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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Design and Applications of Low-Power Memory Generators

Tsung, Chih-qu 03 September 2008 (has links)
Memory unit has become a major core component in most SoC designs, and thus reusable memory IP is crucial in speeding up the design process. In this thesis, we develop a low-power SRAM generator to reduce the design efforts by producing all the files required in traditional cell-based design flow. Several methods are used to reduce power consumption in the memory circuits, including hierarchical word-line architecture and block amplifiers. The SRAM generator can be extended to generate cache memory with mixed hard IP and soft IP where cache memory cells are hard IP while the cache controller is soft IP. Based on the SRAM generator, we can also generate some popular memory units such as register files, FIFO, LIFO, and delay elements used in many applications.
2

Visual confusions in immediate memory.

Hiles, David Roger. January 1971 (has links)
No description available.
3

Brain Regions Involved in Long-term Spatial Memory: fMRI and Behavioural Studies

Hirshhorn, Marnie 24 July 2013 (has links)
In this thesis, I investigated the role of the hippocampus and other brain regions in long-term spatial memory. I used neuroimaging and behavioural techniques to compare spatial representations that are dependent on the hippocampus and those that rely on extra-hippocampal structures. In Experiment 1, I demonstrated that at least some spatial memories that are initially dependent on the hippocampus can become independent of it with time. This was done by looking at changes in brain activation as participants became familiar with a real-world environment over a year. Hippocampal activation was found during mental navigation tasks when participants were new to Toronto, but not after they had lived there for a year. This change was accompanied by an increase in activation in the posterior parahippocampal gyrus, lingual gyrus, cuneus, and superior temporal gyrus. In Experiment 2, I used neuroimaging to compare hippocampal involvement during the retrieval of coarse- and fine-grained spatial details, and episodic details associated with a familiar environment. I showed that hippocampally-mediated representations contain more fine-grained spatial details than extra-hippocampal spatial representations. Further, I demonstrated that fine-grained details become less dependent on the hippocampus with experience, but episodic details require the hippocampus throughout the lifetime of the memory. In Experiment 3, I provided behavioural evidence that the role of hippocampus in episodic memory associated with a familiar environment is crucially related to the degree of detail retrieved. Older adults were asked to recall walking routes from their daily lives and the number of details retrieved was correlated with tests sensitive to hippocampal function. Finally, I showed that the extra-hippocampal regions implicated in spatial memory depend on task demands. Basic navigation can be supported by the posterior parahippocampal gyrus, lingual gyrus, superior temporal gyrus, caudate and inferior frontal gyrus, independently of the hippocampus. When navigation requires fine-grained spatial details, additional regions including the precuneus and supramarginal gyrus will be recruited. When the task requires the retrieval of episodic details, the posterior cingulate, angular gyrus, and medial frontal lobes will be required, along with the hippocampus.
4

The assessment of very long-term memory using the questionnaire technique : a replication and extension

Czerwinski, Mary P. January 1983 (has links)
A replication and extension of a questionnaire technique for assessing very long-term memory is described. A 90-item questionnaire containing items from five different categories was administered to an Introductory Psychology class consisting of 90 females and 57 males. Results from each of the five categories revealed deviations from a linear trend in the recognition scores of items for a given year. Also, the results indicated that large proportions of the variance were due to the stimulus items used for that particular category. A post hoc test was included for two of the categories which tested the relationship between the number of references an item received in the New York Times Index with its recognition score on the questionnaire. A significant relationship was found and this evidence was used to support the hypothesis that the more available an item is to the general public, the more recognizable or distinctive it becomes. This distinctiveness causes the item to be resistant to memory decay and more recognizable, regardless of age.
5

Expectations modulate early but not late event-related potential correlates of successful recognition memory

Knight, Emily E. 07 November 2014 (has links)
Recognizing that an item has been previously encountered may not only depend on the strength of memory for that item, but also the expectation that the item will be remembered. Recent studies by O’Connor, et al (2010) and Jaeger et al (2013) revealed that a significant portion of the functional magnetic resonance imaging (fMRI) “retrieval success” effect (BOLD signal for correctly identified old items > new items) depends upon whether participants expect novel or familiar stimuli. The current study examined how expectancy modulates the event-related potential (ERP) retrieval success effect. We employed a typical recognition memory task with the addition of explicit cues indicating if upcoming memory probes were “likely old”, “likely new” (with 75% validity), or “unknown”. An electrophysiological response to the cue, primarily across frontal electrodes from 700-850ms after cue onset, predicted individual differences in cue- induced bias in memory judgments. Responses to memory probes were examined 300- 400ms and 500-700ms after probe onset, corresponding to time windows previously associated with ERP correlates of memory processing. Differences between old and new items were greatest from 300-400ms when preceded by “likely old” cues, overlapping with a component previously identified as tracking familiarity-based processing. In contrast, the 500-700ms time window, previously associated with recollection, revealed significant differences between old and new items that were not modulated by cue type. Overall this pattern of results shows that cue induced biases influence earlier (300-400ms after onset of a memory probe) but not later retrieval processing (500-700ms). / text
6

The relationship between specific memory recall and future event processing

Leung, Wing-in, 梁穎妍 January 2014 (has links)
The present study aims at examining the relationship between specific memory recall and future event processing. Previous research suggested that the ability in generating specific future events was closely linked with recalling specific past memories. A total of 73 participants (40 in depressed group and 33 healthy control group) completed a specific memory recall and a future event generation task with emotional cues (positive and negative) and a neutral cue. The number of specific responses generated and the mean specific memory latency were recorded for analysis. Result not only replicated previous findings that the depressed group demonstrated more difficulties in generating specific responses, it also provided new insight in exploring the relationship between specific memory recall and future events processing. Firstly, the result indicated that the number of specific responses was fewer and the mean latency of specific responses was longer in generating future events than recalling specific memories. Secondly, the number and the mean latency of specific responses depended on different emotional loaded cues. Further discussion was focused on the valence effect on specific responses. Lastly, it was revealed that depressed patients had a particular difficulty in generating positive future events. Discussion was emphasized on the emotional loaded effect and hopelessness. Both theoretical and clinical implicated were suggested based on the new findings. / published_or_final_version / Clinical Psychology / Master / Master of Social Sciences
7

Interference effects in short-term motor memory

Pepper, Ross Laurence January 1969 (has links)
Typescript. / Bibliography: leaves [146]-151. / x, 151 l illus
8

Brain Regions Involved in Long-term Spatial Memory: fMRI and Behavioural Studies

Hirshhorn, Marnie 24 July 2013 (has links)
In this thesis, I investigated the role of the hippocampus and other brain regions in long-term spatial memory. I used neuroimaging and behavioural techniques to compare spatial representations that are dependent on the hippocampus and those that rely on extra-hippocampal structures. In Experiment 1, I demonstrated that at least some spatial memories that are initially dependent on the hippocampus can become independent of it with time. This was done by looking at changes in brain activation as participants became familiar with a real-world environment over a year. Hippocampal activation was found during mental navigation tasks when participants were new to Toronto, but not after they had lived there for a year. This change was accompanied by an increase in activation in the posterior parahippocampal gyrus, lingual gyrus, cuneus, and superior temporal gyrus. In Experiment 2, I used neuroimaging to compare hippocampal involvement during the retrieval of coarse- and fine-grained spatial details, and episodic details associated with a familiar environment. I showed that hippocampally-mediated representations contain more fine-grained spatial details than extra-hippocampal spatial representations. Further, I demonstrated that fine-grained details become less dependent on the hippocampus with experience, but episodic details require the hippocampus throughout the lifetime of the memory. In Experiment 3, I provided behavioural evidence that the role of hippocampus in episodic memory associated with a familiar environment is crucially related to the degree of detail retrieved. Older adults were asked to recall walking routes from their daily lives and the number of details retrieved was correlated with tests sensitive to hippocampal function. Finally, I showed that the extra-hippocampal regions implicated in spatial memory depend on task demands. Basic navigation can be supported by the posterior parahippocampal gyrus, lingual gyrus, superior temporal gyrus, caudate and inferior frontal gyrus, independently of the hippocampus. When navigation requires fine-grained spatial details, additional regions including the precuneus and supramarginal gyrus will be recruited. When the task requires the retrieval of episodic details, the posterior cingulate, angular gyrus, and medial frontal lobes will be required, along with the hippocampus.
9

An analysis and test of the reconstructive-schematic model of memory

Creighton, David Joseph January 1978 (has links)
The present study involved a test of the reconstructive-schematic model of memory. This model is presented within the historical context in which it developed, with the emphasis being placed on Piaget's research. The reconstructive-schematic model is analyzed and its two key assumptions concerning the nature of memory and recall are isolated. Thus according to this model: (1) representation is closely linked and dependent upon the nature of perception. The active role of the individual during perception is of critical importance as representation and recall are determined by the individual's analysis of the stimuli, during perception. (2) Memory involves a conservation of "rules" in schematic form and recall is characterized by a reconstructive process in which these rules are used to reconstruct the original stimulus as adequately as possible. To test these two assumptions an incidental learning paradigm involving two different orienting tasks was used. Twelve series of pictures per series comprised the visual stimuli which were employed in this study. Six: groups of seventeen volunteer university students per group were tested. Three groups solved an analogy orienting task while three groups completed a ranking orienting task. In Piagetian terminology, the analogy orienting task was assumed to emphasize the "operative" aspect of cognition while the ranking task emphasized the "figurative" aspect. All six groups were tested for free recall one week after performing the orienting tasks. Two groups (AImm and RImm) were tested for free recall immediately after completing the orienting tasks. Four of the groups (AImm and RImm as well as AWk and RWK, two. groups not tested for immediate free recall) were tested for probed, recall immediately after completing the delayed free recall test. Finally, two groups (ARec and RRec) received a recognition test instead of the probed recall test. To test all predictions that followed from the two major assumptions of the reconstructive-schematic model, it was necessary to conduct two different phases of analysis. The first phase focused on the subjects' performance on the dependent variables: immediate, final free, and probed recall, "clustering", "component clustering", time spend solving orienting task, and recognition. In the second phase, the scores on each dependent variable were collapsed across subjects, resulting in a mean score for each of the seven positions in each of the series. This type of analysis was required to examine the "pattern" or organization of free recall, probed recall, and clustering scores. In both phases, one way analyses of variance were conducted for each dependent variable and each comparison under consideration. The first assumption was supported by the finding that the "pattern" of immediate, final free, and probed recall scores and recognition scores varied with the type of orienting task involved. The second assumption received support from the finding that the "analogy" groups were characterized by greater clustering and probed recall scores and fewer errors during final free recall. However, contrary to predictions, the analogy groups were not characterized by greater free recall. / Arts, Faculty of / Psychology, Department of / Graduate
10

Effects on sentence recall of varying age : mean depth, and sentence type.

Mitchell, Diana Lee January 1968 (has links)
The purpose of this study was to investigate the effects on recall of varying sentence complexity, sentence type, and age of the subjects. The measure of sentence complexity used was Martina and Roberts’ (1966) adaptation of Yngve's (1960) depth. The six sentence types involved were kernel (K), negative (N), passive (P), negative-passive (NP), passive truncated (PT), and negative-passive truncated(NPT). One hundred twenty children, and one hundred twenty adults, were exposed, ten at a time, to an orally-presented example of each sentence type. After hearing the six sentences, the subjects were instructed to write as many as they could recall. Six such trials were effected with each subject. Twelve sets of six sentences each were used such that six sets were of the lesser mean depth (1.29) and six sets were of the greater mean depth (1.71). Sixty subjects of each age were exposed to one of either the six sets of sentences having mean depth 1.29, or to one of the six sets of sentences having mean depth 1.71. The data supported two of three stated hypotheses, that is: i) The likelihood of recall of a sentence is inversely related to the mean depth of that sentence when both children and adults are subjects. ii) More sentences of all types and of either depth are recalled by adults than by children. A third hypothesis that: iii) Kernel sentences are recalled better than non-kernel sentences by children and adults, was not supported by the data. It was found, rather, that both adults and children correctly recalled sentences involving the negative better than those which did not. This finding, although supported by neither psycholinguistic theory nor by the experimental literature, was interesting. It was suggested that a study be performed in an attempt to reproduce these results, and that an investigation be made to determine if a tendency to respond correctly more often to negative stimuli Is a culturally-determined factor. Further, it was suggested that study be made of the significance of the mean depth factor, of transformations, and of their interaction. / Arts, Faculty of / Psychology, Department of / Graduate

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