Further developments in the measurement of working memory in rodents.

This article reviews automated test procedures that can be used to study memory for discrete/trial-unique events in rodents and other animals. A distinction is made between delayed response tasks, i.e. those tasks for which all information necessary to determine the correct response is available prior to the retention interval, and delayed comparison tasks, i.e. tasks in which the subject must compare stimuli presented prior to and after the retention interval in order to determine the correct response. Delayed comparison procedures potentially provide a purer estimate of the subject's memory capacities, but have also been more difficult for rodents to acquire. Suggestions are offered for potential directions for improved delayed comparison tasks.