One day after conditioning, extinction training was conducted as described previously.28 Testing was conducted in a novel context (‘context B’) (cylinders with black/white-chequered walls and a solid Plexiglas opaque floor cleaned with a 1% acetic acid/99% water solution) housed in a different room from conditioning. After a 180s acclimation period, there were 50 × CS presentations (5-s inter-CS interval).