In behavioural terms, to remember a stimulus is to respond to that stimulus at a later time. Remembering can thus be seen as discriminative behaviour along the stimulus dimension of time. This implies that phenomena such as stimulus generalisation, which have been shown to occur in discrimination learning along many other stimulus dimensions, may occur also in discrimination along the stimulus dimension of time, i.e. in remembering. Data from operant studies with pigeons and hens have supported this. This book reports a highly novel finding, namely the first evidence for the occurrence of peak shift in a remembering process. When hens were poorly rewarded for correct remembering after a short delay, but richly rewarded for correct remembering after a longer delay, they remembered best after an even longer delay. This phenomenon was not predicted by any traditional theory of memory, and cannot be explained by the century-old standard construct of memory trace decay. This work will interest a wide range of researchers in psychology, cognitive neuroscience, biology, or anyone interested in challenging their thinking with a radically different view of the nature of memory.