Antennal movements were recorded 1 h before the beginning of the conditioning procedure and 1 h after the end of the conditioning phase. Before the recording period, each bee was left to acclimatize to the airflow for 20 sec. Each recording lasted 40 sec: 15 sec of airflow, 5 sec of olfactory stimulation, and 20 sec of airflow. Each bee was recorded four times, three recordings with an olfactory stimulation and one with a constant air flow. These recordings were separated by 1 min and were carried out in a randomized order. Three odorants were used; 1-hexanol (A) and 1-nonanol (B) were used as conditioned stimuli (CSs) and octanal (C) was used as a novel odor (NOd) (all from Sigma Aldrich). These odorants were chosen because they are easily learned and well discriminated by the bees (Guerrieri et al. 2005 (link)). In addition, these CSs have been used in several studies comparing SER and PER conditioning (Vergoz et al. 2007 (link); Carcaud et al. 2009 (link)). During these antenna movement recordings, proboscis extensions could be clearly seen and recorded by the experimenter. However, due to the position of the bee and the lighting directed only to the bees’ head, sting extensions could not be monitored during these recordings.