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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.
11

The hippocampus and entorhinal cortex map events across space and time

Bladon, John Hodgetts 14 June 2019 (has links)
The medial temporal lobe supports the encoding of new facts and experiences, and organizes them so that we can infer relationships and make unique associations during new encounters. Evidence from studies on humans and animals suggest that the hippocampus is specifically required for our ability to form these internal representations of the world. The mechanism by which the hippocampus performs this function remains unclear, but electrophysiological recordings in the hippocampus support a general model. One component of this model suggests that the cortex represents places, times, and events separately, and then the hippocampus generates conjunctive representations that connect the three. According to this hypothesis, the hippocampus binds places and events to an existing relational structure. This dissertation explores how item and place associations develop within cortex, and then examines the relational structure that organizes these events within the hippocampus. The first study suggests that contrary to previous models, events and places are bound together outside of the hippocampus in the entorhinal cortex and perirhinal cortex. The second study shows that this relational scaffold may be embodied by a continually changing code that permits both the association and separation of information across the continuum of time. The final study suggests that the hippocampus and entorhinal cortex contain qualitatively different time codes that may act in a complementary fashion to bind events and places and relate them across time. Overall, these studies support a theory wherein time is encoded in a range of brain regions that also contain conjunctive item and position information. In these regions, conjunctive representations of items, places, and times are organized not only by their perceptual similarity but also their temporal proximity.
12

Behavioral and Electrophysiological Evidence for Hippocampal Involvement in Object Motion Processing in C57BL/6J Mice

Unknown Date (has links)
Considerable research has been carried out to establish a rodent model for the study of human memory, yet functional similarities between the species remain up for debate. The hippocampus, a region deep within the medial temporal lobe of the mammalian CNS, is critical for long-term episodic memory. Projections from the medial entorhinal cortex convey spatial/contextual information, while projections from the lateral entorhinal cortex convey item/object information to the hippocampus. The functional significance of these parallel projections to the rodent hippocampus has been suggested to support spatial processing, while the same projections to the human hippocampus support spatial and non-spatial memory. Discharging in a location-specific manner, hippocampal place cells contribute to spatial memory; however, evidence for neuronal correlates of non-spatial object memory has not been fully defined. The current experiments were designed to address the following questions, while utilizing electrophysiology, functional inactivation during a novel behavioral task, and immunohistochemistry. Is the memory for objects hippocampal-dependent, solely due to the location of the object, or are objects represented within hippocampal activity independent of location? To tease apart spatial and non-spatial processing by the hippocampus, the spatial aspects of 3D objects were enhanced by utilizing movement. A novel discriminatory avoidance task, Knowing Your Enemy, was adapted from an Enemy Avoidance task to test true object memory in mice. Current findings support the notion that object-associations acquisition depends upon a specific context. Retrieval of such object-associations is not context-dependent, yet remains sensitive to temporary inactivation of the CA1 region of the dorsal hippocampus. The avoidance impairments observed following hippocampal inactivation were shown to not be a result of reduced anxiety. Immunohistochemical marker expression suggests that the CA1 region was highly active during object exposures, yet the hippocampal system responded differentially to moving and to stationary objects. Recordings of CA1 neurons yielded non-bursting object-related activity during object exploration, and place cell activity remained unaffected in the presence of moving objects; supporting independent, yet simultaneous processing of spatial and non-spatial information within the hippocampus. Together, the current findings support the notion that the CA1 region of the rodent hippocampus processes object-related information, independent of spatial information. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection
13

Product Placement: Implicit Memory and Choice for Brands Placed in a Novel

Manzano, Isabel 2010 August 1900 (has links)
Product placement, an advertising trend that places a brand within the context of an information medium, has emerged as an effective means of increasing brand recognition. The practice has not been thoroughly examined in the different media in which it occurs. The purpose of the present experiment was to investigate the effectiveness of prominent and subtle product placements in books on different forms of memory. The effectiveness of the placements was evaluated by measuring explicit and implicit memory for the placed brands. Additionally, effectiveness was measured with two types of preference judgments: a forced choice scenario and a shopping list scenario. Results from Experiment 1 showed that participants demonstrated implicit memory for brands mentioned in the novel with a word stem completion task and a category exemplar generation task. The centrality of placement only affected performance on these tasks for test-aware participants. Experiment 2 used a forced choice task and showed that consumer preference was unaffected by subtle and prominent placements. Experiment 3 used a shopping list scenario and showed that brand placement affected participants’ preferences for previously studied brands regardless of the placement centrality. The experiments also showed that participants had explicit memory for the brands with prominent placements leading to better recall than subtle placements. Taken together, the findings show that the placement of brands in books is a valid means of influencing consumer awareness and behavior toward the brand.
14

The implicit and explicit memory of static and interactive objects in virtual reality

Olsson, Petra January 2019 (has links)
Virtual reality applications are developing fast and break new grounds every day in new industries. In today's market, most of the virtual reality projects are funded by venture capitalists and are yet to produce any revenue. For an advertiser to be willing to advertise they must see some sort of value or possibility to receive revenue out of the intended commercial. Memory is a common measure of influence from a commercial. Therefore, this thesis aim was to investigate if the memory, in terms of implicit and explicit memory, was affected by objects with different levels of interaction in virtual reality. A user study was conducted where the participants were instructed to go through several virtual rooms, where they were exposed to static, semiinteractive and interactive objects in the categories fruits/vegetables and beverage cans. The static objects were presented as pictures on instruction boards, the semi-interactive objects were presented through point-and-click tasks, and the interactive objects were presented through tasks that utilized body movements in virtual reality.When the participants were finished with the virtual reality application, they conducted a survey regarding their experiences and was asked to fill out three memory tests; a word-fragment completion task, a cued recall test, and a recognition task. Results show that interactive and semi-interactive objects in virtual reality did have a significant impact on explicit memory, and that the static objects did not. For implicit memory a conclusion could not be drawn whether the objects in the virtual environment had any impact due to no significant difference between the study participants and the control group without influence of the study as a result of not enough data. The results from the study were vastly different for fruits/vegetables and beverage brands, where results for the fruits/vegetables had a clear distinction and the beverage brands had almost no significant data, which could be due to “Inattentional blindness”. / Virtuella verklighets (Virtual reality) applikationer utvecklas snabbt och bryter ny mark varje dag i nya industrier. På dagens marknad, så är de flesta virtuella verklighets projekten finansierade av riskkapitalister och är fortfarande i ett läge där de inte producerar intäkt. For att marknadsförare ska vara villiga att investera måste de se någon potential i att få intäkter från den avsedda reklamen. Minne, är ett vanligt mått för att mäta påverkan av en reklam. Därav var avsikten for denna avhandling att undersöka om minnet, i form av implicit och explicit minne, blev påverkat av objekt med olika nivåer av interaktion i en virtuell verklighet. Ett användartest utfördes där deltagare blev instruerade att gå genom flera virtuella rum, där de blev exponerade för statiska, semi-interaktiva och interaktiva objekt i kategorierna frukter/grönsaker och dryckesmärken. De statiska objekten representerades som bilder på en statisk instruktionstavla, dom semi-interaktiva objekten representerades genom en peka-ochklicka uppgift, och de interaktiva objekten var representerade genom uppgifter som utnyttjade kroppsrörelser i en virtuell verklighet.När deltagarna fullföljt den virtuella verklighets applikationen fick de fylla i en enkät angående deras upplevelser, samt fylla i tre minnes test; ett ord-fragmentkompletterings test, ett indikation återkallelsetest, och ett igenkännings test. Resultaten visar på att de interaktiva och de semi-interaktiva objekten i den virtuella verkligheten hade en signifikant påverkan på det explicita minnet, samt att de statiska inte hade det. För de implicita minnet kunde inga slutsatser dras huruvida objekten i den virtuella verkligheten hade någon inverkan på grund av ingen signifikant skillnad mellan studiedeltagarna och kontrollgruppens resultat som en efterföljd av otillräckliga data. Resultaten från studien hade olika utfall för frukter/grönsaker och dryckesmärken, där resultaten för frukter/grönsaker hade en klar distinktion, medan dryckesmärkena hade nästan ingen signifikant data, vilket kan bero på ”Ouppmärksam blindhet” (Inattentional blindness).
15

<b>FACILITATING SENTENCE PROCESSING IN APHASIA: EVIDENCE FROM SELF-PACED READING</b>

Grace Hoi-Yan Man (17565099) 07 December 2023 (has links)
<p dir="ltr">It is well known that persons with aphasia (PWA) demonstrate deficits in sentence processing. Specifically, many show difficulties with syntactic re-analysis, or the ability to revise one’s interpretation of a sentence due to a temporary ambiguity. Emerging evidence suggests that structural priming, individuals’ tendency to unconsciously re-use a previously encountered structure, can facilitate production and comprehension of different sentence structures in PWA. However, there are inconsistencies within the literature regarding the robustness of priming across different sentence structures and tasks, and the existing findings are limited to off-line measures which do not capture real-time sentence processing. Furthermore, a range of individual variability has been shown in magnitudes of priming effects.</p><p dir="ltr">This current project addressed these critical gaps by investigating the effects of structural priming on comprehension of sentences with reduced relative (RR) clauses. Study 1 examined whether PWA show immediate structural priming and longer-term cumulative priming in a computerized self-paced reading paradigm. In this study, participants read RR target sentences that were preceded by prime sentences with either an RR or a main clause (MC) interpretation. Study 2 examined if and how individuals’ cognitive (memory) skills account for individual variability shown in structural priming. Participants completed a Serial Reaction Time task as a measure of implicit memory, and the Verbal Paired Associates I task as a measure of explicit memory. Eighteen healthy adults (HA) and 18 PWA participated in both studies.</p><p dir="ltr">In Study 1, PWA demonstrated robust and timely immediate structural priming effect, providing novel evidence that structural priming can be captured in real-time using self-paced reading, and that priming can help ameliorate syntactic re-analysis deficits in PWA. However, these online changes were not reflected in the behavioral measures, highlighting the sensitivity of self-paced reading in detecting the dissociation between automatic, real-time processing and overt behavioral responses. Cumulative priming as traditionally defined was also not significant for either group, although participants became faster at reading RR target sentences as the session progressed. Study 2’s findings suggest that implicit memory may be an important cognitive skill to promote sentence processing, whereas having strong explicit memory may not be facilitative of the learning process.</p>
16

Beyond dissociation : exploring interactions between implicit priming and explicit recognition

Park, Joanne L. January 2013 (has links)
Over the last 30 or more years evidence has accumulated in favour of the view that memory is not a unitary faculty; rather, it can be subdivided into a num- ber of functionally independent subsystems. Whilst dividing memory phenomena into these distinct subsystems has undoubtedly advanced our understanding of memory as a whole, the approach of studying subsystems in isolation fails to address potential interactions between them. Over the last few decades there has been a gradual increase in the number of studies attempting to move be- yond dissociation by characterising functional interactions between subsystems of memory. The main aim of this thesis was to contribute to this endeavour, by examining interactions between two specific subsystems that are positioned on opposite sides of the declarative and non-declarative divide in long-term mem- ory: priming and episodic recognition. Event-Related Potentials (ERPs) were employed to monitor neural markers of repetition priming and episodic memory during recognition tests with masked priming of test cues. In the standard pro- cedure, half of the studied and unstudied test trials began with a brief (48ms) masked repetition of the to-be-recognized word prior to the onset of test items; the remaining unprimed trials were preceded by the word “blank”. The pattern of priming effects across experiments was reasonably consistent, with differences between experiments directly related to the intended manipulations. In contrast to priming effects, the pattern of memory effects was variable across experiments, demonstrating that the engagement of explicit recognition signals is influenced by the outcome of implicit processing, and suggesting that interactions between priming and explicit retrieval processes do occur. Taken together, results from experiments reported in this thesis indicate (1) that under certain circumstances, priming is sufficient to support accurate recognition and does not necessitate changes in memory performance, (2) that mid-frontal old/new effects indexing familiarity are not merely driven by repeated access to semantic information, and (3) that priming influences neural correlates of recollection by speeding their onset. Overall, the data clearly demonstrate that there are multiple potentially interacting routes to recognition.
17

The Role of Cognitive Processes in Eating Pathology

Johansson, Linda January 2006 (has links)
<p>Researchers have recently combined clinical and cognitive areas of research in order to investigate the role of cognitive factors in explaining how emotional disorders are developed and maintained. It is believed that biased cognitive processing of emotionally relevant information can greatly affect emotional responses and behaviour where insights into such cognitive processes can have invaluable clinical implications.</p><p>The present thesis investigates the role of cognitive biases for information related to food and body appearance in individuals with eating disorders (ED) and those with non-clinically eating disorder-related concerns (NED). Are ED characterised by cognitive biases toward such information related to their specific concerns? Are such cognitive biases specific to clinical ED or present also in NED samples? Are cognitive biases operating at both conscious and unconscious levels of cognitive processing?</p><p>The tasks used to pursue these questions were: the emotional Stroop task, an Internet version of the emotional Stroop, Jacoby’s white noise paradigm and a recognition task. The influence of priming on the emotional Stroop task was also investigated in order to test whether the use of this task could be extended to more complex investigations than selective attention.</p><p>Results provide support for that cognitive processing of information related to eating and body appearance is biased in individuals with ED. It is, however, unclear whether such biased processing is specific to clinical ED. Findings further suggest that cognitive biases occur primarily at unconscious levels of cognitive processing. Support was also obtained for that the emotional Stroop task is sensitive to priming where initial body perception may be one factor influencing cognitive responses toward negative self referent words following exposure to thin ideal images. Results further suggest that the emotional Stroop task successfully can be administered via the Internet where manipulating task delivery and response mode may increase the sensitivity of this task. Some of the advantages of administering the emotional Stroop task via Internet over traditional methods are access to more heterogeneous samples, more ecologically valid situations, reduced costs and minimisation of demand characteristics.</p>
18

The Role of Cognitive Processes in Eating Pathology

Johansson, Linda January 2006 (has links)
Researchers have recently combined clinical and cognitive areas of research in order to investigate the role of cognitive factors in explaining how emotional disorders are developed and maintained. It is believed that biased cognitive processing of emotionally relevant information can greatly affect emotional responses and behaviour where insights into such cognitive processes can have invaluable clinical implications. The present thesis investigates the role of cognitive biases for information related to food and body appearance in individuals with eating disorders (ED) and those with non-clinically eating disorder-related concerns (NED). Are ED characterised by cognitive biases toward such information related to their specific concerns? Are such cognitive biases specific to clinical ED or present also in NED samples? Are cognitive biases operating at both conscious and unconscious levels of cognitive processing? The tasks used to pursue these questions were: the emotional Stroop task, an Internet version of the emotional Stroop, Jacoby’s white noise paradigm and a recognition task. The influence of priming on the emotional Stroop task was also investigated in order to test whether the use of this task could be extended to more complex investigations than selective attention. Results provide support for that cognitive processing of information related to eating and body appearance is biased in individuals with ED. It is, however, unclear whether such biased processing is specific to clinical ED. Findings further suggest that cognitive biases occur primarily at unconscious levels of cognitive processing. Support was also obtained for that the emotional Stroop task is sensitive to priming where initial body perception may be one factor influencing cognitive responses toward negative self referent words following exposure to thin ideal images. Results further suggest that the emotional Stroop task successfully can be administered via the Internet where manipulating task delivery and response mode may increase the sensitivity of this task. Some of the advantages of administering the emotional Stroop task via Internet over traditional methods are access to more heterogeneous samples, more ecologically valid situations, reduced costs and minimisation of demand characteristics.
19

An examination of adult age differences in implicit and explicit memory for prescription drug advertisements

Abernathy, L. Ty January 2008 (has links)
Thesis (Ph.D.)--Mississippi State University. Department of Psychology. / Title from title screen. Includes bibliographical references.
20

Bringing very long term memories back to life / Réveiller nos mémoires les plus anciennes

Larzabal, Christelle 07 July 2017 (has links)
On pense souvent que notre mémoire nous joue des tours et nous fait défaut. Ces oublis concernent généralement des souvenirs qui ne sont pourtant pas si vieux. Alors quand il s’agit de se rappeler d’informations sensorielles auxquelles nous n’avons pas repensé depuis plusieurs dizaines d’années, pas de doute, il ne reste plus rien… Mais en est-on vraiment sûr? Et si l’information était toujours là, prête à se manifester de manière explicite -comme sous forme de rappel ou de sentiment de familiarité- pour peu que les conditions le lui permettent? A ce jour, très peu d’expériences ont été menées sur ce sujet. L’objectif de ma thèse a donc été d’apporter des premiers éléments de réponse concernant la récupération de mémoires laissées inactives. Ma recherche s’est orientée selon deux axes principaux : une première partie théorique où je montre a) qu’il n’est pas nécessaire de réactiver une trace mnésique pour la maintenir à très long-terme si elle a été suffisamment répétée et b) que la récupération explicite de cette mémoire serait possible grâce à la présentation d’informations qui cibleraient au mieux le souvenir ; une seconde partie expérimentale où je montre a) que des participants sont capables de récupérer de manière explicite des informations laissées en dormance pendant au moins une dizaine d’années et b) que cette trace mnésique pourrait être détectée sur des tracés d’Electroencéphalographie (EEG). Ainsi, et aussi étonnant que cela puisse paraître, dans des conditions favorables à leur réactivation, d’anciennes traces mnésiques que l’on croyait disparues, peuvent de nouveau surgir sous la manifestation de rappel ou de sentiment de familiarité par exemple. Ces résultats soulèvent des questions majeures concernant le stockage neuronal de cette information. / Memory plays tricks on us and fails us even for recent events. So for the retrieval of sensory information that we have not experienced for decades, surely the memories are gone without a trace, but can we be sure of this? What if the information had been there all along ready to be explicitly retrieved through recall or familiarity for example? So far, experimental evidence is lacking. The purpose of my thesis was to shed some light on the retrieval of these inactive memories. To tackle this problem I developed my research around two main axes: For the first part which is theoretical, I suggest that a) reactivations are not necessary to maintain very long-term memories if the memories were sufficiently repeated at first; b) it might be possible to retrieve explicitly remote inactive memories using specific cues; in the second part which is experimental, I show that a) within specific conditions participants are able to retrieve explicitly very long-term memories that were left inactive for decades and b) such memory traces could be found on the Electroencephalography (EEG) signals. Surprisingly, when conditions are met, remote memories that were thought to be lost can again elicit recall or familiarity. With these results, a question remains: How do neurons store such information?

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