Potentiation of delayed matching with variable delays

In a delayed matching-to-sample procedure, pigeons chose a comparison stimulus that matched a sample stimulus presented earlier in the trial. The duration of the delay between sample-stimulus presentation and comparison-stimulus presentation was either varied over five values within each session or held constant within each session but varied over five blocks of sessions. Accuracy of matching to sample was higher overall with variable delays than with delays fixed within sessions. The result indicates that remembering depends on the temporal context provided by delay intervals.