice in a row. Then a lower concentration is presented. Testing is completed when three reversals of the staircase have been found.

This variable is the mean of the concentrations of the last two reversals of the staircase.

Note: If four misses occur at step 1, or four consecutive hits occur at step 13, the test is terminated.