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© Cyril FRESILLON/CRCA/CNRS Images
Proboscis extension reflex (PER) appetite conditioning device for bees. When their antennae come into contact with a sugary solution, bees extend their proboscis (mouthparts specialising in suction). Research scientists initially present a neutral odour together with the sugary solution, causing the bee to form an association between the odour and the sugary reward. Here, the experimenter is rewarding the bee by presenting it with a toothpick soaked in sugar solution. Once this has been learned, the bee extends its proboscis on detecting the neutral odour alone, showing that the association has been made. The experiment is filmed so that the bee’s reaction can be observed and analysed in detail.