Katherine Dyer

Scientists have been interested in the mechanisms which allow organisms to perform complex behaviors, such as behavioral sequences, for decades. One such type of complex sequential behavior which is of interest to scientists is serial pattern learning. Serial pattern learning, the performance of patterned sequences of responses, has been investigated in many species including rats and humans (Fountain & Rowan, 1995b). Both past and current research of this phenomenon seeks to better understand the mechanisms underlying this form of complex behavior. For example, rats can recruit multiple cognitive mechanisms during serial pattern learning (Muller & Fountain, 2010, 2016; Stempowski, Carman, & Fountain, 1999). Furthermore, prior researchers attributed differences in the learning and performance of serial patterns to these different cognitive mechanisms (Muller & Fountain, 2010, 2016). However, simpler explanations of these findings, such as differences in learning experience, remained unexplored in the research. Thus, the current study investigated the influence of these simpler mechanisms on serial pattern learning processes. To determine how amount of learning experience affects pattern performance, rats were trained on one of two patterns of varying structures. One pattern equated amount of learning experience amongst element types in the pattern, while another pattern contained unequal amounts of learning experience amongst element types in the pattern. Effects of amount of learning experience were measured during acquisition, on pattern performance during a muscarinic cholinergic drug challenge, and on pattern performance during a retention test. Results showed that the amount of learning experience rats had with element types per pattern completion affected the rate at which those various pattern element types were learned. However, amount of learning experience did not affect subsequent learned-pattern performance in later challenges. In a second experiment, the effects of serial pattern mastery on pattern performance during drug challenges were examined. One group of rats received three drug challenges to challenge three separate pattern element types at the same levels of mastery. Another group of rats received one drug challenge at the end of acquisition to challenge three separate pattern element types at different levels of mastery. Results showed that the level of mastery at which pattern elements were challenged did not affect pattern performance during drug challenges. Therefore, though differences in pattern learning are not wholly due to the separate cognitive mechanisms recruited during serial pattern learning, as previously theorized, findings continue to support that differences in learned-pattern performance are likely a result of these separate cognitive mechanisms. Thus, the serial pattern learning process involves both simple and complex mechanisms which contribute to how sequences of behaviors are learned and performed by animals.