Acting on Behaviorally Relevant Events and the Impact this has on Attention & Memory

241 pagesWe attend to and, subsequently, remember some moments in time better than other ones. Understanding such interactions between attention and memory has been a longstanding topic in behavioral and brain sciences. One factor is the occurrence of behaviorally relevant events, which make attention fluctuate over time. These are events which require us to act on them in some fashion, to bring our ongoing behavior back in alignment with our task goals. Despite being more cognitively demanding than not acting, this somehow results in better memory for stimuli being encoded during that moment in time compared to stimuli encoded at other moments. Why is that? This dissertation investigates some of the cognitive, computational, and neural characteristics related to this phenomenon. In the first of four empirical articles covered herein, I replicate and extend previous findings on this phenomenon, demonstrating that the enhancement occurs not only for stimuli being intentionally encoded, but also for the incidentally encoded relational features between concurrent items. The second article utilizes diffusion decision modeling to reveal that the impact on memory is primarily on evidence accumulation. In the latter two empirical articles, I investigate what the neural origins of this phenomenon may be. Its underpinnings must involve a mechanism that is triggered by decision processes related to the appearance of behaviorally relevant events and thereby transiently facilitates processing in perceptual and memory regions. A promising candidate mechanism is the locus coeruleus neuromodulatory system. The third article investigates how, using functional magnetic resonance imaging, methodological decisions will affect characterization of this system's functional connectivity in the brain. In the fourth article, the locus coeruleus is contrasted to a different neuromodulatory system and shown to uniquely account for variance in activity in perceptual and memory areas, strengthening the idea that this system in particular may play an important role in this phenomenon. Combined, the studies presented in this dissertation reveal novel insights into the cognitive and computational characteristics of this phenomenon and argue that the locus coeruleus neuromodulatory system is a likely contributor to its manifestation