“…The two test method to confirm conditioned inhibition (by both summation and retardation tests) has been widely adopted in animal studies, but has been harder to implement in human studies. In human studies, there have been some reports of conditioned inhibition confirmed by summation test ( He et al, 2013 ; Heym et al, 2014 ; Thurston and Cassaday, 2015 ) but these have been relatively few ( Sosa and dos Santos, 2019 ; Sosa and Ramίrez, 2019 ). Indeed, it has been argued that studies of feature negative inhibitory discrimination learning of the kind typically used to successfully demonstrate conditioned inhibition, but which do not include (or do not subsequently pass) the formal tests to confirm conditioned inhibition should also be considered ( Sosa and dos Santos, 2019 ; Sosa and Ramίrez, 2019 ).…”