What economic factors prevent democratic breakdowns? Since the beginning of the 20th century, more than a hundred countries in the world have transformed their political regime types into democracies. However, not every transition to democracy continued without interruption. Even though some democracies continued without any breaks, some others relapsed into authoritarian regimes via military coups. The consensus in the literature is that wealthy countries are less likely to experience democratic breakdowns. I argue that wealth alone is not enough to increase the duration of democracies. Using quantitative cross-national survival analysis, I show that temporal and international context change the impact of wealth on democratic survival. In addition, I investigate whether democratic survival is more likely in countries where national income is evenly distributed.

<p> Numerous studies have shown retrieval practice to be an effective strategy for improving memory. One account proposed to explain this benefit is the episodic context account (Karpicke et al., 2014). This account proposes that contextual information is reinstated and updated when an item is retrieved. This updated context is then used to aid in retrieval. Examining memory for contextual information, in addition to item memory, may provide additional insight into retrieval practice and what contextual cues are relevant in retrieval. The current study examined memory for temporal-contextual information at 2 different grain sizes: (a) memory for which list a word occurred in, and (b) memory for when an item occurred within a list. Previous research has shown that retrieval practice enhances memory for list temporal contextual information, as assessed by a list discrimination task (Brewer et al., 2010; Chan & McDermott, 2007). In contrast, Karpicke and Zaromb (2010) found worse memory following retrieval practice (relative to restudy) for within-list temporal-contextual information, as assessed by an order reconstruction task. In both experiments of the current study, participants studied multiple lists of words and either engaged in a word stem completion cued recall task, or restudied the words. Our results were partially consistent with previous research. We found no difference in performance between the retrieval practice and restudy groups when assessed on a list discrimination test. However, performance was worse for the retrieval practice group relative to restudy when assessed on an order reconstruction task. Finally, in both experiments, there was no difference in recognition accuracy. Overall, our results suggest that certain retrieval practice tasks may differentially affect memory for various grain sizes of temporal-contextual information. </p>

Temporal context memory is a type of episodic memory that refers to memory for the timing of events. Temporal context includes environmental cues that provide information about the time point at which an event happened. The purpose of the present studies is to investigate the brain mechanisms underlying temporal context processing by using both fMRI and ERP techniques. The fMRI study investigated whether hippocampal representations in CA1 and DG/CA3 subfields were sensitive to the flow of physical time, and if so, whether the number of events that occur during a time period influences the temporal representation of a target event. Results showed that both CA1 and DG/CA3 were sensitive to the flow of physical time, which was indicated by higher representational similarity between two pictures that occurred closer in time than those that occurred more distant in time. However, the variety of preceding events did not influence temporal representation, which was demonstrated by the lack of a significant representational similarity difference between two pictures that were interleaved with variable events as opposed to similar events. The ERP study compared the ERP correlates of temporal to spatial context. Results showed that temporal and spatial contexts had overlapping ERP effects except that the ERP effects of temporal context were more frontally distributed than spatial context. Both the fMRI and ERP studies indicate that temporal context is associated with similar neural correlates to other types of context in episodic memory. / Ph. D. / Episodic memory is memory for where and when an event happened. The ability to memorize the timing of events relies on one type of episodic memory: temporal context memory. Temporal context includes environmental cues that provide information about the time point at which an event happened. The purpose of the present studies was to investigate the brain mechanisms underlying temporal context processing by using both functional magnetic resonance imaging (fMRI) and event and event-related potential (ERP) techniques. The fMRI study focused on hippocampus, one of the key brain regions process non-temporal contexts (i.e. spatial context, which refers to where an event happened), and investigated which subfields (CA1 and DG/CA3) in the hippocampus were sensitive to the flow of physical time. And the second purpose of the fMRI study was to examine whether the variety of events that occur during a time period influences the temporal representation. Results showed that both CA1 and DG/CA3 were sensitive to the flow of physical time. However, the variety of events did not influence temporal representation. Since CA1 and DG/CA3 are also critical for non-temporal context processing, these results indicate that temporal context has same neural mechanisms as non-temporal contexts. The ERP study investigated the brain activity as a whole and directly compared the ERP correlates of temporal to non-temporal context. Results showed that temporal and nontemporal contexts had overlapping ERP correlates except that the ERP effects of temporal context were more frontally brain region distributed than spatial context. Therefore, both the fMRI and ERP studies indicate that temporal context is associated with similar neural correlates to other types of context in episodic memory.

Temporal context memory is memory for the timing of events. People can make temporal judgments based on strategies such as assessing the relative familiarity of events or inferring temporal order from the semantic associations among events. The purpose of present study is to investigate the brain regions that support temporal context retrieval in the absence of such non-temporal strategies (i.e. pure temporal context memory). We used three word familiar phrases (triplets) as stimuli. In study phase, three words were presented quickly one after another in either familiar or scrambled order. Participants were instructed to read aloud each word and try to remember the order of the words. Then they were tested on their memory for the order of the words in each triplet. We propose that memory for the scrambled triplets reflects primarily temporal retrieval for two reasons. First, participants were prevented from using semantic strategies during encoding. Second, the relative familiarity of the words in each triplet was similar and not diagnostic of the order of the words during encoding. Neuroimaging results indicate that temporal context retrieval, memory for the order of words in scrambled triplets, was associated with the hippocampus, parahippocampal cortex, ventromedial prefrontal cortex, retrosplenial cortex, and posterior cingulate, which are consistent with the retrieval of non-temporal context in episodic memory. The results also suggest that temporal context retrieval could rely on familiarity, which was demonstrated by the higher accuracy and greater activation of PRc in familiar phrases and scrambled triplets presented in studied order in the test phase. / Master of Science

Evidence suggests that when memories are reactivated they become labile and can be updated or even erased. Reactivation induces plasticity in memory representations, rendering them fragile, much as they were after initial acquisition. When a memory has been reactivated it must be re-stabilized, which requires reconsolidation. A recent set of studies established the phenomenon of memory reconsolidation for episodic memory (Hupbach et al., 2007, 2008, 2011). That reconsolidation effects apply to explicit memory, which requires conscious recollection, has far reaching implications. In the Hupbach et al. studies the ability of subtle reminders to trigger reconsolidation was investigated; these reminders consisted of the same spatial context, the same experimenter and a reminder question. Given we live in a predictable world, episodes are not random occurrences of events in time and space, but instead consist of statistical and semantic regularities. This leaves open the question of whether semantic relations and statistical regularities between episodes can trigger a reactivation of episodic memory. If so, how would this affect the status of the reactivated memory? This dissertation explored the role of semantic relatedness between the elements of different episodes in memory reactivation and subsequent updating. We focused particularly on categorical and contextual aspects of semantic relations. A series of experiments considered different kinds of semantic relations between elements of episodes, providing evidence of memory reactivation and updating as a consequence of basic level category relations between items in two separate episodes. We also tested the predictions of the Temporal Context Model (TCM) (Sederberg et al., 2011) for our experimental paradigm and show that the current TCM model is not able to account for all the effects of semantic relatedness in the reconsolidation paradigm. Finally, we explore an alternative approach that seeks to explain memory reconsolidation as Bayesian Inference. Our results provide support for this Bayesian framework, showing the potential of it for exploring different aspects of memory organization.

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