The Notch receptor and its ligands constitute a ubiquitous signaling pathway found throughout all multicellular animal life. In addition to its highly conserved function in development, a growing body of evidence suggests Notch signaling has important roles to play in adult processes, including long-term memory (LTM) formation. Building on previous work showing a specific requirement for the Notch1 receptor in spatial memory in mice, I show here a similar requirement for the Notch ligand Jag1. Mice with mutations to Dll1 (another Notch ligand) and Lfng (a Notch regulatory protein) do not display such phenotypes. I propose a model in which signaling between Notch pathway components found in the adult mouse hippocampus (such as Notch1 and Jag1) is required for LTM encoding, with no requirement for pathway components not expressed in this tissue (such as Dll1 and Lfng).

This investigation explored implicit and explicit memory consequences of age differences in susceptibility to distraction when previous distraction occurs as target information in a later memory task. Younger and older adults were presented with either implicit (Study 1) or explicit (Studies 2 and 3) memory tasks that included previously distracting and new words. Study 1 explored whether prior exposure to distraction would transfer to improve memory when previously distracting words were included in list to be studied for a recall task. Older adults recalled more previously distracting than new words whereas younger adults recalled the same amount of previously distracting and new words. This initial study was implicit in its use of previously distracting information in that participants were neither informed nor aware of their prior exposure to words in the recall task. Here, only older adults’ memory was influenced by prior exposure to distraction and their recall actually increased to the level of younger adults with implicit use of distraction to improve performance. Subsequent studies investigated explicit influences of prior exposure to distraction on later memory. In Study 2, both younger and older adults showed reliable memory for previously distracting words in an explicit recognition task. These results suggest that although younger adults encode distraction, they do not transfer this information when previous distraction occurs as target stimuli in an implicit memory task. Study 3 investigated whether participants would transfer previous distraction to improve recall if the task was explicit in its use of previous distraction. When cueing instructions were given before the memory task informing participants of the connection between tasks, older adults once again recalled more previously distracting than new words. In contrast to the results of Study 1, younger adults also recalled more previously distracting than new words. Taken together, the results indicate that younger adults do encode distraction, but they require explicit instructions to transfer their knowledge of distraction to later tasks. In contrast, older adults apply their knowledge of distraction in both implicit and explicit memory tasks. Implications are discussed in terms of inhibitory control theory and age differences in strategies engaged in memory tasks.

The purpose of this thesis was to examine the contribution of episodic memory processes supported by the medial temporal lobes (MTL) to two goal-oriented non-episodic tasks, problem solving and semantic retrieval (verbal fluency). The reported experiments provide evidence for the hypothesis that MTL-based episodic processes are robustly involved in completing non-episodic tasks that are open-ended in that no algorithm or procedure can be applied to obtain task-relevant information. In Experiments 1 and 2, participants were administered the Means-End-Problem-Solving (MEPS) task, an open-ended test of social problem solving. People with impaired episodic memory associated with MTL damage or deterioration, patients with temporal lobe epilepsy or excisions (TLE) and older adults, performed worse than matched controls at solving such problems. Importantly, the participants’ performance on the MEPS as judged by the number of relevant solution steps generated correlated with the number of internal (episodically-relevant) but not external (semantically-relevant) details provided in the solutions. Thus, information derived from episodic memory benefited performance on the MEPS. Experiments 3 and 4 were conducted to ascertain whether open-endedness and episodic relevance are determinants of MTL contributions to performance on tests of verbal fluency, which traditionally are considered the domain of semantic memory. Using fMRI, Experiment 3 tracked the time course of MTL activation as participants performed a fluency task for categories that ranged in episodic relevance. The MTLs were more active throughout for categories that depended on autobiographical memories, not active for categories that were not episodically relevant, and active for episodic/spatial categories only later in the time course as the task moved from being well-defined to open-ended. The necessary involvement of the MTL in these tasks was confirmed by the pattern of spared and impaired performance of patients with TLE on category fluency tasks (Experiment 4). Together, these findings are consistent with the view that MTL-based processes are involved in tasks beyond those that test episodic memory. Furthermore, these studies suggest that performance on non-episodic tasks recruits the MTL most robustly when a task is open-ended.

In this thesis we consider estimation of the tail index for heavy tailed stochastic volatility models with long memory. We prove a central limit theorem for a Hill estimator. In particular, it is shown that neither the rate of convergence nor the asymptotic variance is affected by long memory. The theoretical findings are verified by simulation studies.

In the last two decades, many countries going through transitional justice have established truth commissions. Unlike conventional war tribunals, most truth commissions are established by the local government and local human rights groups. Truth commissions are still a nascent political choice, yet a sizable literature has developed around it, evaluating its potential as a new institution for dealing with the past and moving towards restorative justice. This work examines four major questions debated in the transitional justice literature over truth versus justice: 1) whether or not a truth commission is an valid alternative mechanism to seeking out retributive justice, 2) whether or not truth commissions are the product of political compromise which avoiding justice, 3) if truth commissions can be the agent of new national identity and national unity founded on the principles of universal human rights, and 4) if amnesty can be legitimized. This work aims to determine to what extent the idea itself of truth commissions has been actualized up to now and what lot it may expect in the future, despite incidental political restrictions and difficulties in the political transition. Despite the common assertion that the goals of truth commissions are to bring about official acknowledgment of the past, restore the dignity of the victims, and achieve reconciliation in divided society, this paper does not intend to evaluate the truth commissions in the past based on these criteria; nor does this work intend to argue what truth commissions can resolve in the transitional justice societies. Rather, this paper seeks to uncover what social reaction or human emotions truth commissions in the past have evoked in a divided society. To explore the question, this paper focuses on the distinctive activities and merits of truth commissions from the standpoint of retributive justice and looks into the important implication in the interaction between the victims and the perpetrators, as well as between the audience and those two parties. Roger Errera, a member of the French Conseil d’Etat, stated that “Memory is the ultimate form of justice.” Inspired by the statement, this work argues that justice can be found in the act of pursing truth, remembering it, and responding to those voices from the past.

Dual-process theories of reasoning (e.g., Gilbert, 1991; Stanovich & West, 1997) posit that decisions are mediated by two cognitive systems: a fast and automatic system which sometimes relies on past knowledge, and a conscious and effortful system which is more likely to adhere to the rules of logic. Dual-process accounts of memory (e.g., Joordens & Hockley, 2000) suggest that memory is influenced by two cognitive systems: a fast and automatic familiarity component, and a conscious and effortful recollection component. Both accounts suggest that cognition relies on two underlying systems, which are described similarly in the two literatures, suggesting some form of convergence in these two areas of research. Memory research may therefore be informed by considering decision making research, and vice versa. Combining these two theoretical perspectives, it follows that believable evidence should be less memorable than unbelievable evidence due to its shallow initial processing. Despite this fact however, when inferences are being made based on evidence retrieved from memory, believable evidence should actually have a larger impact than it does when it is provided online, whereas no change or a lesser impact should be noted for unbelievable evidence. Across 3 experiments these predictions are validated, suggesting that the impact of evidence on inferences depends not only on the believability of that evidence, but also on whether the decision is being made online or from memory. Specifically, memory-based inferences exaggerate the influence of believable but not unbelievable evidence, despite the fact that unbelievable evidence is more memorable.

The goal of this dissertation is to examine circumstances that encourage optimal encoding in memory. To accomplish this, several encoding manipulations were examined in the context of intentional forgetting. The typically robust item method directed forgetting effect is attributed to selective rehearsal: Participants intentionally select the Remember items as having priority in memory and rehearse them, at the same time choosing not to rehearse Forget items. A series of new experiments demonstrate that when encoding is already optimal, intentional selection processes are ineffective at improving memory further, thus eliminating directed forgetting. These circumstances must serve to promote differentiation of items in a distinctive context. Distinctiveness is defined as a relatively well-remembered set of items standing out against a weaker background set of items. Differentiation refers to individual items being processed in a unique manner such that they stand out against all other items. Only when items are differentiated and in a distinctive context will optimal encoding occur and directed forgetting be eliminated. Experiments 1-3 demonstrated that pictures, imagery, and production are all subject to intentional selection processes when studied alone (i.e., they produce directed forgetting). However, when these differentiated forms of encoding take place in the presence of weaker background items, encoding benefits from both differentiation and distinctiveness, and is optimal—resistant to intentional forgetting. Experiment 4 demonstrated that differentiation in a distinctive context is the key ingredient for eliminating directed forgetting: When encoding is improved with non-unique semantic processing, then item selection processes can still operate, and directed forgetting is produced. Taken together, these experiments show that when differentiated items are studied in a distinctive context, the strong items are not subject to directed forgetting. Yet when these same differentiated items are studied in a non-distinctive context, directed forgetting does occur. Differentiation in the absence of distinctiveness is not sufficient to eliminate directed forgetting, nor is distinctiveness in the absence of differentiation sufficient to eliminate directed forgetting. Both encoding processes must be in place for directed forgetting to be abolished. This pattern provides evidence that optimal encoding can be achieved when differentiation occurs in a distinctive context.

Dual-process theories of reasoning (e.g., Gilbert, 1991; Stanovich & West, 1997) posit that decisions are mediated by two cognitive systems: a fast and automatic system which sometimes relies on past knowledge, and a conscious and effortful system which is more likely to adhere to the rules of logic. Dual-process accounts of memory (e.g., Joordens & Hockley, 2000) suggest that memory is influenced by two cognitive systems: a fast and automatic familiarity component, and a conscious and effortful recollection component. Both accounts suggest that cognition relies on two underlying systems, which are described similarly in the two literatures, suggesting some form of convergence in these two areas of research. Memory research may therefore be informed by considering decision making research, and vice versa. Combining these two theoretical perspectives, it follows that believable evidence should be less memorable than unbelievable evidence due to its shallow initial processing. Despite this fact however, when inferences are being made based on evidence retrieved from memory, believable evidence should actually have a larger impact than it does when it is provided online, whereas no change or a lesser impact should be noted for unbelievable evidence. Across 3 experiments these predictions are validated, suggesting that the impact of evidence on inferences depends not only on the believability of that evidence, but also on whether the decision is being made online or from memory. Specifically, memory-based inferences exaggerate the influence of believable but not unbelievable evidence, despite the fact that unbelievable evidence is more memorable.

The goal of this dissertation is to examine circumstances that encourage optimal encoding in memory. To accomplish this, several encoding manipulations were examined in the context of intentional forgetting. The typically robust item method directed forgetting effect is attributed to selective rehearsal: Participants intentionally select the Remember items as having priority in memory and rehearse them, at the same time choosing not to rehearse Forget items. A series of new experiments demonstrate that when encoding is already optimal, intentional selection processes are ineffective at improving memory further, thus eliminating directed forgetting. These circumstances must serve to promote differentiation of items in a distinctive context. Distinctiveness is defined as a relatively well-remembered set of items standing out against a weaker background set of items. Differentiation refers to individual items being processed in a unique manner such that they stand out against all other items. Only when items are differentiated and in a distinctive context will optimal encoding occur and directed forgetting be eliminated. Experiments 1-3 demonstrated that pictures, imagery, and production are all subject to intentional selection processes when studied alone (i.e., they produce directed forgetting). However, when these differentiated forms of encoding take place in the presence of weaker background items, encoding benefits from both differentiation and distinctiveness, and is optimal—resistant to intentional forgetting. Experiment 4 demonstrated that differentiation in a distinctive context is the key ingredient for eliminating directed forgetting: When encoding is improved with non-unique semantic processing, then item selection processes can still operate, and directed forgetting is produced. Taken together, these experiments show that when differentiated items are studied in a distinctive context, the strong items are not subject to directed forgetting. Yet when these same differentiated items are studied in a non-distinctive context, directed forgetting does occur. Differentiation in the absence of distinctiveness is not sufficient to eliminate directed forgetting, nor is distinctiveness in the absence of differentiation sufficient to eliminate directed forgetting. Both encoding processes must be in place for directed forgetting to be abolished. This pattern provides evidence that optimal encoding can be achieved when differentiation occurs in a distinctive context.

In memory, encoding and retrieval are often conceived of as two separate processes. However, there is substantial evidence to suggest that this view is wrong—that they are instead highly interdependent processes. One recent example is from Jacoby, Shimizu, Daniels, and Rhodes (2005a), who showed that new words presented as foils among a list of old words that had been deeply encoded were themselves subsequently better recognized than were new words presented as foils among a list of old words that had been shallowly encoded. This paradigm, referred to as memory-for-foils, not only demonstrates a link between encoding and retrieval, but also has led to a proposal about what form this interaction is taking in this task. Jacoby et al. (2005a) proposed that people put in place a retrieval mode that leads to a reprocessing of the original encoding state, which is incidentally applied across both old and new items within the context of a recognition memory test. Such a constrained-retrieval account suggests an intimate relation between encoding and retrieval processes that allows for memories to be highly integrated. The goal of this thesis is to provide a better understanding of the generalizability and limitations of this memory-for-foils phenomenon and, ultimately, to provide more direct evidence for the interaction of these processes. Experiments 1 and 2 began by replicating the memory-for-foils phenomenon as well as an experiment by Marsh et al. (2009b) which confirmed that the phenomenon does not result simply from strength of encoding differences. Experiment 3 then substituted a deep vs shallow imagery manipulation for the levels-of-processing manipulation, demonstrating that the effect is robust and that it generalizes, also occurring with a different type of encoding. Experiment 4 extended the generalizability of the task to factual phrases. Experiment 5 then moved on to testing the encoding/retrieval interactions by once again employing the imagery encoding manipulation with an additional quality judgment in the final recognition memory test. Using the remember/know paradigm (Gardiner, 1988; Tulving, 1985) demonstrated that more highly-detailed memories were associated with foils from the test of deep items than with foils from the test of shallow items. From there, response time was used to infer processing speed in Experiment 6a, in a test of whether foils tested among deep items incur an advantage independent of the manipulation undergone by those items. When a lexical decision test replaced the final recognition test, there was no evidence of a memory advantage for “deep” foils over “shallow” foils. Finally, Experiment 6b provided compelling evidence for context-related encoding during tests of deeply encoded words, showing enhanced priming for foils presented among deeply encoded targets when participants made the same deep encoding judgments on those items as were made on the targets during study. Taken together, these findings provide support for the source-constrained retrieval hypothesis and for the idea of a retrieval mode. New information—information that we may not even be intending to remember— is influenced by how surrounding items are encoded and retrieved, as long as the surrounding items recruit a coherent mode of processing. This demonstrates a clear need to consider encoding and retrieval as highly interactive processes and to avoid conceptualizing them as entirely separate entities. This is a crucial part of increasing our understanding of the fundamental processes in memory.