Startle reflex modulation by pleasant and unpleasant odors in a between-subjects design.

Participants were presented with an acoustic startle probe while they smelled either a pleasant odor or an unpleasant odor (n = 40 per condition). Within each condition, participants were presented with four blocks in which odor was present and four in which odor was not present (no-odor control). Significant differences were found in both conditions between the odor and no-odor blocks. In the unpleasant odor condition, blink magnitude was greater during the odor blocks; in the pleasant odor condition, blink magnitude was smaller during the odor blocks.