Delayed matching to sample is typically a two‐alternative forced‐choice procedure with two sample stimuli. In this task the effects of varying the probability of reinforcers for correct choices and the resulting receiver operating characteristic are symmetrical. Aversion of the task where a sample is present on some trials and absent on others is analogous to a yes/no recognition task. We describe data from two experiments where an asymmetry in performance in the yes/no task could be attributed to a change in response bias with increasing retention‐interval duration from a matching‐law perspective, but not from a signal‐detection perspective. Both approaches make explicit assumptions about response bias. The apparent inconsistency between the two approaches to the treatment of response bias is resolved in terms of a model proposed by K. G. White and J. T. Wixted (1999) which predicts asymmetrical matching‐law functions and receiver operating characteristics without making any assumptions about response bias.