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The primary objective of the present thesis was to investigate factors that influence the creation of false memories using the Deese-Roediger-McDermott (DRM) paradigm. The experimental research addressed the effect of age, list length, and list content on the magnitude of the DRM illusion with a view to testing assumptions derived from activation-monitoring theory and Fuzzy Trace Theory. In the first experiment, I wanted to determine whether the DRM paradigm is appropriate for use with New Zealand English-speaking adults. In addition, Experiment 1 was designed to assess the effect of prior recall on recognition performance. To answer these questions, I assigned half of the participants to a recall-plus-recognition condition and the remaining participants to a recognition-only condition. Rates of false recall and recognition were comparable to those reported in the literature, which suggested that the task is suitable for use with New Zealand adults. Furthermore, prior recall enhanced correct recognition but it did not affect false recognition. In Experiment 2, I examined how manipulations of list-length affected children and adults' susceptibility to the DRM illusion. Ten-year-olds and adults studied eight lists of either 7 or 14 words. In the 14-word condition, adults falsely recalled more critical targets than children; however, in the 7-word condition, there was no age difference in false recall. In addition, adults falsely recognised a greater proportion of critical targets than children, however, this effect was not dependent on the length of the study list. In Experiments 3A and 3B, I examined whether presenting highly familiar study materials would enhance children's susceptibility to false memories. Ten-year-old children and adults studied four standard DRM lists, four new lists that centred on 'child-friendly' concepts, such as birthday and school (CF lists), and four lists derived from child word-association norms. In both experiments, there was no age difference in rates of false recall. In addition, presenting material that was deemed more developmentally appropriate did not enhance children's susceptibility to false memories relative to adults. In Experiment 4, I introduced a post-recall phase to examine why the DRM illusion is less likely to occur when short lists are presented and when the materials are child-friendly. During the post-recall phase, participants were asked to report any other words that they had thought of during the presentation or recall of the study lists. Thinking about the target word, but remembering that it had not been presented, could not account for decreased levels of false recall in the short-list condition. Similarly, with the CF lists, it appeared that the list items were less likely to activate the critical target for both children and adults. In the final three experiments, I explored the assumptions outlined in activation-monitoring theory and fuzzy-trace theory to determine which model provided the best account of the findings obtained to date. To explore the activation-monitoring account, children and adults completed word association tasks. To explore fuzzy-trace theory, children and adults were given a gist extraction task where they had to identify the critical targets associated with each list. Collectively, the results of the present thesis fit more comfortably within an activation-monitoring framework than they do within the fuzzy-trace framework. Although the precise mechanisms underlying the DRM illusion have yet to be elucidated, the present findings suggest that gist extraction, activation processes, and source monitoring each play a substantial role in mediating false memory levels.

The current study introduced a new measure for the study of naturalistic memory, which involved the use of a homogeneous, controlled event for all participants. We tested participants’ memory for this so-called staged event with both the Autobiographical Interview (AI) and our novel receiver operating characteristic (ROC) task. Statistical analyses indicated that scores on the AI and on our new ROC measure showed time sensitivity consistent with the literature. These data were difficult to interpret, however, because of a confound of age. We will need to age-match our groups before drawing any major conclusions. That said, we found a significant positive correlation between measures of recollection on both the AI and ROC task, which was a promising finding in terms of validating the new measure against an established procedure. Overall, our results suggest that assessing recall and recognition for a staged event is a viable method for studying naturalistic memory.

The current study introduced a new measure for the study of naturalistic memory, which involved the use of a homogeneous, controlled event for all participants. We tested participants’ memory for this so-called staged event with both the Autobiographical Interview (AI) and our novel receiver operating characteristic (ROC) task. Statistical analyses indicated that scores on the AI and on our new ROC measure showed time sensitivity consistent with the literature. These data were difficult to interpret, however, because of a confound of age. We will need to age-match our groups before drawing any major conclusions. That said, we found a significant positive correlation between measures of recollection on both the AI and ROC task, which was a promising finding in terms of validating the new measure against an established procedure. Overall, our results suggest that assessing recall and recognition for a staged event is a viable method for studying naturalistic memory.

Memory is an essential component for learning. Deficits in verbal short-term memory (STM) and working memory (WM) are thought to hinder language learning, reading acquisition, and academic achievement. The Children’s Memory Scale (CMS) is an assessment instrument used to identify memory and learning deficits and strengths in children ages five through 16. This study investigated the impact of culture and parent educational level (PEL) on student performance on the Children’s Memory Scale using the CMS standardization data. The major question addressed was: Will CMS subtest performance differ significantly between ethnic groups or as a function of PEL? The results of this study support a relationship between STM and WM performance and culture. Culture as defined by ethnicity minimally impacted student subtest performance on the CMS when PEL was taken into account. In contrast, PEL was significantly associated with student subtest performance within each ethnic group. Student subtest performance improved with each increase in PEL regardless of ethnicity. CMS subtest performance of Hispanic and African American students was most affected by PEL; however, no difference occurred in subtest performance by ethnicity or as a function of PEL for African American and Hispanic students on the Family Pictures subtest which examines visual and auditory memory processes through recall of everyday life tasks in meaningful context. Although statistical significance was found between CMS subtest performance and cultural factors, the effect sizes were mainly in the small range and variance was not specific to any one subtest. Larger effect sizes were found on verbal subtests which in previous studies have been found to be most impacted by quality of schooling and lower PELs. Mean score differences did not exceed one standard deviation with the exception of one subtest. The results of this study provide a better understanding of the effect of culture and PEL on memory and learning.

Along with process technology advancement, we can integrate more and more on-chip memory in an SOC. Memory intensive applications, such as image processing and digital signal processing, usually access certain number of data arrays. Memory system designs for such systems can then critically influence cost, performance, and power of the resulting SOCs. In this thesis research, we focus on the software design of a memory synthesis method of data stored in arrays. Memory synthesis task considers access time, power, and cost requirements of array data and utilize characteristics of indexing patterns of array accesses. It then derive the allocation of memory organizations and effective organizations of multiple data arrays mapped onto the allocated memory modules. Its design principle lies in the matching of data array reorganization and their assigned memory module resource allocation so as to enhance data access locality in the same memory rows and to reduce the number of row accesses (bit line accesses). Hence, we can achieve required power and performance goals with low memory system cost. Static memory synthesis solves memory synthesis problem with fixed loop count and tasks in prior of product design. The memory synthesis task succeeds the high level synthesis task. It is then followed by the address generating circuit design task and the memory access scheduling circuit design task of the functional module side. These circuit designs can herein be combined with high level synthesis results to perform logic synthesis. Finally, we can perform physical synthesis of functional modules, logic circuit modules, and memory modules. It is thus expected to produce an SOC design satisfying overall design requirements. The software design of the static memory synthesis method includes two main topics: memory allocation and module assignment for data arrays and the estimation method of a memory system design. In this research, we designed the experimental software for the memory synthesis method. We also planned experiments based upon real and synthetic design cases to validate the effectiveness of the static memory synthesis method.

Memory refers to the retention of learned information or experiences in the brain. It is known that interference of certain brain functions immediately after training or memory reactivation can cause memory loss (i.e. amnesia). The post-training process is called consolidation and the post reactivation process is called reconsolidation. However, it remains unclear as to: (1) whether appetitive, goal-directed memories undergo reconsolidation, (2) whether overtrained memories undergo reconsolidation, (3) what the nature of amnesia is (i.e. whether it represents storage or retrieval impairment), (4) how to test the nature of amnesia, and (5) whether the brain uses the same mechanism for a new learning and from a second learning. This thesis, composed of five manuscripts, aims to answer these questions. In the first manuscript, the model of incentive learning of appetitive outcomes in instrumental conditioning was used. Protein synthesis inhibitor (PSI) was infused into lateral and basal amygdala (LBA) after the new incentive learning and after the reactivation of the memory. The results show that appetitive memories in controlling goal-directed behaviors underwent consolidation and reconsolidation in the LBA. In the second manuscript, rats were overtrained with auditory fear conditioning and received intra-LBA PSI infusions after memory reactivation. The results show that only old, but not recent, overtrained auditory fear memories underwent reconsolidation. This suggests overtraining sets a boundary condition on memory reconsolidation. Further results showed dorsal hippocampus and intra-LBA NR2B-subunit containing N-methyl-D-aspartic acid receptors (NMDAr) were involved in this boundary condition. In the third manuscript, the unresolved debate about the nature of amnesia was reviewed from a historical perspective and the suggestions on reconciling this issue are proposed. In the fourth manuscript, a new approach was used to test the nature of amnesia in contextual fear conditioning. Because NMDAr blockade impairs a new learning but not a second learning, it is predicted that if a memory is not stored then the second learning should be impaired by NMDAr blockade. The results suggest amnesia of contextual fear memory caused by intra-dorsal hippocampus (dH) PSI infusion represents a storage impairment which gives a different result from extinction induced irretrievability. In the fifth manuscript , the aim is to identify the brain mechanism for the second learning as the previous manuscript suggests it is different from the first learning mechanism. The results show that the first, but not the second learning required voltage-dependent calcium channels and activation in dH. The second learning was impaired by intra-dH or ventral hippocampus (vH) inactivation only when the protein synthesis in the other portion of hippocampus was blocked after training. This suggests while the first learning by default requires dH, the second learning can be acquired through a functional dH or vH. In summary, this thesis extends memory research from consolidating a new learning to characterizing the reconsolidation of appetitive and overtrained memory to consolidating a second learning which will lead to a more complete description of memory process.

Thesis (Ph.D.)--Australian National University, 2005.

Issued also as Thesis (Ph. D.)--Columbia University. / Bibliography: p. 55-56.