“…Food rewards following correct responses were administered only in pre-established trials (i.e., trial 4, 5, 7, 10, 13, 14, 16, and 19). In all testing trials (rewarded and unrewarded), the chicks kept searching for food because all items looked identical and this task was associated with food during training ( Rugani et al, 2011 , 2016b ; Rugani and Regolin, 2020 , 2021 ). This variable reward schedule has been designed to maintain motivation for food throughout the test, preventing response extinction over multiple unrewarded trials ( Rugani et al, 2016b ; Rugani and Regolin, 2020 ).…”