Task and Stimulus Processes May Explain Diverse/Inconsistent Working Memory Training Outcomes

Working Memory (WM) is a fundamental cognitive ability that encodes, manipulates, and maintains information for a brief amount of time. WM is involved in vital daily functions such as reasoning, problem-solving, and learning. Thus, there has been an increasing interest in enhancing WM by the use of “training” interventions. As such, many researchers have utilized various experimental paradigms in the form of varied tasks and stimuli to train WM. On one hand, the training results report benefits of WM training and transfer of these beneficial effects to domains similar to WM as well as different domains. On the other hand, some studies fail to observe beneficial effects. These inconsistent results have brought controversy, dividing researchers into believers and non-believers of WM training interventions. This is a general problem as many studies in the WM field assume a straightforward relationship between the construct of WM and its measurement through any of the variety of available WM measures, such as N-back. In this dissertation, we aim to further our understanding of WM by investigating WM through distinct but complementary lenses. In chapter 1, we focus on WM training studies that use N-back, a popular training task, to understand the efficacy of WM training interventions. In this chapter, we aim to point out that the features of training/assessment tasks and stimuli differ on many levels across different studies of WM, and that combining the results of these studies would be similar to mixing apples and oranges. In chapter 2, we bring mechanistic understanding by using brain signals as important mediators of behavior. Our goal is to not only understand the early and late brain mechanisms during various tasks and stimuli, but also to investigate other potential factors that can produce inconsistent results. After investigating the existing experimental paradigms and related brain signals, in chapter 3 we combine our knowledge of chapter 1 and chapter 2 by doing a multi-measure experiment. Our goal is to set the stage for studying the cortical arousal system, a key influencer of memory processes and learning through altering brain states. In conclusion, this dissertation furthers our understanding of WM, its training efficacy, and factors impacting it