We will investigate the means by which subjects learn to recognize particular strings of events. In the version of the delayed sequence discrimination task we have developed, a series of three colored stimuli are presented, each for a specified duration separated from the next by a specified duration. Subjects are trained to respond when positive sequences are presented and to withold responses when other sequences are presented. In our initial exploration of this paradigm, we have found that birds quickly learn to discriminate a particular 4-sec long sequence of 3 colors from all other combinations of those colors. We will use variations in this paradigm to address the following: (1) What are the contents of and interactions between working and reference memory during sequence discrimination? (2) What sort of coding scheme is used by pigeons in discriminating sequences consisting of three or more stimuli? (3) How do the structural (e.g., sequence complexity) and physical (e.g., rate of presentation) properties of positive and negative sequences during training influence the acquisition and representation of sequences? Aside from bearing on these specific areas, our investigations will expand the paradigms available for the study of serially integrated behavior to include sequence recognition.