The effect of adaptation on odor detection

The sensitivity of human Ss to a weak odor (hydrogen sulphide) following prior exposure to it varying in both duration (0–5 min) and concentration (4.05 × 10−7 to 24.40 × 10−7 mg/liter) was studied with a yes-no detection method and a specially designed olfactometer. The effect of adaptation was demonstrated, because the proportion of hits was lower the higher the concentration of the adaptation stimulus, when the response criterion, as measured by the proportion of false alarms, was fairly constant. By contrast, the proportion of hits was apparently independent of the duration of the exposure to the adaptation concentration. This finding suggests that the sense of smell is more stable than is usually believed. The paper ends with a discussion of the importance of considering adaptation in contemporary detection theory.