Habituation is a response decrement resulting from repeated stimulus exposures. Sensitization results in an increase in responding following the presentation of a sensitizing stimulus. We sought to characterize the behavior of western harvester ants (Pogonomyrmex occidentalis) during uninterrupted exposure to a pure odorant stimulus. Animals were subjected to a 10-minute uninterrupted exposure to a pure odorant stimulus (10 µl of Heptanone) or an untreated cotton-tipped applicator (vehicle), followed by either the same or a novel stimulus (10 µl Heptanol) for 3-minutes (generalization test). Individual antennal retractions during stimulus exposure and generalization were hand-scored by a blind observer. There was a significant decrease in responding across both exposure conditions over time, suggesting that an untreated cotton-tipped applicator is sufficient to elicit retraction responses. Responding recovered between the end of habituation and start of the generalization test across all experimental conditions, suggesting that features of the protocol caused a sensitization of behavior.
