Appetitive conditioning 2 CS-US interval Chasmagnathus 2 Chasmagnathus granulata 2 Chasmagnathus granulatus 2 Crab 2 Decapoda (Crustacea) 2 Habituation 2 Trace conditioning 2 adaptation 2 animal experiment 2 appetite 2 article 2 brain region 2 controlled study 2 crab 2 environment 2 habituation 2 instrumental conditioning 2 learning 2 male 2 nonhuman 2 reinforcement 2 state dependent learning 2 stimulus 2 stimulus response 2 time 2 weight 2