Cognitive set, absorption, and achievement as moderators of the perceptual closure effect in picture priming /

The present study examined individual differences in Absorption and fantasy, as well as in Achiievement and achievement striving as possible moderators of the perceptual closure effect found by Snodgrass and Feenan (1990). The study also examined whether different instructions (experiential versus instrumental) interact with the personality variables to moderate the relationship between priming and subsequent performance on a picture completion task. 1 28 participants completed two sessions, one to fill out the MPQ and NEO personality inventories and the other to complete the experimental task. The experimental task consisted of a priming phase and a test phase, with pictures presented on a computer screen for both phases. Participants were shown 30 pictures in the priming phase, and then shovm the 30 primed pictures along with 30 new pictures for the test phase. Participants were randomly assigned to receive one of the two different instruction sets for the task. Two measures of performance were calculated, most fragmented measure and threshold. Results of the present study confirm that a five-second exposure time is long enough to produce the perceptual closure effect. The analysis of the two-way interaction effects indicated a significant quadratic interaction of Absorption with priming level on threshold performance. The results were in the opposite direction of predictions. Possible explanations for the Absorption results include lack of optimal conditions, lack of intrinsic motivation and measurement problems. Primary analyses also revealed two significant between-subject effects of fantasy and achievement striving on performance collapsed across priming levels. These results suggest that fantasy has a beneficial effect on performance at test for pictures primed at all levels, whereas achievement striving seems to have an adverse effect on performance at test for pictures primed at all levels. Results of the secondary analyses with a revised threshold performance measure indicated a significant quadratic interaction of Absorption, condition and priming level. In the experiential condition, test performance, based on Absorption scores for pictures primed at level 4, showed a positive slope and performance for pictures primed at levels 1 and 7 based on Absorption showed a negative slope. The reverse effect was found in the instrumental condition. The results suggest that Absorption, in combination with experiential involvement, may affect implicit memory. A second significant result of the secondary analyses was a linear three-way interaction of Achievement, condition and priming level on performance. Results suggest that as Achievement scores increased, test performance improved for less fragmented primed pictures in the instrumental condition and test performance improved for more highly fragmented primes in the experiential condition. Results from the secondary analyses suggest that the revised threshold measure may be more sensitive to individual differences. Results of the exploratory analyses with Openness to Experience, Conscientiousness and agentic positive emotionality (PEM-A) measures indicated no significant effects of any of these personality variables. Results suggest that facets of the scales may be more useful with regard to perceptual research, and that future research should examine narrowly focused personality traits as opposed to broader constructs.

Le blocage de la consolidation et de la reconsolidation des souvenirs émotionnels chez l'humain à l'aide du propranolol

Une récente théorie de la mémoire a proposé que lorsqu'un souvenir déjà bien consolidé est réactivé, il redevient labile et susceptible aux modifications avant d'être restabilisé (reconsolidé) en mémoire à long terme. Ce nouveau modèle réfute le modèle classique de la consolidation qui propose qu'une fois consolidés, les souvenirs soient permanents et donc résistants aux effets des agents amnésiques. Les études validant la théorie de la reconsolidation abondent chez les animaux, mais encore peu d'études ont été réalisées chez les humains. L'objectif de cette thèse est de vérifier, dans une population de sujets sains et de sujets souffrant de trouble de stress post-traumatique (TSPT), l'efficacité d'un agent pharmacologique, le propranolol (un β-bloquant noradrénergique) à atténuer des souvenirs émotionnels nouvellement acquis ou déjà bien consolidés. Plus spécifiquement, nous avons mené un essai clinique contrôlé à double insu chez des sujets sains en leur administrant du propranolol (vs du placebo) lors de l'acquisition d'un nouveau souvenir et une semaine plus tard, lors de sa réactivation. L'objectif du premier article était d'évaluer l'efficacité du propranolol à diminuer la consolidation et la reconsolidation d'un souvenir émotionnel. Par ailleurs, puisque les études chez les animaux ont démontré que ces deux processus mnésiques s'effectuent à l'intérieur d'une fenêtre temporelle précise, le moment de l'administration du propranolol fut pris en considération. Les résultats ont démontré que le propranolol est en mesure de diminuer la consolidation et la reconsolidation d'une histoire émotionnelle tel que démontré par un pourcentage de bonnes réponses plus faible que le groupe contrôle lors des rappels. Toutefois, pour que cet effet soit observé, le propranolol doit être administré une heure avant la présentation des stimuli, pour la consolidation et une heure avant leur réactivation, pour la reconsolidation. En outre, les études portant sur la consolidation et la reconsolidation chez les animaux et chez les humains obtiennent parfois des résultats contradictoires. Ceci pourrait s'expliquer par le type de stimuli utilisé. Ainsi, l'objectif du second article était de préciser quel type d'information est le plus susceptible d'être affecté par le propranolol lors de son acquisition (consolidation) et lors de sa réactivation (reconsolidation). Pour ce faire, les éléments de l'histoire émotionnelle ont été divisés en fonction de leur valence (émotionnel ou neutre) et de leur centralité (central ou périphérique). Les résultats ont démontré le propranolol affecte l'ensemble des informations centrales lors du blocage de la consolidation, mais qu'il affecte plus spécifiquement les éléments émotionnels centraux lors de la reconsolidation. Notre groupe ayant précédemment démontré que le traitement avec le propranolol est en mesure de réduire les symptômes de TSPT chez une population clinique, nous nous sommes interrogés sur son efficacité à diminuer la mémoire implicite d'un événement traumatique. Le propranolol a été administré aux participants à 6 reprises (une fois par semaine sur une période de 6 semaines) lors de la réactivation de leur trauma. Les résultats ont révélé que le traitement avec le propranolol est en mesure de diminuer la réponse psychophysiologique des participants à l'écoute du compte rendu de leur trauma une semaine et 4 mois suivant la fin du traitement. En somme, cette thèse démontre que le propranolol est en mesure de bloquer la consolidation et la reconsolidation de souvenirs émotionnels chez l'humain lorsqu'il est administré une heure avant l'acquisition ou la réactivation des souvenirs. Il arrive en outre à atténuer un souvenir déclaratif émotionnel chez des sujets sains, mais également un souvenir implicite chez des sujets souffrant de TSPT. Ainsi, ces résultats ouvrent la voie à la création de nouveaux traitements pour les psychopathologies ayant comme étiologie un souvenir émotionnel intense.

ADAM: A Decentralized Parallel Computer Architecture Featuring Fast Thread and Data Migration and a Uniform Hardware Abstraction

The furious pace of Moore's Law is driving computer architecture into a realm where the the speed of light is the dominant factor in system latencies. The number of clock cycles to span a chip are increasing, while the number of bits that can be accessed within a clock cycle is decreasing. Hence, it is becoming more difficult to hide latency. One alternative solution is to reduce latency by migrating threads and data, but the overhead of existing implementations has previously made migration an unserviceable solution so far. I present an architecture, implementation, and mechanisms that reduces the overhead of migration to the point where migration is a viable supplement to other latency hiding mechanisms, such as multithreading. The architecture is abstract, and presents programmers with a simple, uniform fine-grained multithreaded parallel programming model with implicit memory management. In other words, the spatial nature and implementation details (such as the number of processors) of a parallel machine are entirely hidden from the programmer. Compiler writers are encouraged to devise programming languages for the machine that guide a programmer to express their ideas in terms of objects, since objects exhibit an inherent physical locality of data and code. The machine implementation can then leverage this locality to automatically distribute data and threads across the physical machine by using a set of high performance migration mechanisms. An implementation of this architecture could migrate a null thread in 66 cycles -- over a factor of 1000 improvement over previous work. Performance also scales well; the time required to move a typical thread is only 4 to 5 times that of a null thread. Data migration performance is similar, and scales linearly with data block size. Since the performance of the migration mechanism is on par with that of an L2 cache, the implementation simulated in my work has no data caches and relies instead on multithreading and the migration mechanism to hide and reduce access latencies.

Flavonoids and cognitive function: a review of human randomized controlled trial studies and recommendations for future studies

Evidence in support of the neuroprotective effects of flavonoids has increased significantly in recent years, although to date much of this evidence has emerged from animal rather than human studies. Nonetheless, with a view to making recommendations for future good practice, we review 15 existing human dietary intervention studies that have examined the effects of particular types of flavonoid on cognitive performance. The studies employed a total of 55 different cognitive tests covering a broad range of cognitive domains. Most studies incorporated at least one measure of executive function/working memory, with nine reporting significant improvements in performance as a function of flavonoid supplementation compared to a control group. However, some domains were overlooked completely (e.g. implicit memory, prospective memory), and for the most part there was little consistency in terms of the particular cognitive tests used making across study comparisons difficult. Furthermore, there was some confusion concerning what aspects of cognitive function particular tests were actually measuring. Overall, while initial results are encouraging, future studies need to pay careful attention when selecting cognitive measures, especially in terms of ensuring that tasks are actually sensitive enough to detect treatment effects.

Dissociating word stem completion and cued recall as a function of divided attention at retrieval

The aim of this study was to investigate the widely held, but largely untested, view that implicit memory (repetition priming) reflects an automatic form of retrieval. Specifically, in Experiment 1 we explored whether a secondary task (syllable monitoring), performed during retrieval, would disrupt performance on explicit (cued recall) and implicit (stem completion) memory tasks equally. Surprisingly, despite substantial memory and secondary costs to cued recall when performed with a syllable-monitoring task, the same manipulation had no effect on stem completion priming or on secondary task performance. In Experiment 2 we demonstrated that even when using a particularly demanding version of the stem completion task that incurred secondary task costs, the corresponding disruption to implicit memory performance was minimal. Collectively, the results are consistent with the view that implicit memory retrieval requires little or no processing capacity and is not seemingly susceptible to the effects of dividing attention at retrieval.

Understanding the relationship between repetition priming and mere exposure

Over the last two decades interest in implicit memory, most notably repetition priming, has grown considerably. During the same period, research has also focused on the mere exposure effect. Although the two areas have developed relatively independently, a number of studies has described the mere exposure effect as an example of implicit memory. Tacit in their comparisons is the assumption that the effect is more specifically a demonstration of repetition priming. Having noted that this assumption has attracted relatively little attention, this paper reviews current evidence and shows that it is by no means conclusive. Although some evidence is suggestive of a common underlying mechanism, even a modified repetition priming (perceptual fluency/attribution) framework cannot accommodate all of the differences between the two phenomena. Notwithstanding this, it seems likely that a version of this theoretical framework still offers the best hope of a comprehensive explanation for the mere exposure effect and its relationship to repetition priming. As such, the paper finishes by offering some initial guidance as to ways in which the perceptual fluency/attribution framework might be extended, as well as outlining important areas for future research.

Absolute versus relative difference measures of priming: Which is appropriate when baseline scores change with age?

It is often of theoretical interest to know if implicit memory (repetition priming) develops across childhood under a given circumstance. Methodologically, however, it is difficult to determine whether development is present when baseline performance for unstudied items improves with age. Calculation of priming in absolute (priming=studied - unstudied) or relative-to-baseline terms can lead to different conclusions. In first noting this problem, Parkin (1993) suggested using the Snodgrass (1989a) calculation of relative priming [priming=(studied - unstudied)/(maximum - unstudied)], and most developmental studies have since adopted this procedure. Here, we question the Snodgrass method because the Snodgrass method's results are not replicated in the picture identification task when baselines are equated experimentally across age groups. Instead, results support an absolute measure of priming. Theoretically, we argue against its core assumption; namely, that children and adults always lie on the same learning curve, with an equal maximum performance level and equal rate of learning.

The Role of Features and Context in Recognition of Novel Melodies

WE INVESTIGATED HOW WELL STRUCTURAL FEATURES such as note density or the relative number of changes in the melodic contour could predict success in implicit and explicit memory for unfamiliar melodies. We also analyzed which features are more likely to elicit increasingly confident judgments of "old" in a recognition memory task. An automated analysis program computed structural aspects of melodies, both independent of any context, and also with reference to the other melodies in the testset and the parent corpus of pop music. A few features predicted success in both memory tasks, which points to a shared memory component. However, motivic complexity compared to a large corpus of pop music had different effects on explicit and implicit memory. We also found that just a few features are associated with different rates of "old" judgments, whether the items were old or new. Rarer motives relative to the testset predicted hits and rarer motives relative to the corpus predicted false alarms. This data-driven analysis provides further support for both shared and separable mechanisms in implicit and explicit memory retrieval, as well as the role of distinctiveness in true and false judgments of familiarity.

Implizites Gedächtnis: unwillkürlich, entwicklungsresistent und altersunabhängig

Studied explicit memory and implicit memory performance in children, young adults, and old adults. Human Ss: 21 normal male and female Swiss preschool and school-age children (aged 4 yrs 8 mo to 6 yrs 5 mo) (Exp I). 14 normal male and female Swiss university students (Exp I). 21 normal male and female Swiss preschool and school-age children (aged 5 yrs 3 mo to 6 yrs 10 mo) (Exp II). 21 normal male and female Swiss university students (Exp II). 17 normal male and female Swiss old adults (aged 64–85 yrs) (participants in a course for senior citizens) (Exp III). 14 normal male and female Swiss old adults (aged 73–92 yrs) (nursing home residents) (Exp III). Ss participated in a simple learning task involving visual inspection or naming of pictures. Explicit memory was assessed via free recall and recognition of the stimulus material. Implicit memory was assessed with a perceptual identification task. Age differences in memory performance and in the influence of priming effects on memory performances were analyzed.

Synesthetic experiences enhance unconscious learning

Synesthesia is characterized by consistent extra perceptual experiences in response to normal sensory input. Recent studies provide evidence for a specific profile of enhanced memory performance in synesthesia, but focus exclusively on explicit memory paradigms for which the learned content is consciously accessible. In this study, for the first time, we demonstrate with an implicit memory paradigm that synesthetic experiences also enhance memory performance relating to unconscious knowledge.

Conscious recollection and the human hippocampal formation: evidence from positron emission tomography.

We used positron emission tomography (PET) to examine the role of the hippocampal formation in implicit and explicit memory. Human volunteers studied a list of familiar words, and then they either provided the first word that came to mind in response to three-letter cues (implicit memory) or tried to recall studied words in response to the same cues (explicit memory). There was no evidence of hippocampal activation in association with implicit memory. However, priming effects on the implicit memory test were associated with decreased activity in extrastriate visual cortex. On the explicit memory test, subjects recalled many target words in one condition and recalled few words in a second condition, despite trying to remember them. Comparisons between the two conditions showed that blood-flow increases in the hippocampal formation are specifically associated with the conscious recollection of studied words, whereas blood-flow increases in frontal regions are associated with efforts to retrieve target words. Our results help to clarify some puzzles concerning the role of the hippocampal formation in human memory.

Alcohol-related associative strength and drinking behaviours: concurrent and prospective relationships

The first part of this research assessed the longitudinal relationships between alcohol- related associative strength and alcohol use measured at two time- points, 6 months apart. Cross-lagged results support the utility of alcohol- related associative strength to predict drinking behaviours prospectively and vice versa. These results remained after competing explanations of previous use, autocorrelations between memory measures, sensation seeking and background variables of age and gender were accounted for. Findings offer further evidence for an implicit cognitions approach to drinking processes. In the second part of our study, cross-sectional analysis investigated potential mediating mechanisms in the relation of associative strength to quantity and frequency dimensions of drinking. Mediational models provide preliminary evidence that implicit memory processes may have differential effects on quantity and frequency dimensions of drinking behaviours. The results point to the possibility that increasing awareness of implicit alcohol-related associations may have utility in interventions for young adults.

Negative mood, implicit alcohol-related memory, and alcohol use in young adults: The moderating effect of alcohol expectancy

Objective Alcohol-related implicit (preconscious) cognitive processes are established and unique predictors of alcohol use, but most research in this area has focused on alcohol-related implicit cognition and anxiety. This study extends this work into the area of depressed mood by testing a cognitive model that combines traditional explicit (conscious and considered) beliefs, implicit alcohol-related memory associations (AMAs), and self-reported drinking behavior. Method Using a sample of 106 university students, depressed mood was manipulated using a musical mood induction procedure immediately prior to completion of implicit then explicit alcohol-related cognition measures. A bootstrapped two-group (weak/strong expectancies of negative affect and tension reduction) structural equation model was used to examine how mood changes and alcohol-related memory associations varied across groups. Results Expectancies of negative affect moderated the association of depressed mood and AMAs, but there was no such association for tension reduction expectancy. Conclusion Subtle mood changes may unconsciously trigger alcohol-related memories in vulnerable individuals. Results have implications for addressing subtle fluctuations in depressed mood among young adults at risk of alcohol problems.